Breast Cancer Overview
Cancer is a group of diseases in which normal cells change and grow out of control. In breast cancer, the cancerous cells are usually cells of the lobules and ducts (ie, the glands that produce milk and the channels that carry milk to the nipple). Keep in mind that cancer, or carcinoma, of the breast can be broadly divided into two categories :
non-invasive or in situ carcinoma: cancer cells are confined to the areas where they originated, either the ducts (ductal carcinoma in situ; DCIS) or lobules (lobular carcinoma in situ; LCIS)
invasive carcinoma: cancers that started in ducts or lobules but have spread beyond them to invade surrounding tissues of the breast
To learn more about breast cancer click the links below.
Major Types and Pathology of Breast Cancer
Breast cancer is broadly divided into carcinoma in situ and invasive breast cancers. Carcinoma in situ, in turn, is categorized according to whether it is confined to the lobules or ducts :
Lobular carcinoma in situ (LCIS): Although LCIS probably does not develop into invasive cancer, women with LCIS have a higher risk of developing invasive cancer in either breast.
Ductal carcinoma in situ (DCIS): DCIS is the most common type of noninvasive breast cancer. If not treated, it may grow and become invasive cancer. DCIS can usually be cured with surgery and sometimes radiation. Invasive breast cancers are cancers that have spread beyond the ducts or lobules. Invasive cancers are categorized based on how they look under the microscope and how they compare to normal cells. This description, called the cancer grade, helps predict the patient’s outcome, or prognosis. Some major types of invasive breast cancer are summarized below
Types of Invasive Breast Cancer
Invasive ductal carcinoma (IDC)
Accounts for about 80% of invasive breast cancers
Begins in a duct of the breast, breaks through the duct wall and spreads into fatty tissue; cancer cells then spread into lymphatic channels or blood vessels and spread to other parts of the body
Invasive lobular carcinoma (ILC)
Accounts for 10% to 15% of invasive breast cancers
Begins in a lobule of the breast, breaks through lobe boundaries and, similar to IDC, spreads to other parts of the body
Contains a variety of cell types (eg, mixture of IDC and ILC); usually treated as if it were an invasive ductal cancer
Accounts for 5% of invasive breast cancers
A form of invasive ductal cancer with a defined boundary between the tumor cells and normal breast tissue; difficult to distinguish from normal IDC; most oncologists believe it should be treated as IDC
Very rare form of IDC; tumors include cells not normally found in the breast; treated similarly to IDC
Inflammatory breast cancer (IBC)
Accounts for 1% to 3% of all breast cancers
Form of cancer in which cancer cells have spread to lymph channels in the skin of the breast, giving the skin a red, swollen, orange-peel appearance; breast may also become larger, firmer, tender, or itchy; IBC has a greater chance of spreading and worse outlook than typical IDC or ILC
Rare type of IDC; also called mucinous carcinoma, formed from mucusproducing cancer cells; has a better outlook and lower chance of metastasis than IDC or ILC cancers of the same size
Accounts for about 2% of all invasive breast cancers
Form of IDC, but less likely to spread than ILC or IDC cancers of the same size
Apart from skin cancer, breast cancer is the most common cancer in women. In 2009, about 192,370 new cases of invasive breast cancer and 62,280 new cases of in situ breast cancer are expected to occur among U.S. women, for a total of about 254,650 new cases overall. The incidence of breast cancer and death rates generally increase with age. In fact, during 2000-2004, 95% of new cases of breast cancer, and 97% of deaths from breast cancer, occurred in women aged 40 and older. Age differences are also clearly seen in incidence rates: Women 20 to 24 years have the lowest rate of breast cancer (1.4 cases per 100,000), while women 75 to 79 years having the highest rate (465 cases per 100,000). White women have a higher incidence of breast cancer than African American women after age 40. However, African American women are more likely to die from breast cancer at every age. Women of other racial and ethnic groups have a lower incidence and death rates than white and African American women.
Other key facts and trends include :
In 2005, about 2.4 million women with a history of breast cancer were alive, most of whom were cancer-free
The incidence of breast cancer has decreased by 2.2% per year from 1999 to 2005. According to the American Cancer Society, this decline is probably due to an increase in mammography screening, as well as decreased used of hormone replacement therapy (HRT), following the publication of the results of the Women’s Health Initiative randomized trial in 2002.
