TOPLINE

Modifiable lifestyle factors and health conditions accounted for 84% of the male-female disparity in the incidence of non-sex-specific cancer in a Chinese population but only 26% of the gap in a UK population, highlighting the differences in how behavioral and metabolic exposures contribute to the gap across populations.

METHODOLOGY

• Globally, incidence rates of most non-sex-specific cancers are higher among men than among women, but it is unclear how much of this gap can be attributed to modifiable lifestyle- and health-related exposures and whether this varies by population.
• Researchers conducted an individual-level analysis of three population-based prospective cohorts: two in China (the Shanghai Men's Health Study and Shanghai Women's Health Study) and one in the UK  (the UK Biobank). The cohorts included adults aged 40-74 years who never had cancer. 
• A total of 589,766 participants were included: 134,742 from the Chinese cohorts (45.6% men) and 455,024 from the UK Biobank (46.7% men). Baseline data were collected from 1997 to 2010, and 70,300 non-sex-specific cancer cases were documented during follow-up through 2021.
• Researchers examined 11 risk factors, including behaviors (smoking, heavy alcohol drinking, and physical inactivity), diet (low consumption of vegetables and fruit plus high consumption of red meat and processed meat), and health conditions (cholelithiasis, chronic liver diseases, diabetes, and obesity).
• Outcome measures included the age-standardized incidence rates of 34 non-sex-specific cancer endpoints. Attributable rate differences (cases per 100,000 person-years) and attributable proportions (%) were calculated to quantify the male-female incidence rate gap attributable to the exposures. The secondary outcome was mortality from non-sex-specific cancer.

TAKEAWAY

• The male-to-female incidence rate ratio for cancer was higher in the Chinese population than in the UK population (1.66 vs 1.49). The absolute male-female differences in age-standardized incidence rates were 216.15 and 199.62 cases per 100,000 person-years in China and the UK, respectively.
• In the Chinese population, the joint attributable rate difference across the risk factors was 182.52, accounting for 84.44% of the male-female cancer incidence gap. The gap was driven largely by lifestyle factors, with smoking (attributable rate difference, 111.87; attributable proportion, 51.75%), heavy alcohol drinking (attributable rate difference, 32.64; attributable proportion, 15.10%), and chronic liver diseases (attributable rate difference, 21.72; attributable proportion, 10.05%).
• In the UK population, the joint attributable rate difference was 52.31, accounting for only 26.21% of the male-female cancer incidence gap. The gap was driven largely by health conditions, with obesity (attributable rate difference, 15.34; attributable proportion, 7.68%), smoking (attributable rate difference, 12.49; attributable proportion, 6.26%), and diabetes (attributable rate difference, 7.00; attributable proportion, 3.51%) being the leading contributors.
• A total of 26,670 deaths from non-sex-specific cancers were recorded. Mortality rates from non-sex-specific cancers combined were higher in men than in women, with mortality rate ratios of 1.94 and 1.76 in the Chinese and UK populations, respectively. 

IN PRACTICE

"These findings suggest that the contribution of modifiable lifestyle behaviors and health conditions to the male-female cancer gap varies across populations, underscoring the need for population-specific prevention," the authors wrote.

SOURCE

The study was led by Zhuo-Ying Li, PhD, State Key Laboratory of Systems Medicine for Cancer, Shanghai Cancer Institute, Renji Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China. It was published online on September 24 in JAMA Oncology.

LIMITATIONS

The study was limited by potential residual confounding and reverse causation owing to its observational design. Populations from countries other than China and the UK were not studied, limiting the generalizability of the findings. The lack of assessment of changes in risk factors beyond the baseline may have led to exposure misclassification. Data on occupational exposures, ambient air pollution, and specific infectious agents were unavailable. Additional limitations included the use of relative rather than absolute measures for diet and physical activity, differing cancer-screening coverage between the UK and China, underrepresentation of older adults and exclusion of early-onset cancers, limited generalizability due to the urban Chinese sample, UK Biobank's healthy-volunteer bias and predominantly White European composition, and missing race/ethnicity data in the Chinese cohorts.

DISCLOSURES

The study was funded by the National Natural Science Foundation of China, the Shanghai Municipal Bureau of Disease Control and Prevention, the National Key Project of Research and Development Program of China, and the US National Institutes of Health. The authors reported having no conflicts of interest.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.