Psoriasis vulgaris and familial cancer risk- a population-based study.

Background: Follow-up studies of psoriasis patients indicate an increased risk in the occurrence of malignancies at different sites of origin. Population stratification and/or complicated interpretation of evidence on the risk of cancer (due to the small number of patients included in most series) lead to inconsistent data. Herein we investigated the risk of occurrence of malignancies at different sites of origin in a series of 517 psoriasis patients and their 1st degree relatives.

Methods: We evaluated the tumour spectrum as well as the age of the patient at diagnosis of cancers in psoriasis families along with the observed and expected frequencies of malignancies. The distribution of 17 common mutations/polymorphisms in 10 known cancer susceptibility genes among psoriasis patients and 517 matched healthy controls were examined. No such study has been published to date.

Results: The statistical comparison of the observed and expected frequencies of cancers revealed a higher than expected occurrence of Hodgkin's lymphoma among males in psoriasis families when compared to the general population (OR=1.8, 95%CI 1.6-2.1, p=0.002). There was a non-significant tendency towards a younger age of onset and overrepresentation of laryngeal cancer and leukaemia in psoriasis families. We found no major differences in the distribution of cancer susceptibility mutations among our cases and the healthy controls.

Conclusions: The results of our study suggest an increased risk of Hodgkin's lymphoma for male members of psoriasis families. Further studies are needed to confirm the findings and to evaluate whether or not the application of cancer surveillance protocols for Hodgkin's lymphoma, leukaemia and laryngeal cancer are justified in these families.