Cancer incidence in agricultural cohorts

Abstract

TPS 791: Occupational health 1, Exhibition Hall, Ground floor, August 26, 2019, 3:00 PM - 4:30 PM Background/Aim. An international consortium of agricultural cohort studies, AGRICOH, was established to study cancer and other health outcomes in relation to agricultural exposures. The present analysis aimed to compare the cancer incidence rates between AGRICOH cohorts and the general population. Methods. The analysis included eight AGRICOH cohorts from six different countries. These cohorts varied in size and types of workers included: active and retired agricultural workers, farm owners, and pesticide applicators. From each cohort, information on primary incident cancers (excluding non-melanoma skin cancer), person-years of follow-up, and national/regional cancer rates was obtained. With this information, cohort- and sex-specific standardized incidence ratios (SIRs) and 95% confidence intervals (CIs) were calculated for each cancer site and all cancers combined. Random effects meta-analysis of SIR was then performed when five or more cases were observed in at least four (women) or five (men) of the cohorts. Results. During >3,000,000 person-years, 26,054 cancers were diagnosed. Overall, the meta-SIR was 0.70 (95% CI=0.57-0.84) in women and 0.74 (95% CI=0.66-0.82) in men. A lower incidence rate was observed for cancers of breast (meta-SIR=0.67, 95% CI=0.47-0.86), colorectum (meta-SIR=0.80, 95% CI=0.61-0.99), and lung (meta-SIR=0.68, 95% CI=0.43-0.92) in women and for cancers of bladder (meta-SIR=0.54, 95% CI=0.39-0.68), larynx (meta-SIR=0.49, 95% CI=0.41-0.57), lung (meta-SIR=0.54, 95% CI=0.41-0.68), oesophagus (meta-SIR=0.62, 95% CI=0.44-0.81), and pancreas (meta-SIR=0.73, 95% CI=0.65-0.81) in men as compared to the general population. Non-significantly increased meta-SIRs were found for melanoma in women (meta-SIR=1.19, 95% CI=0.67-1.72) and non-Hodgkin lymphoma in men (meta-SIR=1.19, 95% CI=0.78-1.60). Conclusions. The overall cancer incidence rate was lower in AGRICOH than in the general population. The observed lower cancer incidence may be due to healthy worker bias, lower prevalence of risk factors, such as smoking in the agricultural populations, or other reasons. Further analysis is underway to explore any heterogeneity in SIR of cancer across cohorts.