The importance of early detection and diagnosis is seen in the fact that survival rates five years after diagnosis are markedly higher among women diagnosed at an earlier stage.
Like other diseases, risk factors for breast cancer can be divided into those that are modifiable (those that a person may change through behavioral modification) and non-modifiable (those that a person cannot normally change).
Below are a list of risk factors according to the American Cancer Society.
Non-modifiable Risk Factors include:
A major risk factor for developing breast cancer is simply being a woman. Men can develop breast cancer (approximately 1,910 cases of male breast cancer are expected in 2009), but the disease is about 100 times more common among women.
The risk of developing breast cancer increases as a woman ages. A woman’s overall lifetime risk of developing breast cancer is about 12% (1 in 8).
Genetic risk factors
About 5% to 10% of breast cancer cases are thought to be hereditary, resulting directly from gene changes (called mutations) inherited from a parent. There are several gene mutations that have been associated with an increased breast cancer risk.
BRCA1 and BRCA2:
In a person without this gene mutation, these genes act as tumor suppressors, producing proteins meant to prevent abnormal cell growth. When the gene is mutated, they are no longer able to function as tumor suppressors, so breast cancer is more likely to develop. Although mutations to these genes are relatively rare (less than 1% of the population), they can significantly increase risk if present. Women with an inherited BRCA1 or BRCA2 mutation have up to an 80% chance of developing breast cancer during their lifetime, and when they do it is often at a younger age than in women who are not born with one of these gene mutations. Women with these inherited mutations also have an increased risk for developing ovarian cancer.
Changes in other genes: Other gene changes might also lead to inherited breast cancers. These genes do not pass on the same level of breast cancer risk as the BRCA genes, and do not frequently cause familial or inherited breast cancer.
ATM: The ATM gene normally helps repair damaged DNA. Certain families with a high rate of breast cancer have been found to have mutations of this gene.
CHEK2: The CHEK2 gene increases breast cancer risk about two-fold when mutated. In women who carry the CHEK2 mutation and have a strong family history of breast cancer, the risk is greatly increased.
p53: Inherited mutations of the p53 tumor suppressor gene can also increase the risk of developing breast cancer, as well as several other cancers such as leukemia, brain tumors, and sarcomas (cancer of bones or connective tissue).
The Li-Fraumeni syndrome, named after the 2 researchers who first described this inherited cancer syndrome, is a rare cause of breast cancer. It develops if a person inherits only one functional copy of the p53 gene from their parents. Persons with this syndrome are at risk for a wide range of malignancies, with particularly high occurrences of breast cancer, brain tumors, acute leukemia, soft tissue sarcomas, bone sarcomas, and adrenal cortical carcinoma.
PTEN: The PTEN gene normally helps regulate cell growth. Inherited mutations in this gene cause Cowden syndrome, a rare disorder in which people are at increased risk for both benign and malignant breast tumors, as well as growths in the digestive tract, thyroid, uterus, and ovaries.
Genetic testing can be done to look for mutations in the BRCA1 and BRCA2 genes (or less commonly in other genes such as PTEN or p53).
Family history of breast cancer
Breast cancer risk is higher among women whose close blood relatives have this disease.
Having one first-degree relative (mother, sister, or daughter) with breast cancer approximately doubles a woman's risk. Having 2 first-degree relatives increases her risk about 5-fold.
Although the exact risk is not known, women with a family history of breast cancer in a father or brother also have an increased risk of breast cancer. Altogether, about 20% to 30% of women with breast cancer have a family member with this disease.
It’s important to note this means that 70% to 80% of women who get breast cancer DO NOT have a family history of this disease.
A woman with cancer in one breast has a 3- to 4-fold increased risk of developing
Personal history of breast cancerthe first cancer.a new cancer in the other breast or in another part of the same breast. This is different from a recurrence (return) of the first cancer.
Race and ethnicity
White women are slightly more likely to develop breast cancer than are African-American women. African-American women are more likely to die of this cancer. At least part of this seems to be because African-American women tend to have more aggressive tumors, although why this is the case is not known. Asian, Hispanic, and Native-American women have a lower risk of developing and dying from breast cancer.
