[How is our practice of mastectomy? Analysis based on population data in a French department]

The objective of this research was to study the evolution of the mastectomy rate in patients with breast cancer between 1998 and 2015, based on population data from the Côte d'Or breast cancer registry of the FRANCIM network ("France cancer incidence and mortality").

In this study on population register we included patients who had presented a primary breast cancer (invasive cancer and/or carcinoma in situ [CIS]) between 1998 and 2015 in the Côte d'Or department. We estimated the annual proportions of mastectomies, then calculated their evolution trends over this period.

Between 1998 and 2015, 7093 patients were included. The overall proportion of mastectomies was stable at 28% and did not respond to a time trend (Sen's slope of 0.2% per year; P=0.289). There was an increase in the proportion of lobular carcinomas (slope at 0.3% per year; P <0.05), with a rising proportion of mastectomy for lobular carcinomas (slope at 0.6% per year; P<0.05) but decreasing for ductal (slope at -0.8% per year; P<0.05). The proportion of mastectomy was stable for plurifocal cancers but the proportion of plurifocal cancers increased over time (slope at 0.8% per year; P<0.05).

Therefore, mastectomy remained a stable practice over the 18 years of analysis in the Côte d'Or region. However, this overall stability is the result of variations in the profiles of diagnosed cancers and surgical practices.