Smoking, Solid Fuel Use for Cooking, and Cancer Mortality: A Prospective Cohort Study in Southwestern China

Smoking and solid fuel are common exposures among Chinese adults, yet evidence regarding their associations with cancer mortality remains inconsistent, and their joint effects are insufficiently studied. Using data from the Pengzhou site of the China Kadoorie Biobank in Sichuan Province, we applied Cox proportional hazards models to examine associations of smoking, cooking fuel use, and co-exposure with mortality from overall cancer and major site-specific cancers. Among 55,404 participants, 61.63% were women, 75.15% reported cooking, and 46.38% reported smoking; 2030 cancer deaths occurred during follow-up. Current smoking and solid fuel cooking were associated with 27% and 18% higher risks of overall cancer mortality. Initiation before 18 years increased overall cancer mortality by 37%, esophageal cancer mortality by 107%, and lung cancer mortality by 86%. Higher daily cigarette consumption, longer smoking duration, and greater cumulative smoking were each positively associated with mortality from overall cancer, esophageal cancer, and lung cancer. Compared with individuals who neither smoked nor used solid fuels, solid fuel use alone increased overall cancer mortality by 24%, while smoking alone increased overall mortality by 32% and esophageal cancer mortality by 144%. Individuals exposed to both smoking and solid fuel use had higher mortality risks, reaching 49% for overall cancer, 198% for esophageal cancer, and 94% for lung cancer. These findings highlight the critical importance of quitting smoking and promoting clean cooking fuels for cancer prevention.