Background Despite widespread use of bidi and other tobacco products in India, multicentre studies examining product-specific risks for cancer remain limited. This study aimed to determine association of bidi smoking and tobacco-use patterns (exclusive, dual, and poly-tobacco use) in relation to cancer risk, metastatic presentation and treatment modalities. Methods This hospital-based unmatched case-control study was conducted across eight tertiary-care centres in seven Indian states (2024–2025). Cases were recruited based on histologically confirmed cancer and controls were selected based on no prior history of cancer. Individuals with severe illness, or inability to provide reliable information were excluded. Associations were assessed using Firth-penalised logistic regression and adjusted for confounders. Findings Among 4500 screened, 2037 cases (1143 females, 894 males) and 2066 controls (553 females, 1513 males) were enrolled. Tobacco use was reported by 608 cases (29.8%) and 364 controls (17.6%). Compared with non-tobacco users, exclusive bidi smokers (82 cases, 30 controls) had three times higher odds (adjusted Odds Ratio aOR 3.11 95% CI 1.86–5.31), smokeless tobacco users had (329 cases, 260 controls) 1.5 times higher odds (aOR 1.55 95% CI 1.24–1.95), dual bidi-smokeless users nearly four times higher odds (aOR 3.88 95% CI 2.11–7.36), and poly-tobacco users over four times higher odds of any cancer (aOR 4.54 95% CI 2.65–7.88). Bidi duration (≥10 years) (aOR 6.75 4.43–10.47) and number of bidis (≥10 bidis/day) (aOR 7.19 4.57–11.51) were also associated with increased cancer risk. Tobacco use was also significantly associated with metastatic presentation and treatment outcomes. Interpretation Bidi smoking and its combinations with other tobacco products showed strong associations with cancer risk, while other tobacco-use patterns also demonstrated significant associations; however, findings should be interpreted cautiously due to the observational design. These findings support the need for strengthened bidi regulation and targeted tobacco cessation policies. Funding This work was supported with funding from Bloomberg Philanthropies Bloomberg Initiative to Reduce Tobacco Use.
Venkatesh et al. (Mon,) studied this question.
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