Salmonella or Campylobacter gastroenteritis prior to a cancer diagnosis does not aggravate the prognosis: a population-based follow-up study.

We hypothesized that preceding zoonotic Salmonella or Campylobacter gastroenteritis aggravated the prognosis in cancer patients. Exposed patients comprised all of those diagnosed with first-time Salmonella/Campylobacter gastroenteritis from 1991 and with first-time cancer diagnosis thereafter (through 2003) in two Danish counties. These patients were matched for main cancer type, gender, age and calendar period to unexposed cancer patients, i.e. those without Salmonella/Campylobacter gastroenteritis. We compared cancer stage by age- and comorbidity-adjusted logistic regression analysis, survival by comorbidity-adjusted Cox's regression analysis and mortality dependent on the time period between Salmonella/Campylobacter gastroenteritis and cancer by spline regression curves. The study cohort comprised 272 Salmonella/Campylobacter-exposed cancer patients and 2681 unexposed cancer patients. Prevalence odds ratios [95% confidence intervals (CI)] in exposed as compared with unexposed patients were 0.96 (0.74-1.25) for localized tumours, 1.15 (0.87-1.54) for regional spread and 1.14 (0.84-1.55) for metastases. Adjusted mortality rate ratios (95% CI) were 0.93 (0.75-1.16) for 0-1 year, 1.08 (0.84-1.39) for 2-5 years and 1.02 (0.60-1.73) for the remaining period. Mortality estimates did not change in relation to the time period between gastroenteritis and cancer. Salmonella/Campylobacter gastroenteritis prior to cancer was associated with neither the cancer stage nor a poorer prognosis.