Introduction Successive job changes may reflect precarious employment, job dissatisfaction or promotions, all of which can result in accrued stress, disrupted social connections and health-altering circumstances and behaviours. Evidence is lacking on the potential role of job stability in cancer development.

Objectives We investigated the association between the number of jobs held and jobs duration over the career, and the risk of prostate cancer, overall and by cancer aggressiveness.

Methods Data from the Prostate Cancer & Environment Study, a population-based case-control study conducted in 2005–2012 in Montreal, Canada were used. Incident cases (n=1,931), aged < 76 years, were ascertained across hospitals in the Montreal area. Population controls (n=1,994) from the same area, frequency-matched to cases by age (±5 years), were identified from the electoral list. Information on the number of paid jobs held for ≥ 1 year throughout the career and the duration of each job was elicited during face-to-face interviews. Unconditional logistic regression was used to assess odds ratios (OR) and 95% confidence intervals (CI), adjusting for age, ancestry and education.

Results Subjects had held 5 jobs, on average (± 3), with a mean job duration of 11.1 years (± 7.9). A greater number of jobs held was associated with a higher risk of prostate cancer. The OR for men who had had > 6 jobs was 1.23 (95% CI = 1.04–1.46), compared to men who had held 1–3 jobs, with no differences according to cancer aggressiveness. Conversely, men who had held shorter jobs, on average, had a higher risk of prostate cancer, following a dose-response pattern (p-trend 0.047). The association was more pronounced for non-aggressive tumours.

Conclusion Our results suggest that job stability throughout the career may have a protective effect against prostate cancer. Further in-depth analyses are warranted. These findings are novel and require replication.