Management of Cancer in the Breast

A. Approximately 20% of breast cancers are non-invasive; incidence of non-invasive cancer is increasing with increasing application of mammography.

1. 1. These lesions are confined to the walls and lumens of ducts (ductal carcinoma in situ or DCIS) or of the lobules (small, terminal ducts) (lobular carcinoma in situ or LCIS).
2. 2. LCIS is more appropriately considered a pre-malignant condition, a marker of increased risk of developing ductal carcinoma anywhere in either breast at an approximate frequency of 1% per year. The management of LCIS is generally close follow-up without specific rx; the only rational alternative is bilateral mastectomy.
3. 3. DCIS is a pre-invasive malignancy with a risk of progression to invasive cancer in that anatomic region of the breast of at least 30%.

a. The NSABP trial suggests lumpectomy (excisional bx) and breast radiation may be an alternative to mastectomy, but follow-up is short (NEJM 1993; 328:1581-86).

b. Uncertain whether wide excision alone, with or without tamoxifen, is a safe and effective alternative that might avoid the need for mastectomy or breast radiation--presently under study.

B. Invasive ductal or lobular breast cancer (infiltrating ductal or lobular carcinoma)

1. Primary radiation therapy following lumpectomy is equivalent to mastectomy in disease-free and overall survival.
2. Patients with extensive DCIS in addition to invasive cancer, those with an occult primary tumor, and those whose potential for a good cosmetic outcome with breast conservation has been decreased by excisional bx (e.g. large tumor in a small breast) are better candidates for mastectomy, with or without reconstruction which may be done immediately.
3. Chest wall radiation after mastectomy will decrease local recurrence but does not improve overall survival. This is usually reserved for patients with 4 or more positive axillary nodes, in whom the risk of local recurrence despite mastectomy is high.