Dense breast tissue
Breast density, a measure of glandular tissue, fatty tissue, is also a risk factor for breast cancer. Women with the highest levels of density have a 4- to 6-times increased risk of developing breast cancer. Dense breast tissue can also make it harder for doctors to spot problems on mammograms.
Certain benign breast conditions
Women diagnosed with certain benign breast conditions may have an increased risk of breast cancer. Some of these conditions are more closely linked to breast cancer risk than others. Doctors often divide benign breast conditions into 3 general groups, depending on how they affect this risk.
Non-proliferative lesions: These conditions are not associated with overgrowth of breast tissue). They do not seem to affect breast cancer risk, or if they do, it is to a very small extent. They include:
fibrocystic disease (fibrosis and/or cysts)
mild hyperplasia (an abnormal overgrowth of cells)
adenosis (non-sclerosing, or non-hardening of tissue)
phyllodes tumor (benign)
a single papilloma
other benign tumors (lipoma, hamartoma, hemangioma, neurofibroma)
Proliferative lesions without atypia: These show excessive growth of cells in the ducts or lobules of the breast tissue. They seem to raise a woman's risk of breast cancer slightly (1 1/2 to 2 times normal). They include:
usual ductal hyperplasia (without atypia)
several papillomas or papillomatosis
Proliferative lesions with atypia: In these conditions, there is excessive growth of cells in the ducts or lobules of the breast tissue, and the cells no longer appear normal. They have a stronger effect on breast cancer risk, raising it 4 to 5 times higher than normal. They include:
atypical ductal hyperplasia (ADH)
atypical lobular hyperplasia (ALH)
Women with a family history of breast cancer and either hyperplasia or atypical hyperplasia have an even higher risk of developing a breast cancer.
Women who have had more menstrual cycles because they started menstruating at an early age (before age 12) and/or went through menopause at a later age (after age 55) have a slightly higher risk of breast cancer. This may be related to a higher lifetime exposure to the hormones estrogen and progesterone.
Previous chest radiation
Women who, as children or young adults, had radiation therapy to the chest area as treatment for another cancer (such as Hodgkin disease or non-Hodgkin lymphoma) are at significantly increased risk for breast cancer. This varies with the patient's age when they had radiation. If chemotherapy was also given, the risk may be lowered if the chemotherapy stopped ovarian hormone production. The risk of developing breast cancer appears to be highest if the radiation was given during adolescence, when the breasts were still developing.
From the 1940s through the 1960s some pregnant women were given the drug diethylstilbestrol (DES) because it was thought to lower their chances of losing the baby (miscarriage). These women have a slightly increased risk of developing breast cancer. Women whose mothers took DES during pregnancy may also have a slightly higher risk of breast cancer.
Modifiable factors and breast cancer risk
Not having children, or having them later in life
Women who have had no children or who had their first child after age 30 have a slightly higher breast cancer risk. Having many pregnancies and becoming pregnant at an early age reduces breast cancer risk. Pregnancy reduces a woman's total number of lifetime menstrual cycles, which may be the reason for this effect.
Studies have found that women using oral contraceptives (birth control pills) have a slightly greater risk of breast cancer than women who have never used them, but this risk seems to decline once their use is stopped. Women who stopped using oral contraceptives more than 10 years ago do not appear to have any increased breast cancer risk. When thinking about using oral contraceptives, women should discuss their other risk factors for breast cancer with ther health care team.
Recent oral contraceptive use
Post-menopausal hormone therapy (PHT), also known as hormone replacement therapy (HRT), has been used for many years to help relieve symptoms of menopause and to help prevent osteoporosis (thinning of the bones). Earlier studies suggested it might have other health benefits as well, but more recent
Using post-menopausal hormone therapybetter designed studies have not found them.,
There are 2 main types of PHT. For women who still have a uterus (womb), doctors generally prescribe estrogen and progesterone (known as combined PHT). Because estrogen alone can increase the risk of cancer of the uterus, progesterone is added to help prevent this. For women who no longer have a uterus (those who've had a hysterectomy), estrogen alone can be prescribed. This is commonly known as estrogen replacement therapy (ERT).
