Each breast cancer patient is different, and no one answer will work for everyone.
With a mastectomy, the breast, nipple, areola and a small amount of skin are removed along with one or two lymph nodes. A lumpectomy is removal of the tumor only — no skin or nipple tissue.
With a mastectomy, there is an option for breast reconstruction. With a lumpectomy, radiation therapy is needed in most cases.
Despite advances in decreasing the extent of surgery needed, there actually has been during the past decade an increase in mastectomy rates compared to lumpectomy, particularly double mastectomy, in which the unaffected breast is also removed.
Patients themselves are increasingly asking for double mastectomies. Reasons include improvements in reconstruction through plastic surgery, mandated coverage by third-party payers for these procedures, and increased use of digital mammograms and MRI, which can find other suspicious areas in the breasts.
There is also a tendency to overestimate risk of second breast cancers and a general assumption that more surgery must be better. Others think the continued need for mammograms is very stressful. Some worry about the cancer "spreading" to the other breast, even though that does not happen.
The only patients who definitely should not have a lumpectomy are those with very large, multiple or diffuse cancers involving more than one quadrant of the breast, and those who have had or can't tolerate radiation therapy. Mastectomy, particularly double mastectomy, is often suggested to the small minority of patients who have a positive BRCA test, whose risk of second cancers is high.
The most important fact is that there is no difference in the chances of survival between those who have lumpectomy and those who have mastectomy, assuming there are no factors making breast conservation inadvisable.
Survival is determined solely by the characteristics of the cancer itself, assuming one gets appropriate treatment. Breast cancer kills only when it has spread to other parts of the body, so the presence or absence of the breast makes no difference.
There is really no wrong decision, and patients should do what they are comfortable with. If they wish to preserve their breast appearance, want minimal downtime and don't mind radiation treatments, then lumpectomy is for them. If they don't care whether the breast is saved and have concerns about radiation or continued mammograms, then mastectomy might be the way to go. Either way, the cancer is taken away, with is the main goal.