Once you have been diagnosed with breast cancer, usually treatment starts first with surgery. There are generally two components to the operation: 1) the breast, and 2) the axilla (armpit).
In the breast, there are two choices: 1) lumpectomy (removing the cancer lump and some surrounding tissue), or 2) mastectomy (removing the entire breast). Just a quarter of a century ago, almost all patients had mastectomy, even if their breast cancer is small. But over the past few decades, it has been demonstrated that for small cancers, lumpectomy followed by radiation treatment is just as good as mastectomy. Now, “small” is a relative term. The goal of a lumpectomy is that the breast would still look like a breast after all the treatment is done. In someone with small breasts, a “small” cancer may occupy a significant portion of her breast. An adequate lumpectomy in this case may result in an unacceptable cosmetic outcome, and the patient may actually prefer having mastectomy with plastic surgery reconstruction. Another factor is the number of cancers in the breast. Usually, mastectomy is required for multifocal cancer (cancer discovered in two or more locations in the same breast)
At the same time as the breast operation, surgery in the axilla also is carried out for invasive (or infiltrating) breast cancer, as well as in selected cases of DCIS (ductal carcinoma in situ). This is done to determine whether the breast cancer has spread to the lymph nodes in the axilla. In general, there are two choices: 1) sentinel node resection, or 2) axillary node dissection. In sentinel node resection, the surgeon maps the lymphatic drainage of the breast cancer to the first lymph node that receives this lymph, i.e. the sentinel node(s). Only a few (1-3) nodes are then usually removed. In axillary node dissection, more lymph nodes are resected, usually 8-25. Sentinel node resection is a good choice for small early cancer that is unlikely to have spread to the axilla. When the suspicion for cancer already in lymph nodes is high, then full axillary node dissection should be performed.
The above are only general guidelines. No two breast cancer patients are exactly alike, and therefore the decision making process is different and unique for each individual person. Regardless of any one else’s advice, you should make the choice that you personally will be able to live with for the rest of your life.