ObjectiveTo investigate the incidence and characteristics of breast cancer in transgender people in the Netherlands compared with the general Dutch population.DesignRetrospective, nationwide cohort study.SettingSpecialised tertiary gender clinic in Amsterdam, the Netherlands.Participants2260 adult trans women (male sex assigned at birth, female gender identity) and 1229 adult trans men (female sex assigned at birth, male gender identity) who received gender affirming hormone treatment.Main outcome measuresIncidence and characteristics (eg, histology, hormone receptor status) of breast cancer in transgender people.ResultsThe total person time in this cohort was 33 991 years for trans women and 14 883 years for trans men. In the 2260 trans women in the cohort, 15 cases of invasive breast cancer were identified (median duration of hormone treatment 18 years, range 7-37 years). This was 46-fold higher than in cisgender men (standardised incidence ratio 46.7, 95% confidence interval 27.2 to 75.4) but lower than in cisgender women (0.3, 0.2 to 0.4). Most tumours were of ductal origin and oestrogen and progesterone receptor positive, and 8.3% were human epidermal growth factor 2 (HER2) positive. In 1229 trans men, four cases of invasive breast cancer were identified (median duration of hormone treatment 15 years, range 2-17 years). This was lower than expected compared with cisgender women (standardised incidence ratio 0.2, 95% confidence interval 0.1 to 0.5).ConclusionsThis study showed an increased risk of breast cancer in trans women compared with cisgender men, and a lower risk in trans men compared with cisgender women. In trans women, the risk of breast cancer increased during a relatively short duration of hormone treatment and the characteristics of the breast cancer resembled a more female pattern. These results suggest that breast cancer screening guidelines for cisgender people are sufficient for transgender people using hormone treatment.

Clear cell-type renal cell carcinomas (clear RCC) are characterized almost universally by loss of heterozygosity on chromosome 3p, which usually involves any combination of three regions: 3p25-p26 (harboring the VHL gene), 3p12-p14.2 (containing the FHIT gene), and 3p21-p22, implying inactivation of the resident tumorsuppressor genes (TSGs). For the 3p21-p22 region, the affected TSGs remain, at present, unknown. Recently, the RAS association family 1 gene (isoform RASSF1A), located at 3p21.3, has been identified as a candidate lung and breast TSG. In this report, we demonstrate aberrant silencing by hypermethylation of RASSF1A in both VHL-caused clear RCC tumors and clear RCC without VHL inactivation. We found hypermethylation of RASSF1A's GC-rich putative promoter region in most of analyzed samples, including 39 of 43 primary tumors (91%). The promoter was methylated partially or completely in all 18 RCC cell lines analyzed. Methylation of the GC-rich putative RASSF1A promoter region and loss of transcription of the corresponding mRNA were related causally. RASSF1A expression was reactivated after treatment with 5-aza-2 -deoxycytidine. Forced expression of RASSF1A transcripts in KRC͞Y, a renal carcinoma cell line containing a normal and expressed VHL gene, suppressed growth on plastic dishes and anchorage-independent colony formation in soft agar. Mutant RASSF1A had reduced growth suppression activity significantly. These data suggest that RASSF1A is the candidate renal TSG gene for the 3p21.3 region. L oss of heterozygosity (LOH) of chromosome 3p is the most common event in clear cell-type renal cell carcinomas (clear RCC). It involves one or more of the three major commonly deleted regions (1-3) that may be subdivided further by using pioneering stringent criteria for LOH analysis (4-6).The most frequent form of hereditary RCC is the familial VHL cancer syndrome (7). The VHL gene was mapped to 3p25 and was isolated by positional cloning (8). It was inactivated by intragenic and genomic deletions and various kinds of mutations in 100% of analyzed VHL families and in a large portion of sporadic clear RCC (9). Inactivation of VHL by promoter hypermethylation (10) in sporadic clear RCC was noted also and was observed quite frequently (20%). However, in other sporadic clear RCC (reaching in some studies 30-50%) and some non-VHL clear RCC families (11, 12), VHL was not affected (see review in ref. 13).Another commonly deleted region was found at 3p12-p14. Although the overall frequency of the specific LOH is not high, chromosome transfer experiments indicated that the 3p12-p14 region could suppress the tumorigenic properties of some clear RCC cell lines (14), implying the presence of a gene or genes involved in the origin and͞or development of clear RCC. This role may be attributed to the FHIT gene at 3p14.3 (15), and͞or other tumor-suppressor genes (TSGs) residing in 3p12.Multiple studies have identified LOH on 3p21-p22 as the most frequent 3p loss in renal tumor development (4,5,16,17). Recent data indicate that ...