Breast cancer is a cancer that starts in the cells of the breast Worldwide, breast cancer is the second most common type of cancer after lung cancer (10.4% of all cancer incidence, both sexes counted) and the fifth most common cause of cancer death. Worldwide, breast cancer is by far the most common cancer amongst women, with an incidence rate more than twice that of colorectal cancer and cervical cancer and about three times that of lung cancer. However breast cancer mortality worldwide is just 25% greater than that of lung cancer in women. In 2005, breast cancer caused 502,000 deaths worldwide (7% of cancer deaths; almost 1% of all deaths).The number of cases worldwide has significantly increased since the 1970s, a phenomenon partly blamed on modern lifestyles in the Western world.

In most cases, it isn't clear what causes normal breast cells to become cancerous. Doctors do know that only 5 percent to 10 percent of breast cancers are inherited. Families that do have genetic defects in one of two genes, breast cancer gene 1 (BRCA1) or breast cancer gene 2 (BRCA2), have a much greater risk of developing both breast and ovarian cancer. Other inherited mutations - including the ataxia-telangiectasia mutation gene, the cell-cycle checkpoint kinase 2 (CHEK-2) gene and the p53 tumor suppressor gene - also make it more likely that you'll develop breast cancer. If one of these genes is present in your family, you have a 50 percent chance of having the gene.

Inflammatory breast cancer is a type of breast cancer that involves the skin of the breast. This type of cancer comprises less than 4% of all breast cancers diagnosed each year in the US. The physical symptoms of inflammatory breast cancer include redness of the skin of the breast and a general swelling of the breast. In some cases, a lump may be present.

Types of Breast Cancer

Tumor grade: If the cancer is an invasive type, the pathologist assigns it a grade. The grade is based on how closely cells in the sample tissue resemble normal breast tissue under the microscope. The grading information, along with the cell type, helps your doctor determine treatment options.

Tubular carcinoma: This rare type of breast cancer gets its name from the appearance of the cancer cells under a microscope. Though it's an invasive breast cancer, the outlook is more favorable than it is for invasive ductal carcinoma or invasive lobular carcinoma.

Metaplastic carcinoma: Met plastic carcinoma represents less than 1 percent of all newly diagnosed breast cancers. This lesion tends to remain localized and contains several different types of cells that are not typically seen in other forms of breast cancer. Prognosis and treatment is the same as for invasive ductal carcinoma.

Lobular Carcinoma In Situ is NOT cancer. But it's a sign that the woman who has it is 6 to 7 more times likely to develop cancer, over the course of her lifetime, than a woman who doesn't have LCIS: the same risk you'd be at if your mother and sister both had cancer.

Most lumps turn out to be fibrocystic changes. The term "fibrocystic" refers to fibrosis and cysts. Fibrosis is the formation of fibrous (or scar-like) tissue, and cysts are fluid-filled sacs. Fibrocystic changes can cause breast swelling and pain. This often happens just before a period is about to begin. Your breasts may feel lumpy and, sometimes, you may notice a clear or slightly cloudy nipple discharge.