Combined PHT: Long-term use (several years or more) of combined post-menopausal hormone therapy increases the risk of breast cancer and may also increase the chances of dying of breast cancer. Large studies have found that there is an increased risk of breast cancer related to the use of combined PHT. Combined PHT also increases the likelihood that the cancer may be found at a more advanced stage, possibly because it reduces the effectiveness of mammograms.
The increased risk from combined PHT appears to apply only to current and recent users. A woman's breast cancer risk seems to return to that of the general population within 5 years of stopping combined PHT.
ERT: The use of estrogen alone does not appear to increase the risk of developing breast cancer significantly, if at all. But when used long term (for more than 10 years), ERT has been found to increase the risk of ovarian and breast cancer in some studies.
At this time there appear to be few strong reasons to use post-menopausal hormone therapy (combined PHT or ERT), other than possibly for the short-term relief of menopausal symptoms. Along with the increased risk of breast cancer, combined PHT also appears to increase the risk of heart disease, blood clots, and strokes. It does lower the risk of colorectal cancer and osteoporosis, but this must be weighed against the possible harm, and it should be noted that there are other effective ways to prevent osteoporosis. Although ERT does not seem to have much effect on breast cancer risk, it does increase the risk of stroke.
The decision to use PHT should be made by a woman and her doctor after weighing the possible risks and benefits (including the severity of her menopausal symptoms), and considering her other risk factors for heart disease, breast cancer, and osteoporosis. If a woman and her doctor decide to try PHT for symptoms of menopause, it is usually best to use it at the lowest dose that works for her and for as short a time as possible.
Some studies suggest that breast-feeding may slightly lower breast cancer risk, especially if breast-feeding is continued for 1 1/2 to 2 years. But this has been a difficult area to study, especially in countries such as the United States, where breast-feeding for this long is uncommon.
The explanation for this possible effect may be that breast-feeding reduces a woman's total number of lifetime menstrual cycles (similar to starting menstrual periods at a later age or going through early menopause).
Use of alcohol is clearly linked to an increased risk of developing breast cancer. The risk increases with the amount of alcohol consumed. Compared with non-drinkers, women who consume 1 alcoholic drink a day have a very small increase in risk. Those who have 2 to 5 drinks daily have about 1 1/2 times the risk of women who drink no alcohol. Excessive alcohol use is also known to increase the risk of developing cancers of the mouth, throat, esophagus, and liver. The American Cancer Society recommends that women limit their consumption of alcohol to no more than one drink per day.
Being overweight or obese
Being overweight or obese has been found to increase breast cancer risk, especially for women after menopause. Before menopause your ovaries produce most of your estrogen, and fat tissue produces a small amount of estrogen. After menopause (when the ovaries stop making estrogen), most of a woman's estrogen comes from fat tissue. Having more fat tissue after menopause can increase your estrogen levels and thereby increase your likelihood of developing breast cancer.
The connection between weight and breast cancer risk is complex, however. For example, the risk appears to be increased for women who gained weight as an adult but may not be increased among those who have been overweight since childhood. Also, excess fat in the waist area may affect risk more than the same amount of fat in the hips and thighs. Researchers believe that fat cells in various parts of the body have subtle differences that may explain this.
The American Cancer Society recommends you maintain a healthy weight throughout your life by balancing your food intake with physical activity and avoiding excessive weight gain.
Lack of physical activity
Evidence is growing that physical activity in the form of exercise reduces breast cancer risk. The only question is how much exercise do you need? In one study from the Women's Health Initiative (WHI) as little as 1.25 to 2.5 hours per week of brisk walking reduced a woman's risk by 18%. Walking 10 hours a week reduced the risk a little more.
To reduce your risk of breast cancer, the American Cancer Society recommends 45 to 60 minutes of intentional physical activity 5 or more days a week.
Factors with uncertain, controversial, or unproven effect on breast cancer risk
Studies of fat in the diet have not clearly shown that this is a breast cancer risk factor.
Most studies have found that breast cancer is less common in countries where the typical diet is low in total fat, low in polyunsaturated fat, and low in saturated fat. On the other hand, many studies of women in the United States have not related breast cancer risk to dietary fat intake. Researchers are still not sure how to explain this apparent disagreement. Studies comparing diet and breast cancer risk in different countries are complicated by other differences (such as activity level, intake of other nutrients, and genetic factors) that might also alter breast cancer risk.
