Occupation and Lymphoma Risk by Cell of Origin: A Nationwide Matched Case-Control Study in Thailand

Lymphoma constitutes a substantial and increasing burden of hematologic malignancy in Thailand and globally, while its etiology remains incompletely characterized. Occupational factors have been implicated in lymphomagenesis; however, evidence from developing countries remains limited, particularly with respect to lymphoma heterogeneity by cell of origin. A matched case-control study was conducted to examine associations between occupational categories and lymphoma risk within a cell-of-origin framework. Occupational categories were defined a priori based on epidemiological evidence and occupational carcinogen classifications of the International Agency for Research on Cancer. The analysis included 592 matched case-control pairs and used conditional logistic regression to estimate adjusted odds ratios (AORs) and 95% confidence intervals (CIs). Diffuse large B-cell lymphoma was the most frequent histological subtype. Agricultural occupations, including agricultural workers, gardeners, and livestock handlers, were associated with increased overall lymphoma risk after adjustment for potential confounders (AOR = 1.41; 95% CI: 1.04-1.90). In prespecified subgroup analyses by cell of origin, associations were observed for B-cell-derived malignancies, including combined B-cell non-Hodgkin lymphoma and Hodgkin lymphoma (AOR = 1.50; 95% CI: 1.04-2.15) and B-cell non-Hodgkin lymphoma alone (AOR = 1.63; 95% CI: 1.09-2.43). Longer duration of agricultural work and initiation of agricultural work during childhood were also associated with increased lymphoma risk. These findings provide epidemiological evidence of an association between agricultural occupation and lymphoma, with similar associations observed in analyses of B-cell-derived malignancies. The results support further investigation of specific agricultural exposures and may inform occupational cancer surveillance and prevention in agricultural populations.