Breast Cancer

Breast cancer starts when genes responsible for normal and orderly cell growth mutate and begin rampant reproduction. This uncontrolled growth forms a breast tumor which may eventually be felt and which can spread (metastasize) to other parts of the body.

Only 5 to 10 percent of breast cancers are caused by mutated genes that are inherited. The vast majority of breast cancers are caused by the “wear and tear” of the normal aging process on the DNA in breast cell genes.

Benign vs. Malignant Breast Cancers

Not all breast tumors are dangerous. Some are benign; they grow slowly, don’t spread outside the breast and are not life threatening. Malignant tumors are cancerous; they grow into surrounding tissue and invade the underarm lymph nodes that give them paths to spread outside the breast to other parts of the body.

Stages of Breast Cancer

With information from physical exams, medical imaging, biopsies and blood tests, breast cancers can be divided into five stages of development based on the size, nature and spread of the cancerous cells.

Breast cancers are ranked on a scale of 0 through IV, with 0 describing noninvasive cancers and IV describing cancers that have spread.

The stages are also based on clinical characteristics including the tumor’s size and whether it has grown into nearby tissue (T); whether it has spread to the lymph nodes (N); or whether it has metastasized beyond the breast (M). In 2018, the T, N, M system was updated with additional cancer characteristics.

Men and Women Get Breast Cancer

While breast cancer affects one out of eight women, it also affects about one in 833 men. It is the most commonly diagnosed cancer in women and is women’s second leading cause of cancer death.

However, the good news is that:

  • The incidence of breast cancer in women is diminishing, partially due to the reduction in the use of hormone replacement therapy after menopause.
  • Death rates from breast cancer have been declining for almost three decades, in part due to better screening, early detection, an increase in awareness and continually improving treatment options.
  • The earlier breast cancer is diagnosed, the better the chances for effective treatment.

Two Types of Breast Cancer

Invasive ductal carcinoma (IDC) – About 80 percent of breast cancers are invasive ductal carcinoma. This means that the cancer began in the breast and is spreading outward. You may or may not have symptoms of IDC, and an abnormal area may show up on a mammogram. Some symptoms include:

  • A lump on the breast or underarm that you or your doctor can feel
  • Breast swelling or pain
  • Skin irritation on the breast or nipple
  • Discharge from the nipple (not milk)

Ductal Carcinoma in Situ (DCIS) – In Situ means “in its original place, and this type of cancer begins in the breast, but hasn’t spread to other parts of the body. While not life-threatening, having DCIS can increase the potential for breast cancer returning in the future.

Breast Cancer Resources

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