More research is needed to better understand the effect of the types of fat eaten on breast cancer risk. But it is clear that calories do count, and fat is a major source of these. High-fat diets can lead to being overweight or obese, which is a breast cancer risk factor. A diet high in fat has also been shown to influence the risk of developing several other types of cancer, and intake of certain types of fat is clearly related to heart disease risk.
The American Cancer Society recommends eating a healthy diet with an emphasis on plant sources. This includes eating 5 or more servings of vegetables and fruits each day, choosing whole grains over processed (refined) grains, and limiting consumption of processed and red meats.
Internet e-mail rumors have suggested that chemicals in underarm antiperspirants are absorbed through the skin, interfere with lymph circulation, cause toxins to build up in the breast, and eventually lead to breast cancer. There is very little laboratory or population-based evidence to support this rumor.
One small study has found trace levels of parabens (used as preservatives in antiperspirants and other products), which have weak estrogen-like properties, in a small sample of breast cancer tumors. However, the study did not look at whether parabens caused the tumors. This was a preliminary finding, and more research is needed to determine what effect, if any, parabens may have on breast cancer risk. On the other hand, a large study of breast cancer causes found no increase in breast cancer in women who used underarm antiperspirants or shaved their underarms.
Internet e-mail rumors and at least one book have suggested that bras cause breast cancer by obstructing lymph flow. There is no good scientific or clinical basis for this claim. Women who do not wear bras regularly are more likely to be thinner, which would likely contribute to any perceived difference in risk.
Several studies have provided very strong data that neither induced abortions nor spontaneous abortions (miscarriages) have an overall effect on the risk of breast cancer. For more detailed information, see the separate American Cancer Society document, Can Having an Abortion Cause or Contribute to Breast Cancer?
Several studies have found that breast implants do not increase breast cancer risk, although silicone breast implants can cause scar tissue to form in the breast. Implants make it harder to see breast tissue on standard mammograms, but additional x-ray pictures called implant displacement views can be used to examine the breast tissue more completely.
Chemicals in the environment
A great deal of research has been reported and more is being done to understand possible environmental influences on breast cancer risk.
Of special interest are compounds in the environment that have been found in lab studies to have estrogen-like properties, which could in theory affect breast cancer risk. For example, substances found in some plastics, certain cosmetics and personal care products, pesticides (such as DDE), and PCBs (polychlorinated biphenyls) seem to have such properties.
While this issue understandably invokes a great deal of public concern, at this time research does not show a clear link between breast cancer risk and exposure to these substances. Unfortunately, studying such effects in humans is difficult. More research is needed to better define the possible health effects of these and similar substances.
Most studies have found no link between cigarette smoking and breast cancer. Although some studies have suggested smoking increases the risk of breast cancer, this remains controversial.
An active focus of research is whether secondhand smoke increases the risk of breast cancer. Both mainstream and secondhand smoke contain chemicals that, in high concentrations, cause breast cancer in rodents. Chemicals in tobacco smoke reach breast tissue and are found in breast milk.
The evidence on secondhand smoke and breast cancer risk in human studies is controversial, at least in part because smokers have not been shown to be at increased risk. One possible explanation for this is that tobacco smoke may have different effects on breast cancer risk in smokers and in those who are just exposed to smoke.
A report from the California Environmental Protection Agency in 2005 concluded that the evidence about secondhand smoke and breast cancer is "consistent with a causal association" in younger, mainly pre-menopausal women. The 2006 US Surgeon General's report, The Health Consequences of Involuntary Exposure to Tobacco Smoke, concluded that there is "suggestive but not sufficient" evidence of a link at this point. In any case, this possible link to breast cancer is yet another reason to avoid secondhand smoke.
Several studies have suggested that women who work at night — for example, nurses on a night shift — may have an increased risk of developing breast cancer. This is a fairly recent finding, and more studies are looking at this issue. Some researchers think the effect may be due to changes in levels of melatonin, a hormone whose production is affected by the body's exposure to light, but other hormones are also being studied.
Most women experience no symptoms in the earliest stages of breast cancer. Since this is when the tumor is small and most treatable, regular breast exams — ie, mammography screening and clinical breast exams (CBE)— are important for detecting disease before symptoms begin.
In later stages, the most common sign of breast cancer is a painless mass or lump that may be hard or have uneven edges.
