Breast Cancer Basics

Breast cancer can be managed, and even cured, if caught early and before it spreads. Your vigilance in preventing the disease should start at a young age because it can develop early, even in women with no family history. Learn about breast cancer, risk factors, and effective prevention to increase your chances of avoiding breast cancer altogether.

Feel free to contact us with suggestions for additional topics. In addition, please refer to our Breast Cancer Blog for recent developments in breast cancer risk assessment, research, and treatment.

What is Breast Cancer?

Breast cancer is a malignant (cancerous) tumor that starts with cells of the breast. While the disease is found most commonly in women, men can also get breast cancer. Breast cancer is the most common cancer among women in the United States, other than skin cancer. It’s the second leading cause of cancer death in women, after lung cancer.

How Many Women Will Get Breast Cancer

1 in 8 women will develop breast cancer over the course of their lifetimes. In 2010, 207,090 new cases of invasive breast cancer were diagnosed in women and about 39,840 women passed away as a result of the disease. In the same year, about 54,010 new cases of carcinoma in situ (CIS) were diagnosed (CIS is the earliest form of non-invasive breast cancer). Breast cancer death rates have been decreasing, most likely the result of better risk assessment and early detection. The increased frequency of genetic testing, self breast exams, mammograms, and breast scans has allowed many women to detect breast cancer at an early stage, prior to metastases.

What Causes Breast Cancer

Breast cancer results when certain changes in DNA cause normal breast cells to become cancerous. DNA is the chemical in each of our cells that makes up our genes, the instructions for how our cells work. Some inherited DNA mutations can increase the risk for developing cancer. For instance, BRCA1 and BRCA2 are tumor suppressor genes that keep cancer tumors from forming. When they mutate, cells are less likely to die at the proper time, and cancer is more likely to develop.

While we do not yet know exactly what causes breast cancer, we know that certain risk factors are linked to the disease. Having a risk factor, or even several, doesn’t mean that a woman will certainly develop breast cancer. Some women who have one or more risk factors never get the disease.

Cancer Stages

Staging is the process of determining the breadth of the cancer at the time it’s found. Cancer stage is the most important factor in choosing a treatment option. The stage is based on whether the cancer is invasive or non-invasive, the size of the tumor, how many lymph nodes are affected, and whether the cancer has spread to other parts of the body.

The most common system used to describe the stages of breast cancer is the AJCC/TNM system. This system takes into account the tumor size and spread (T), whether the cancer has spread to lymph nodes (N), and whether it has spread to distant organs (M, a.k.a. metastasis). Numbers following the T, N, and M give details about the particular cancer.

All of the information is combined in a process called stage grouping. The stage is then expressed as a Roman numeral. After stage 0 (CIS), stages include I through IV (1-4). Some of the stages are further sub-divided using the letters A, B, and C. As a rule, the lower the number, the less the cancer has spread. A higher number, such as stage IV (4), indicates a more advanced cancer. Cancers with similar stages tend to have a similar outlook and are often treated in a similar way. After looking at the test results, your doctor will communicate the stage of the cancer. Breast cancer staging can be complex. Be sure to ask your doctor to explain the determined stage.

Survival Rates for Breast Cancer

The 5-year survival rate refers to the percentage of patients who live at least five years after their cancer diagnosis. Of course, many people live much longer than five years. Patients with cancer can also die from other causes, for which these numbers do not take into account. These percentages are based on women treated a number of years ago. Because doctors now find more cancers earlier and use newer, better treatments, the survival rates are getting better all the time.

 Stage  5-Year Survival Rate
 0 93%
 1 88%
 IIA 81%
 IIB 74%
 IIIA 67%
 IIIB 41%
 IIIC 49%
 IV 15%

Note: Figures found in the National Cancer Data Base. Subjects were diagnosed with breast cancer in 2001 and 2002. The data for IIIB and IIIC is correct as written.