Geographical analysis of thyroid cancer in young people from northern England: Evidence for a sustained excess in females in Cumbria

A previous study found a thyroid cancer excess in Cumbria following the Chernobyl explosion, but did not analyse sex-specific effects. This study examines sex differences in the incidence of thyroid cancer. Ninety-five primary thyroid carcinomas (69 females, 26 males) diagnosed in those aged 0–24 during 1968–2005 were identified from the Northern Region Young Persons’ Malignant Disease Registry. Age-standardised incidence rates (ASRs), rate ratios (RRs) and 95% confidence intervals (CIs) were calculated.For males, the ASR was 0.6 per million person-years during the pre-Chernobyl period (1968–1986), and was 1.8 per million person-years during the post-Chernobyl period (1987–2005). For females, the ASR was 2.4 pre-Chernobyl and was 3.9 post-Chernobyl. The previously noted excess in Cumbria was entirely confined to females (Cumbrian females: RR for post-Chernobyl compared with pre-Chernobyl = 10.8; 95% CI: 1.4–85.3). These findings may be consistent with sex-specific differences in susceptibility to an environmental exposure, such as fallout from the Chernobyl nuclear accident.