Together, the lymph vessels and lymph nodes make up the lymphatic system, which circulates a fluid called lymph throughout the body. Lymph contains cells that help fight infection and disease. When breast cancer spreads outside the breast, cancer cells are most often found under the arm in the lymph nodes. In many cases, if the cancer has reached the lymph nodes, cancer cells may have also spread to other parts of the body via the lymphatic system or through the bloodstream. Significance of breast cancer Breast cancer is second only to lung cancer as the leading cause of cancer death among women in the United States.
Breast cancer occurs in men also, but the number of new cases is small.
Early detection and effective treatment is expected to reduce the number of women who die from breast cancer, and development of new methods of prevention continue to be studied. Breast cancer prevention Breast cancer can sometimes be associated with known risk factors for the disease. Many risk factors are modifiable though not all can be avoided. Tamoxifen for Prevention of Breast Cancer Tamoxifen is a drug that blocks the effect of estrogen on breast cancer cells. A large study has shown that tamoxifen lowers the risk of getting breast cancer in women who are at elevated risk of getting breast cancer.