A database of women who underwent treatment for invasive lobular carcinoma (ILC) of the breast measuring ≥ 4 cm in size at the University of California, San Francisco between 1994 and 2019 was evaluated.  The cross-sectional analysis examined if the choice of surgical technique, either breast conservation therapy (lumpectomy with or without local tissue rearrangement or oncoplastic reduction mammoplasty) or mastectomy, had an influence on the recurrence-free survival or locoregional recurrence in these patients. Women with tumor size less than 4 cm, de novo stage 4 disease, less than six months of follow-up or lack of data about radiotherapy or tumor size were not included in the study.

Recurrence-free survival at 5 years and 10 years was the primary outcome, while the time to locoregional recurrence and final positive margin rate was taken as the secondary outcome measure.

Thirty women had breast conservation therapy and 150 had mastectomy with or without radiation therapy done for invasive lobular carcinoma. Evidence has shown that younger patients undergo mastectomy more often. In this study too patients who underwent mastectomy were younger (56.6 vs. 64.3 years, p = 0.003) and had larger tumors (7.2 vs. 5.4 cm, p < 0.001) than women undergoing breast conservation therapy. No difference in the recurrence-free survival at 5 or 10 years was observed between the two treatment groups; but an association of recurrent-free survival with tumor size, nodal stage, receptor subtype and margin status was observed. The study concluded that breast conservation therapy can be safely done in patients with invasive lobular carcinoma that is ≥ 4 cm in size provided margins are negative. The authors opine that their findings can help to make an informed decision about the type of surgery for invasive lobular carcinoma.