Lumpectomy (sometimes known as a tylectomy) is a surgical removal of a discrete portion or "lump" of breast, usually in the treatment of malignant tumor or breast cancer. It is considered a viable breast conservation therapy, as the amount of tissue removed is limited compared to a full-breast mastectomy, and thus may have physical and emotional advantages over more disfiguring treatment. According to the National Comprehensive Cancer Network guidelines, lumpectomy may be performed for ductal carcinoma in situ (DCIS), for invasive ductal carcinoma, or for other conditions.
DCIS, or intraductal carcinoma, is by definition a breast cancer that is limited to the lining of the milk ducts, and accounts for about 20% of breast cancer in the US. Although early treatment of DCIS was similar to invasive breast cancer, involving full mastectomy and sometimes lymph node dissection, an evolution in understanding about the different kinds of breast cancer prompted investigations into the adequacy of less extreme surgical treatments. The results of an eight-year randomized clinical trial in the late 1980s showed that, although lumpectomy alone was associated with significant recurrence, lumpectomy with local radiation therapy achieved similar outcomes to total mastectomy in treatment of DCIS. This was the first substantial data that showed that so-called "breast conserving therapy" was a real possibility.
After a lumpectomy is performed for DCIS, local radiation therapy is typically performed to help eliminate microscopic-level disease. Axillary sentinel lymph node biopsy, as a method of screening for metastatic disease in otherwise non-invasive DCIS, is falling out of favor because the risks of procedure outweigh any effect on outcomes. For DCIS, chemotherapy is not recommended, but tamoxifen may be recommended for tumors which contain an abundance of estrogen receptors.
For patients with invasive ductal carcinoma who have lumpectomies, lymph node biopsy and radiation therapy are usually recommended. Adjuvant chemotherapy is often recommended, but it may not be recommended if the tumor is small and there are no lymph node metastases. For larger tumors, neoadjuvant chemotherapy may be recommended.
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^Fisher B, Redmond C, Poisson R et al. (1989). "Eight-year results of a randomized clinical trial comparing total mastectomy and lumpectomy with or without irradiation in the treatment of breast cancer". N Engl J Med320: 822–828. doi:10.1056/nejm198903303201302.CS1 maint: Explicit use of et al. (link)