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Breast cancer is uncommon in men and knowledge about its causation limited. Obesity is a risk factor but there has been no investigation of whether weight change is an independent risk factor, as it is in women. In a national case‐control study, 1998 men with breast cancer incident in England and Wales during 2005 to 2017 and 1597 male controls were interviewed about risk factors for breast cancer including anthropometric factors at several ages. Relative risks of breast cancer in relation to changes in body mass index (BMI) and waist/height ratios at these ages were obtained by logistic regression modelling. There were significant trends of increasing breast cancer risk with increase in BMI from age 20 to 40 (odds ratio [OR] 1.11 [95% confidence interval (CI) 1.05‐1.17] per 2 kg/m2 increase in BMI; P <.001), and from age 40 to 60 (OR 1.12 [1.04‐1.20]; P =.003), and with increase in self‐reported adiposity compared to peers at age 11 to BMI compared with peers at age 20 (OR 1.19 [1.09‐1.30]; P <.001). Increase in waist/height ratio from age 20 to 5 years before diagnosis was also highly significantly associated with risk (OR 1.13 [1.08‐1.19]; P <.001). The associations with increases in BMI and waist/height ratio were significant independently of each other and of BMI or waist/height ratio at the start of the period of change analysed, and effects were similar for invasive and in situ tumours separately. Increases in BMI and abdominal obesity are each risk factors for breast cancer in men, independently of obesity per se. These associations might relate to increasing oestrogen levels with weight gain, but this needs investigation. What's new? Although obesity is an established risk factor for breast cancer in men, there have been no investigations of whether weight change is an independent risk factor, as it is in women. In an interview case‐control study including 1998 cases and 1597 controls, authors found that increase in body mass index and in abdominal obesity are each significant risk factors for breast cancer in men, independent of obesity per se. [ABSTRACT FROM AUTHOR]

Purpose: Breast cancer is uncommon in men and its aetiology is largely unknown, reflecting the limited size of studies thus far conducted. In general, number of children fathered has been found a risk factor inconsistently, and infertility not. We therefore investigated in a case-control study, the relation of risk of breast cancer in men to infertility and number of children., Patients and Methods: We conducted a national case-control study in England and Wales, interviewing 1998 cases incident 2005-17 and 1597 male controls, which included questions on infertility and offspring., Results: Risk of breast cancer was statistically significantly associated with male-origin infertility (OR = 2.03 (95% confidence interval (CI) 1.18-3.49)) but not if a couple's infertility had been diagnosed as of origin from the female partner (OR = 0.86 (0.51-1.45)). Risk was statistically significantly raised for men who had not fathered any children (OR = 1.50 (95% CI 1.21-1.86)) compared with men who were fathers. These associations were statistically significantly present for invasive tumours but not statistically significant for in situ tumours., Conclusion: Our data give strong evidence that risk of breast cancer is increased for men who are infertile. The reason is not clear and needs investigation., (© 2022. The Author(s).)

Background: Breast cancer is rare in men, and information on its causes is very limited from studies that have generally been small. Adult obesity has been shown as a risk factor, but more detailed anthropometric relations have not been investigated., Methods: We conducted an interview population-based case-control study of breast cancer in men in England and Wales including 1998 cases incident during 2005-2017 at ages younger than 80 years and 1597 male controls, with questions asked about a range of anthropometric variables at several ages. All tests of statistical significance were 2-sided., Results: Risk of breast cancer statistically significantly increased with increasing body mass index (BMI) at ages 20 (odds ratio [OR] = 1.07, 95% confidence interval [CI] = 1.02 to 1.12 per 2-unit change in BMI), 40 (OR = 1.11, 95% CI = 1.07 to 1.16), and 60 (OR = 1.14, 95% CI = 1.09 to 1.19) years, but there was also an indication of raised risk for the lowest BMIs. Large waist circumference 5 years before interview was more strongly associated than was BMI with risk, and each showed independent associations. Associations were similar for invasive and in situ tumors separately and stronger for HER2-positive than HER2-negative tumors. Of the tumors, 99% were estrogen receptor positive., Conclusions: Obesity at all adult ages, particularly recent abdominal obesity, is associated with raised risk of breast cancer in men, probably because of the conversion of testosterone to estrogen by aromatase in adipose tissue. The association is particularly strong for HER2-expressing tumors., (© The Author(s) 2021. Published by Oxford University Press.)

Background: Large population-based cohort studies in areas of high hepatitis B virus (HBV) prevalence have provided the evidence establishing hepatitis B surface antigen (HBsAg) carriage as a risk factor for hepatocellular carcinoma (HCC) and liver disease. Fewer studies have examined this in Western countries, where both HBV infection and carriage are less common and transmission patterns differ. This is the only prospective population-based study to examine this relationship in Europe., Methods: In all, 2681 male and 977 female blood donors in England and Wales, found to be HBsAg positive during routine blood-donation screening, were followed up from recruitment in 1970-1982 to December 1999 and their cause-specific mortality was analysed. This was compared with that of the general population of England and Wales., Results: During a mean of 22 years of follow-up, 17.4% of the 420 deaths were due to HCC or liver disease. There were 20 deaths from HCC in male HBsAg carriers, representing a significantly high standardized mortality ratio (SMR) compared to the male population of England and Wales of 26 (SMR = 26.26; 95% CI: 16.04- 40.54). The HCC incidence rate in males was 33.5 per 100 000 person years and 4.4 per 100 000 person years in females. Men had 8.5 (SMR = 8.50; 95% CI: 6.25- 11.31) and women had 3.9 times the risk of death from liver disease (SMR = 3.89; 95% CI: 1.26-9.09). The risk of circulatory disease deaths was reduced in both males and females. There was a significant increased risk of non-Hodgkins lymphoma that was not apparent in the first decade of follow-up. The increased risk of HCC and liver disease in men fell with follow-up., Conclusion: Hepatitis B surface antigen carriage is a significant risk factor in England and Wales for both liver disease and HCC mortality. However, this risk has declined with duration of follow-up. This could be due to natural reversion to HBsAg negativity or as a result of treatment and avoidance of other risk factors. The increased risk of non-Hodgkins lymphoma seen in longer follow-up is likely to be related to HIV infection acquired subsequent to recruitment.