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Background: Transgender and gender diverse (TGD) individuals experience an incongruence between their assigned birth sex and gender identity. They may have a higher prevalence of health conditions associated with cancer risk than cisgender people. Aim: To examine the prevalence of several cancer risk factors among TGD individuals compared with cisgender individuals. Design and setting: A cross-sectional analysis was conducted using data from the UK's Clinical Practice Research Datalink to identify TGD individuals between 1988–2020, matched to 20 cisgender men and 20 cisgender women on index date (date of diagnosis with gender incongruence), practice, and index age (age at index date). Assigned birth sex was determined from gender-affirming hormone use and procedures, and sex-specific diagnoses documented in the medical record. Method: The prevalence of each cancer risk factor was calculated and the prevalence ratio by gender identity was estimated using log binomial or Poisson regression models adjusted for age and year at study entry, and obesity where appropriate. Results: There were 3474 transfeminine (assigned male at birth) individuals, 3591 transmasculine (assigned female at birth) individuals, 131 747 cisgender men, and 131 827 cisgender women. Transmasculine people had the highest prevalence of obesity (27.5%) and 'ever smoking' (60.2%). Transfeminine people had the highest prevalence of dyslipidaemia (15.1%), diabetes (5.4%), hepatitis C infection (0.7%), hepatitis B infection (0.4%), and HIV infection (0.8%). These prevalence estimates remained elevated in the TGD populations compared with cisgender persons in the multivariable models. Conclusion: Multiple cancer risk factors are more prevalent among TGD individuals compared with cisgender individuals. Future research should examine how minority stress contributes to the increased prevalence of cancer risk factors in this population. [ABSTRACT FROM AUTHOR]

Myotonic dystrophy type I (DM1) is an autosomal dominant multisystem disorder characterized by myotonia and muscle weakness. Type 2 diabetes (T2D) and cancer have been shown to be part of the DM1 phenotype. Metformin, a well‐established agent for the management of T2D, is thought to have cancer‐preventive effects in the general population. In our study, we aimed to assess the association between T2D, metformin use and the risk of cancer in DM1 patients. We identified a cohort of 913 DM1 patients and an age‐, sex‐ and clinic‐matched cohort of 12,318 DM1‐free controls from the UK Clinical Practice Research Datalink, a large primary care records database. We used Cox regression models to assess cancer risk in T2D patients who were metformin users or nonusers compared to patients without T2D. Separate analyses were conducted for DM1 patients and controls. T2D was more prevalent in DM1 than in controls (8% vs. 3%, p < 0.0001). DM1 patients with T2D, compared to those without T2D, were more likely to develop cancer (hazard ratio [HR] = 3.60, 95% confidence interval [CI] = 1.18–10.97; p = 0.02), but not if they were treated with metformin (HR = 0.43, 95% CI = 0.06–3.35; p = 0.42). Among controls, we observed no significant associations between T2D and cancer risk in either users or nonusers of Metformin (HR = 1.28, 95% CI = 0.91–1.79; p = 0.16 and HR = 1.13, 95% CI = 0.72–1.79; p = 0.59, respectively). These results show an association between T2D and cancer risk in DM1 patients and may provide new insights into the possible benefits of Metformin use in DM1. What's new? Recent evidence suggests that myotonic dystrophy type I (DM1), an inherited nucleotide repeat disorder, is a cancer predisposition syndrome. However, the underlying pathological mechanisms and cancer‐predisposing risk factors remain unknown. Here, type 2 diabetes (T2D) and metformin were investigated for potential associations with cancer risk in DM1 patients. T2D was found to be more prevalent in DM1 patients than controls. DM1 patients with T2D were at increased risk of developing cancer. By contrast, cancer risk was not elevated in DM1‐T2D patients taking metformin. Further investigation of metformin use and cancer in DM1 patients could yield important insights into DM1‐related cancer prevention. [ABSTRACT FROM AUTHOR]

Objectives: Recent evidence showed that myotonic dystrophy type I (DM1) patients are at increased risk of certain cancers, but the risk of benign tumors is unknown. We compared the risk of benign tumors in DM1 patients with matched DM1‐free individuals and assessed the association between benign tumors and subsequent cancers. Methods: We identified 927 DM1 patients and 13,085 DM1‐free individuals matched on gender, birth‐year, clinic, and clinic‐registration year from the UK Clinical Practice Research Datalink, a primary care records database. We used Cox regression models for statistical analyses. Results: DM1 patients had elevated risks of thyroid nodules (Hazard Ratio [HR] = 10.4; 95% Confidence Interval [CI] = 3.91–27.52; P < 0.001), benign tumors of the brain or nervous system (HR = 8.4; 95% CI = 2.48–28.47; P < 0.001), colorectal polyps (HR = 4.3; 95% CI = 1.76–10.41; P = 0.001), and possibly uterine fibroids (HR = 2.7; 95% CI = 1.22–5.88; P = 0.01). Pilomatricomas and salivary gland adenomas occurred almost exclusively in DM1 patients (Fisher's exact P < 0.001). The HR for colorectal polyps was elevated in DM1 males but not in females (HR = 8.2 vs. 1.3, respectively; P‐heterogeneity < 0.001), whereas endocrine and brain tumors occurred exclusively in females. The data suggested an association between benign tumors and subsequent cancer in classic DM1 patients (HR = 2.7; 95% CI = 0.93–7.59; P = 0.07). Interpretation: Our study showed a similar site‐specific benign tumor profile to that previously reported for DM1‐associated cancers. The possible association between benign tumors and subsequent cancer in classic DM1 patients warrants further investigation as it may guide identifying patients at elevated risk of cancer. Our findings underscore the importance of following population‐based screening recommendations in DM1 patients, for example, for colorectal cancer. [ABSTRACT FROM AUTHOR]