Doctor's Notes on Breast Cancer
Breast cancer occurs when the cells of the breast start to grow abnormally. Breast cancer occurs in both men and women. The breasts are made of fat, glands, and connective (fibrous) tissue. The breast has several lobes, which split into lobules that end in the milk glands. Tiny ducts run from the many tiny glands, connect together, and end in the nipple. Ductal cancer that arises in the ducts accounts for 80% of breast cancers. Lobular cancer develops in the lobules and accounts for approximately 10%-15% of breast cancers.
Early stage breast cancer usually doesn’t cause any symptoms though sometimes it’s possible to feel a lump in the breast. Pain is uncommon. Breast cancer may be discovered before symptoms appear by finding an abnormality on mammography or feeling a breast lump. Other symptoms of breast cancer may include breast discharge, nipple inversion, or changes in the skin overlying the breast (including redness, changes in texture, and puckering).
Breast Cancer Symptoms
Early stage breast cancer usually has no symptoms or signs, although sometimes it's possible to feel a lump in the breast. It is usually not painful.
Most people discover breast cancer before symptoms appear, either by finding an abnormality on mammography or feeling a breast lump. A lump in the armpit or above the collarbone that does not go away may be a sign of cancer. Other possible symptoms are breast discharge, nipple inversion, or changes in the skin overlying the breast.
- Most breast lumps are not cancerous. A doctor should evaluate all breast lumps.
- Breast discharge is a common problem. Discharge is most concerning if it is from only one breast or if it is bloody. In any case, a doctor should evaluate all breast discharge.
- Nipple inversion is a common variant of normal nipples, but nipple inversion that is a new development needs to be of concern.
- Changes in the skin of the breast include redness, changes in texture, and puckering. Skin diseases usually cause these changes but occasionally can be associated with breast cancer.
Signs and symptoms of HER2-positive breast cancer are the same as those of all breast cancers. It is not possible to determine HER2 presence by the clinical signs and symptoms.
Breast Cancer Causes
Many women who develop breast cancer have no risk factors other than age and gender.
- Gender is the biggest risk because breast cancer occurs mostly in women.
- Age is another critical breast cancer risk factor. Breast cancer may occur at any age, though the risk of breast cancer increases with age. The average woman at 30 years of age has one chance in 280 of developing breast cancer in the next 10 years. This chance increases to one in 70 for a woman 40 years of age, and to one in 40 at 50 years of age. A 60-year-old woman has a one in 30 chance of developing breast cancer in the next 10 years.
- White women are slightly more likely to develop breast cancer than African-American women in the U.S.
- A woman with a personal history of cancer in one breast has a three- to fourfold greater risk of developing a new cancer in the other breast or in another part of the same breast. This refers to the risk for developing a new tumor and not a recurrence (return) of the first cancer.
Genetic Causes of Breast Cancer
Family history is a risk factor for breast cancer. Both maternal and paternal relatives are important. The risk is highest if the affected relative developed breast cancer at a young age, had cancer in both breasts, or if she is a close relative. First-degree relatives (mother, sister, and daughter) are most important in estimating risk. Several second-degree relatives (grandmother, aunt) with breast cancer may also increase risk. Breast cancer in a male increases the risk for all his close female relatives. Having relatives with both breast and ovarian cancer also increases a woman's risk of developing breast cancer.
There is great interest in genes linked to breast cancer. About 5%-10% of breast cancers are believed to be hereditary, because of mutations, or changes, in certain genes that are passed along in families.
- BRCA1 and BRCA2 are abnormal genes that, when inherited, markedly increase the risk of breast cancer to a lifetime risk estimated between 45%-65%. Women with these abnormal genes also have an increased likelihood of developing ovarian cancer. Women who have the BRCA1 gene tend to develop breast cancer at an early age.
- BRCA2 mutations are associated with a lifetime male breast cancer risk of about 6.8%.
- Testing for these genes is expensive and is not always covered by insurance.
- The issues around testing are complicated, and women who are interested in testing should discuss their risk factors with their health care providers and may want to talk to a genetic counselor.
Hormonal Causes of Breast Cancer
Hormonal influences play a role in the development of breast cancer.
- Women who have early onset of menstruation (early menarche -- 12 or younger) or experience a late menopause (55 or older) have a slightly higher risk of developing breast cancer. Conversely, being older at the time of the first menstrual period and early menopause tend to protect one from breast cancer.
- Having a child before 30 years of age may provide some protection, and having no children may increase the risk for developing breast cancer.
- Using oral contraceptive pills means that a woman has a slightly increased risk of breast cancer than women who have never used them. This risk appears to decrease and return to normal with time once a woman stops taking the pills.
- A large study conducted by the Women's Health Initiative showed an increased risk of breast cancer in postmenopausal women who were on a combination of estrogen and progesterone for several years. Therefore, women who are considering hormone therapy for menopausal symptoms need to discuss the risk versus the benefit with their health care providers. Patients should weigh quality of life concerns against the relative risks of such medications.
Lifestyle and Dietary Causes of Breast Cancer
Breast cancer seems to occur more frequently in countries with high dietary intake of fat, and being overweight or obese is a known risk factor for breast cancer, particularly in postmenopausal women.
- This link is thought to be an environmental influence rather than genetic. For example, Japanese women, at low risk for breast cancer while in Japan, increase their risk of developing breast cancer after coming to the United States.
- Several studies comparing groups of women with high- and low-fat diets, however, have failed to show a difference in breast cancer rates.
Alcohol consumption is also an established risk factor for the development of breast cancer. The risk increases with the amount of alcohol consumed. Women who consume two to five alcoholic beverages per day have a risk about one and a half times that of nondrinkers for the development of breast cancer. Consumption of one alcoholic drink per day results in a slightly elevated risk.
Studies are also showing that regular exercise may reduce a woman's risk of developing breast cancer. Studies have not definitively established how much activity provides a significant reduction in risk. One study from the Women's Health Initiative (WHI) showed that as little as one and a quarter to two and a half hours per week of brisk walking reduced a woman's breast cancer risk by 18%.
Benign Breast Disease
- Fibrocystic breast changes are very common. Fibrocystic breasts are lumpy with some thickened tissue and are frequently associated with breast discomfort, especially right before the menstrual period. This condition does not lead to breast cancer.
- However, certain other types of benign breast changes, such as those diagnosed on biopsy as proliferative or hyperplastic, do predispose women to the later development of breast cancer.
Environmental Causes of Breast Cancer
Radiation treatment increases the likelihood of developing breast cancer but only after a long delay. For example, women who received radiation therapy to the upper body for treatment of Hodgkin's disease before 30 years of age have a significantly higher rate of breast cancer than the general population.
The outlook for women with breast cancer is improving constantly. Due to increased awareness, opportunities for early detection, and treatment advances, survival rates continue to climb. In the U.S., October is Breast Cancer Awareness Month and the campaign is designed to increase breast cancer awareness. There are many organizations that support Breast Cancer Awareness Month and provide assistance within early detection plans. Organizations also put together breast cancer fundraisers such as walks and events that support breast cancer research and help fund patients with socio-economic disadvantages.
Breast Cancer : Symptoms & Signs QuizQuestion
A lump in the breast is almost always cancer.See Answer
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.