Dr. de Blok explained that their analysis compared the observed cases in both transgender men and women to the expected number of cases for the same number of males and females, yielding two standardized incidence ratios (SIRs) for each transgender group.
For transgender women, the SIR for breast cancer compared with males was 50.9 (95% confidence interval, 30.1-80.9). The SIR compared to females was 0.3 (95% CI, 0.2-0.4). This reflected the expected case number of 0.3 for males and the 58 expected cases for a matched group of females.
For transgender men, the SIR for breast cancer compared with males was 59.8 (95% CI, 19-144.3), while the SIR compared to females was 0.2 (95% CI, 0.1-0.5). The expected cases for a similar group of males would be 0.1, and for females, 18.
In many cases, whether a transgender person receives standardized screening mammogram reminders will depend on which sex is assigned to that individual in insurance and other administrative databases, Mr. de Blok noted. When electronic health records and other databases have a binary system, at-risk individuals may fall through the cracks.
Dr. de Blok reported no conflicts of interest.
SOURCE: de Blok C, et al. ENDO 2018, abstract OR 25-6.