Breast Cancer

Home » Breast Cancer » Overview, Incidence and Prevalence, Types, Risk Factors

Questions to Ask Your Doctor About Your Cancer
(Free Handout)

Overview

Breast cancer is malignant abnormal cell growth in the breast. Cancer cells may spread to other areas of the body (called metastasis). Fibrocystic changes (e.g., formation of cysts, scar tissue) may cause benign (i.e., noncancerous) lumps in the breast. It is important for women to become familiar with their breasts and report changes (e.g., lump, nipple discharge, asymmetry) to their health care practitioner.

Incidence and Prevalence
In women, breast cancer is the second most common type of cancer and the second leading cause of cancer-related deaths. One in eight women in the United States will develop breast cancer during her lifetime.

According to the American Cancer Society (ACS), approximately 200,000 new cases of breast cancer are diagnosed each year in the United States, and the disease causes about 41,000 deaths annually.

The incidence of breast cancer rises after age 40. The highest incidence (approximately 80% of invasive cases) occurs in women over age 50.

Types of Breast Cancer

Most breast cancer develops in glandular tissue and is classified as adenocarcinoma. The earliest form of the disease, ductal carcinoma in situ (DCIS), develops solely in the milk ducts. The most common type of breast cancer, invasive ductal carcinoma (IDC), develops from DCIS, spreads through the duct walls, and invades the breast tissue. Invasive ductal carcinoma also is called infiltrating ductal carcinoma.

Invasive lobular carcinoma originates in the milk glands and accounts for 10–15% of invasive breast cancers. Less common types of breast cancer include the following:

• Inflammatory (breast tissue is warm and appears red; tends to spread quickly)
• Medullary carcinoma (originates in central breast tissue)
• Mucinous carcinoma (invasive; usually occurs in postmenopausal women)
• Paget's disease of the nipple (originates in the milk ducts and spreads to the skin of the nipples or areola)
• Phyllodes tumor (tumor with a leaf-like appearance that extends into the ducts; rarely metastasizes)
• Tubular carcinoma (small tumor that is often undetectable by palpation)

Rarely, sarcomas (cancer of the connective tissue) and lymphomas (cancer of the lymph tissue) develop in the breasts.

Risk Factors

Most women who develop breast cancer have no identifiable risk factors other than their gender. The condition is 100 times more common in women. The growth of breast cancer tumors is often affected by the presence of estrogen and progesterone. The following risk factors result from exposure to these hormones:

• Age (over age 50)
• First pregnancy after age 30
• Long-term synthetic hormone replacement therapy (HRT)
• Menstruation before age 12
• Menopause after age 50
• Nulliparity (never gave birth)

Other risk factors include the following:

• Alcohol use (Women who have 2 to 5 drinks daily have about 1.5 times the risk of women who do not consume alcohol.)
• Family history of the disease (mother or sister with premenopausal breast cancer)
• Genetic link
• History of breast biopsy or radiation to the chest
• Obesity
• Personal history of the disease—women with a history of breast cancer are 3 to 4 times more likely to have a recurrence
• Race (slightly more common in Caucasians)
• Sedentary lifestyle

Recent studies have shown that breast cancer may be more aggressive (i.e., more likely to spread or recur) in women who are overweight or obese.

Approximately 5% of breast cancer cases have a genetic link that results from an inherited mutation in genes identified as BRCA1 and BRCA2. Patients who inherit an altered BRCA1 or BRCA2 gene have an increased risk for developing premenopausal breast cancer and are more likely to have family members with the condition. Patients concerned about the genetic risk for breast cancer should speak to their health care practitioner about genetic testing.

Cause

The cause of breast cancer is unknown.

Breast Cancer Resources

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