Occupational variation in the incidence of lip cancer in the Nordic countries

Introduction: While certain occupations, such as agriculture and fishery, have been associated with an increased risk of lip cancer, the occupational risk profile of lip cancer and its change over time remain poorly known. This study aims to evaluate the incidence of lip cancer across different occupations in the Nordic countries. Methods: The Nordic Occupational Cancer Study (NOCCA) covers 14.9 million people and includes 45 years of cancer incidence data, from 1961 to 2005, linked to occupational categories for all the five Nordic populations. Standardized incidence ratios (SIRs) with 95% confidence intervals (CIs) were used to quantify the risk of lip cancer across occupational categories relative to the entire national populations. Results: There were a total of 14,477 male and 3008 female lip cancer patients identified during follow up. The highest SIRs were observed among male fishermen (SIR 2.26, 95% CI: 2.04–2.50), gardeners (SIR 1.60, 95% CI: 1.48–1.72), and farmers (SIR 1.60, 95% CI: 1.55–1.66). A significantly reduced risk of lip cancer (SIR < 0.50) was observed among male physicians, teachers, religious workers, artistic workers, journalists, administrators, printers, waiters, and hairdressers. Among women, no occupations were associated with an increased risk of lip cancer. Conclusions: The incidence of lip cancer varies widely between outdoor and indoor occupations. Occupations involving outdoor activity and exposure to sunlight show the most elevated SIRs.