Lower BMI may increase risk for lung cancer
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GENEVA — Lower BMI may increase risk for lung cancer, according to results of an ongoing prospective study presented at World Cancer Congress.
The findings — reported from a large cohort in Japan — suggest smoking cessation and maintaining appropriate body weight are critical factors for lung cancer prevention, researchers concluded.
“We conducted this study in Asia, whereas in Western populations, obesity has shown a protective effect,” Sarah K. Abe, PhD, MScPH, section head of the division of prevention at National Cancer Center Institute for Cancer Control in Japan, told Healio. “The clinical implication relates to the importance of looking at specific factors of the population you are studying. We can’t simply make broad statements that exposure to ‘X’ is associated with [a specific outcome]. We need to assess by gender, ethnicity and genetic factors.”
Prior research suggested BMI is inversely associated with lung cancer risk; however, residual confounding by smoking or weight change remains controversial, according to study background. Evidence related to the impact of height on lung cancer risk is limited.
Abe and colleagues assessed the association between anthropometric measurements — specifically BMI, height and body weight change — and lung cancer risk. They also evaluated associations by histologic subtype and cigarette smoking history.
The analysis — which began with baseline data collected in 1990 and 1993 — included 92,098 people (52% women) in the Japan Public Health Center-based Prospective Study.
Investigators performed Cox proportional hazards regression, adjusted for cancer subtypes, smoking status and potential confounders.
They used self-reported baseline weight and height data that were validated through health check-up data.
During mean follow-up of 19.1 years, investigators identified 2,152 new lung cancer cases.
Investigators performed multivariate regression analysis adjusted for age, physical activity, smoking status, alcohol use, fruit/vegetable intake and other factors. They used BMI of 23 kg/m2 to 24.9 kg/m2 as a reference.
Results revealed a positive association among between lower BMI and overall lung cancer risk among men (< 19 kg/m2, HR = 1.48; 95% CI, 1.18-1.85; 19 kg/m2 to 22.9 kg/m2, HR = 1.19; 95% CI, 1.05-1.35).
Results showed no significant association among women in those BMI categories (< 19 kg/m2, HR = 1.11; 95% CI, 0.76-1.62; 19 kg/m2 to 22.9 kg/m2, HR = 1.02; 95% CI, 0.82-1.25), as well as no significant associations among men or women with BMI of 25 kg/m2 or higher.
Results showed elevated risk for adenocarcinoma among those with BMI less than 19 kg/m2, as well as elevated risk for squamous cell carcinoma among men with BMI between 19 kg/m2 and 22.9 kg/m2. Researchers also observed an association between low BMI, weight decrease and squamous cell carcinoma among women.
“For the height portion of the study, overall we saw no significant results, but we did find shorter men had an increased risk for lung cancer,” Abe said.
Researchers also observed no statistically significant association between weight loss and lung cancer risk; however, study participants who lost 5 kilograms — or about 11 pounds — exhibited an increased risk for lung cancer, Abe said.
“Lower BMI may increase risk for lung cancer but, as we all know, lung cancer is driven primarily by smoking,” Abe said. “A meta-analysis conducted in 2015 found similar results to ours that lower BMI increased risk for lung cancer. The EPIC Study found that obesity actually lowered the risk for lung cancer ... but we wouldn’t see those results necessarily in an Asian population because there are very few people with high BMI.”
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Abe S, et al. Abstract 1011. Presented at: World Cancer Congress; Oct. 18-20, 2022; Geneva.
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