Other less common signs and symptoms may include:
breast pain or heaviness
persistent breast changes (such as thickening, swelling, redness, and discharge from the nipples)
Symptoms of advanced breast cancer may include:
swelling of the arm next to the breast
Diagnosis of breast cancer
Most breast cancers are first discovered as a lump by the patient or during a routine physical examination or mammography. In the first step of diagnosis, the physician will conduct a variety of tests to determine whether the abnormality is benign or malignant (cancerous). If the lesion is found to be cancerous, various follow-up tests are conducted to determine the type of cancer, its location, and the best treatment approaches. The major initial tests involved in diagnosing breast cancer are summarized below.
Physical examination: The physician will take a medical history to learn more about the patient’s past history or family history of breast cancer. The physician will also conduct a general physical examination and an examination of the breasts, called palpation, to look for abnormalities in breast texture and size, skin, nipples, presence of lumps or masses, and lymph node abnormalities.
Imaging: Three major noninvasive imaging tests may be used in diagnosing breast cancer. Mammography — which uses low levels of x-rays to produce images that can identify lumps or masses in the breast and their size — is the gold standard in screening for breast cancer. A breast ultrasound uses high frequency sound waves to produce images and may help identify whether a breast abnormality is a benign fluid filled cyst or potentially cancerous solid tissue. And magnetic resonance imaging (MRI) uses magnetic fields and radio frequency waves to produce highly detailed images of breast tissue; MRI can detect lesions missed by mammography, ultrasound, and physical examinations, and can help define the size and extent of an abnormality.
Biopsy: A biopsy is an invasive, interventional procedure in which a tissue sample is obtained and examined under the microscope for cancerous cells. Biopsies can be done with a needle or by scalpel if a larger sample is needed.
As noted above, if the biopsy and other tests confirm breast cancer, the physician will order other tests to better determine the typeof cancer, how far it has spread, and thus the best approach to treatment. These tests include:
Chest x-ray: In women with invasive breast cancer, chest x-rays may be given before surgery to see if the cancer has spread to the lungs.
Bone scan: A bone scan may be performed to see if the breast cancer has spread to the bone.
Computerized tomography: Computerized tomography (CT) scans are usually performed in women with later stages of breast cancer to determine if the cancer has spread to other organs.
Positron emission tomography: Positron emission tomography (PET) scans can detect cancer based on the higher rate of metabolism in cancer cells compared with normal cells. Some newer devices combine PET scans with CT scans.
Blood tests: Physicians may conduct various blood tests to plan for surgery and treatment, as well as to determine whether the cancer has spread. These tests include the complete blood count (assesses blood for the proper type and number of blood cells) and various blood chemical and enzyme tests.
Tumor tests: As noted earlier, tumor cells that express estrogen or progesterone receptors on their surface may be stimulated by the presence of estrogen and progesterone. Thus, the hormone receptor assay tests cancer cells for the presence of these receptors. In addition, breast cancer cells may be tested for increased levels of HER-2/neu, the protein that promotes tumor growth.
Cancer grading: When pathologists examine breast cancer cells under a microscope, they assign a tumor grade based on how they compare to normal breast tissue. The more the cancer cells resemble normal cells, the lower the grade and the less likely they are to grow. Low grade tumors (eg, Grade 1) may be referred to as “well-differentiated” (more closely resembles normal breast cells), while higher tumors (eg, Grade 3) may be called “poorly differentiated”, meaning that the cells have lost their resemblance to normal cells.
Breast cancer treatment can be divided into two broad categories:
Treatment of the breast: Consists of three major approaches: surgery of the breast (primarily), lymph node surgery, and radiation therapy
Treatment of cancer cells that have spread: Treatment of cancer cells that have spread beyond the breast and lymph nodes of the armpit usually involves systemic therapy (eg, chemotherapy and hormone therapy)
Treatment of the breast
Surgical treatment. In most cases, cancer within the breast is treated with one of two types of surgery: breast-conserving surgery and mastectomy. Breast conservation surgery includes a lumpectomy, in which only the breast lump and a rim of normal surrounding breast tissue is removed, plus radiation therapy. In other variations, up to one-fourth of the breast may be removed. Breast conservation therapy is as effective as a mastectomy for most women with stage I or II breast cancer, and its main advantage is cosmetic. However, it is not an option for all women, such as those with prior radiation therapy of the affected breast or those with widespread suspicious or malignant-appearing abnormalities in the breast.
