Gender-affirming mastectomy in transmasculine individuals in The Netherlands: A large cohort study on outcomes and trends.

Gender-affirming mastectomy is frequently performed in transmasculine individuals. The aim of this study is to describe surgical and demographic trends and outcomes in a large group of individuals undergoing this procedure. All individuals who underwent gender-affirming mastectomy from 01-1990 to 01-2023 in our center were identified. A retrospective chart study was conducted, recording medical history, use of medication including hormones, puberty suppression, surgical history, preoperative chest characteristics, BMI at surgery, surgical technique, concurrent surgical procedures, resection weight, complications and re-operations. Procedural, demographic and surgical trends were analyzed. A total of 2030 individuals were included of whom 1350 (67%) underwent double incision, 551 (27%) donut, 67 (3%) peri-areolar, 55 (3%) batwing and 7 (<1%) another mastectomy technique. A steep increase of performed mastectomies was observed in recent years. The mean age of people undergoing this procedure is increasingly lower. Surgical trend analysis showed: an increase in the use of the double incision technique, a smaller chest was deemed eligible for donut mastectomy and a less frequent use of a pedicled nipple-areolar complex. Postoperative bleeding that required a reoperation under general anesthesia occurred in 142 (7.0%) individuals (6.3% after double incision, 7.1% after donut, 14.9% after peri-areolar and 12.8% following batwing mastectomy). One or multiple surgical corrections were performed in 19.9% after double incision, 31.2% after donut, 14.9% after peri-areolar and 32.7% following batwing mastectomy. The median clinical follow-up time was 3.2 years (IQR 0.6-6.4). The frequency of performed mastectomy procedures has increased drastically over recent years. Specific surgical and demographic trends were identified.