Sen. John Edwards’ wife has breast cancer, according to wire reports.

Elizabeth Edwards was diagnosed with invasive ductal breast cancer (search) on Wednesday, according to the Associated Press. This cancer starts in the milk ducts of the breast. Then it breaks through the wall of the duct and invades the fatty tissue of the breast. This is the most common form of breast cancer, accounting for 80 percent of cases.

Edwards, 55, found a lump in her right breast last week. After seeing her family doctor and then a specialist to have a needle biopsy, the breast cancer was confirmed on Wednesday, the AP says.

Doctors are reportedly performing more tests to determine if Edwards’ cancer has spread outside her breast.

Treatment for invasive ductal breast cancer depends on how advanced it is. The main treatment for invasive ductal breast cancer is surgery to remove the cancer.

There are two main types of surgery:

—Breast-conserving surgery — either a lumpectomy or partial mastectomy — to remove part of the breast

—Mastectomy to remove the whole breast

Many women with early-stage cancer opt for breast-conserving surgery. In a lumpectomy (search), only the "lump" of the tumor, as well as a small part of the normal breast tissue closely surrounding the tumor, is removed. In a partial mastectomy, the tumor and a larger portion of surrounding breast tissue are removed.

If the cancer is advanced or if there is a high risk of recurrence, the surgeon may recommend a mastectomy (search), which is complete removal of the breast. The woman should also be informed about her options for breast reconstruction, which sometimes is done right after mastectomy.

At the time of surgery, most women also have either axillary node dissection or sentinel node biopsy to see if cancer has spread to the lymph nodes. These procedures remove lymph nodes from the armpit to test them for cancer cells.

If a woman has a lumpectomy or partial mastectomy, she almost always has radiation therapy, too. If a mastectomy is needed due to the breast cancer being more advanced, chemotherapy is usually also given. Other possibilities include hormone therapy after surgery for women who have gone through menopause to help prevent breast cancer recurrence.

Breast cancer often spreads to other parts of the body before it is detected. In these cases, women may require additional treatment to remove any remaining cancer cells. Sometimes, the additional treatment may be given before surgery if the cancer has spread widely.

By Michael W. Smith, MD, reviewed by Charlotte E. Grayson, MD

SOURCES: Associated Press. WebMD Medical Reference provided in collaboration with The Cleveland Clinic: "Your Guide to Breast Cancer."