In a mastectomy, the entire breast and nipple is surgically removed. Two major types of mastectomy are the total mastectomy, in which the entire breast — but no lymph nodes or underlying muscle — is removed, and the modified radical mastectomy. In a modified radical mastectomy, in addition to the entire breast, some axillary (under arm) lymph nodes are removed.
Lymph node surgery. Regardless of the type of breast surgery a woman receives, in most cases some or all of their axillary lymph nodes are also surgically removed for examination under a microscope to see if cancerous cells are present. This is important because cancer that has spread to the lymph nodes is more likely to have also entered the blood stream and traveled to other parts of the body. In an axillary lymph node dissection, all of the axillary lymph nodes are removed, while in a sentinel lymph node biopsy, only a few sentinel lymph nodes are removed. (Note: a sentinel lymph node is the first lymph node to which cancer is likely to spread from the primary tumor.)
Radiation therapy. In radiation therapy, high-energy rays (or particles) are beamed at the breast after surgery, or in some cases after a mastectomy, to kill any remaining cancer cells in the breast, chest wall, or lymph nodes. Radiation therapy may be given in several ways, including:
External beam radiation: delivered by a machine outside the body after a lumpectomy. Treatments are usually given 5 days a week for 6 to 7 weeks.
Brachytherapy: delivered by means of radioactive materials placed in or near the location of the tumor; brachytherapy may be given in addition to external beam radiation therapy.
Treatment of cancer that has spread
Physicians treat cancer cells that have spread beyond the breast with systemic therapy. Systemic therapy refers to treatments that travel through the entire body, rather than being localized to the cancerous tissue. Systemic therapy can be used as either adjuvant therapy (used with a primary therapy to increase its effectiveness) or neoadjuvant therapy (used before surgery to shrink a tumor and make surgery easier). Three major types of systemic therapy for breast cancer are chemotherapy, hormonal therapy, and monoclonal antibody therapy:
Chemotherapy: Chemotherapy refers to a variety of drugs that are usually given intravenously or by mouth and that kill the cancer cells. Note that many of these drugs are used individually and/or in specific combinations and regimens depending on the patient and clinical situation. For example, a particular regimen may be based on whether the cancer is recurrent, metastatic, or the tumor is HER-2/neu positive. Many other factors are considered in selecting and dosing chemotherapy treatments for breast cancer, including the duration of treatment cycles and recovery periods and side effects.
Hormonal therapy: Hormonal treatments act by either blocking the effects of estrogen or by lowering estrogen levels. Treatments that block the effects of estrogen include anti-estrogen drugs such as tamoxifen, toremifene, and fulvestrant. Therapies that lower estrogen levels include aromatase inhibitors, which block an enzyme that makes estrogen in postmenopausal women. In addition, certain types of surgery, radiation and drugs can lower estrogen levels by stopping the ovaries from producing estrogen.
Monoclonal antibody therapy: Monoclonal antibody treatments for breast cancer include trastuzumab (Herceptin), which acts against the HER-2/neu receptor on cancer cells that express this receptor. Trastuzumab may be used as adjuvant therapy to reduce the risk of recurrence or as neoadjuvant therapy. Another monoclonal antibody, bevacizumab (Avastin), prevents the growth of new blood vessels that supply tumor cells, and may be used in patients with metastatic breast cancer in combination with paclitaxel.
The importance of screening
Because breast cancer is more easily treated (and often curable) when found early, the American Cancer Society (ACS) provides screening guidelines for early detection. In general, women 20 to 39 years old should have a clinical breast exam (CBE) every three years, and those 40 years and older should have a CBE and mammogram every year. The ACS also suggests monthly breast self-exams (BSE) as an option for women over age 20.
MRI and patients at increased risk
In 2007, an expert panel of the American Cancer Society recommended that women with a high lifetime risk of breast cancer (20% to 25% or greater) receive MRI screening every year, in addition to annual mammography.
The panel also recommended that women with a moderately increased risk (15%-20% lifetime risk) talk with their doctors about the benefits and limitations of adding MRI screening to their yearly mammogram.