Grant: Operating Grant

The incidence of cutaneous malignant melanoma(CMM);the least common but the most fatal form of skin cancer; is continuing to rise in Canada and other Western countries. The only environmental factor known to increase the risk of developing CMM is sun exposure. Although the great majority of the more than 30 past studies have shown a positive relationship between sun exposure and CMM, the elevated risk in those most exposed tends to be modest. This has spurred recent attempts to see if other environmental exposures may also increase melanoma risk. Recently we examined the relationship between blood levels of organochlorine compounds (PCBs and chlorine-based pesticides)and risk of melanoma in a small group of melanoma patients and healthy controls. After adjusting for sun sensitivity and sunlight exposure (known risk fators for melanoma) we found strong relationships between blood levels of several PCBs and risk of CMM. However, this study was of a preliminary nature with relatively small numbers of patients, and thus the findings need to be confirmed in a larger study. We propose to enroll 400 melanoma patients and 400 healthy controls to see if results confirm those seen in the original study. We will collect information on variables such as skin and hair colour, skin sensitivity to sunlight, and history of sun exposure. In addition we will collect a blood sample from each participant. Plasma from the blood sample will be assayed for residues of 14 PCB types (congeners)and 11 pesticides. Multivariate statistical techniques will then be used to evaluate whether results confirm a relationship between organochlorine levels and melanoma after control for pigmentation, sun sensitivity and sun exposure. Findings from our study could provide new leads for prevention of melanoma and help reverse the rising incidence of melanoma in the Canadian population.