Geographic variations and temporal trends in prostate cancer in Martinique over a 25-year period

BACKGROUND: In Martinique, prostate cancer incidence rates have been increasing since the 1980s and are actually among the highest worldwide. Exposure to lifestyle (changes in dietary habits), environmental factors (exposure to organochlorine pesticides) and modifications in diagnostic and screening procedures, are favored etiological hypotheses. The aim of the present study is to describe and interpret prostate cancer incidence trends over the past 25 years (1981–2005) in Martinique. METHODS: Data on incident prostate cancer cases from 1981 to 2005 were obtained from the population-based Martinique Cancer Registry. World age-standardised incidence rates were calculated and an age-period-cohort model was used to determine average annual variations for prostate cancer during the study period. Age and period effects were assessed, employing the method proposed by Clayton and Schifflers. Relative changes in prostate cancer incidence, at five-year intervals between 1981 and 2005, were also studied with an organochlorine pesticide exposure index, built as a proxy of the relative intensity of chlordecone use on the island between 1973 and 1993. RESULTS: Prostate cancer incidence was found to increase by 5.07% annually between 1981 and 2005. Compared to 1981–1985, prostate cancer relative risk, in men aged 50–74 years and 75 years and above was respectively 5.98% and 3.07% from 2001 to 2005. An inverse association between population pesticide exposure levels and prostate cancer risk was also highlighted, with highest prostate cancer incidences observed in urban zones showing the lowest soil contamination levels by the chlordecone pesticide (zone 1). CONCLUSION: No conclusive association was found between the intensity of pesticide use and the subsequent rise in prostate cancer incidence. However, it remains necessary to develop and reinforce continuous monitoring of prostate cancer incidence and mortality trends on the island. Further studies are also needed in order to consider other risk factors such as modifications in diagnostic and screening procedures over the last 25 years.