Breast cancer is caused by the presence of cancer cells in the breast, which divide abnormally leading to abnormal growth (called in situ carcinoma) and the ability to invade normal tissue locally (invasive cancer). It is the most common cancer afflicting women, with a lifetime risk of 1 in 8. Breast cancer is more likely to develop in women over 50, but it can occur in younger women, too. When this happens, the cancer is typically more aggressive. In even rarer cases, men can develop breast cancer, too.
There are different types of breast cancer. These are subclassified according to whether the gandular or ductal units of the breast are involved. The majority of cases are ductal (70%).
In breast cancer, the primary tumour usually begins in the breast. However, once it becomes invasive, it may progress to the lymph nodes of the breast. Here, the cancer cells can metastasise (spread) by pentrating the lymphatic vessels, allowing them to circulate to other areas of the body.
On a more positive note, the survival rates of patients with breast cancer continue to improve with earlier diagnosis and treatment advancements.