Interaction between asthma and overweight/obesity on cancer results from the National Health and Nutrition Examination Survey 2005‐2018

Background and Aims: Asthma, overweight/obesity, and cancer are closely related major public health problems. This study aimed to investigate the interaction between asthma and overweight/obesity on the cancer risk. Methods: We analyzed data from the National Health and Nutrition Examination Survey 2005-2018. Participants ages ≥ 20 years with information on asthma status, body mass index (BMI), and cancer diagnosis were included. Multivariate logistic regression models adjusted for relevant covariates were used to examine the associations among asthma, overweight/obesity, and cancer risk. In addition, we assessed the additive interaction between asthma and overweight/obesity on the cancer risk by using measures, including the relative excess risk due to interaction (RERI), attributable proportion of interaction (AP), and synergy index (S). Results: In total, 26,320 participants met the inclusion criteria. Asthma was associated with an increased risk of cancer (odds ratio [OR] 1.37 [95% confidence interval {CI}, 1.17-1.59]), whereas overweight/obesity (BMI ≥ 25 kg/m²) was also significantly associated with an elevated cancer risk (OR 1.97 [95% CI, 1.32-2.94]). Notably, a significant interaction between asthma and overweight/obesity was observed in relation to the cancer risk (RERI 0.49 [95% CI, 0.02-0.96]; AP 0.20 [95% CI, 0.04, 0.37]; S 1.53 [95% CI, 1.01-2.32]). Conclusion: Our findings demonstrated a synergistic interaction between asthma and overweight/obesity on the cancer risk. The combined effect of asthma and overweight/obesity on the cancer risk exceeded the sum of their individual effects.