SO11. Risk of Lymphomas of the Breast Following Breast Reconstruction

PURPOSE: The US Food and Drug Administration (FDA) recently issued a safety communication for reports of various lymphomas of the breast that developed in association with breast implants and were distinct from BIA-ALCL. We investigate the risk of non-BIA-ALCL breast lymphomas in a population of women who have undergone implant reconstruction after mastectomy for breast cancer. METHODS: We identified women who underwent mastectomy with implant-based reconstruction for tumors within the breast using the SEER 17 database (2000-2020). Multiple primary-standardized incidence ratios (SIR) were used to compare the number of observed versus expected cases of ALCL and non-ALCL breast lymphomas diagnosed in the study population. RESULTS: The final cohort comprised 61,043 women who were followed for 478,864 person-years. There were 7 observed cases of breast ALCL (SIR 43.7, 95%CI 17.6-90.1) and 8 cases of other lymphomas of the breast (SIR 2.94, 95%CI 1.27-5.80). In comparison, the risk of developing lymphomas outside of the breast was not elevated (SIR 0.98, 95%CI 0.86-1.11). Of the 8 cases of other breast lymphomas, 5 were diffuse large B-cell, 2 were small lymphocytic, and 1 was peripheral T-cell, not otherwise specified. CONCLUSION: To our knowledge, this is the first report of an increased risk of non-ALCL breast lymphomas after breast implantation. The absolute excess risk is similar to that of breast ALCL. These findings may inform future guidance from regulatory agencies.