Risk of multiple primary cancers following melanoma and non-melanoma skin cancer.

BACKGROUND

The relationship between cutaneous malignancies and successive primary cancers has been studied since several years, but it still remains controversial.

OBJECTIVE

The aim of this study was to evaluate the excess risk of multiple primary cancer among the population of Umbria, Italy, that survived a skin cancer.

METHODS

The data registered in the Umbrian Population Cancer Registry from 1994 to 2006 were collected, recorded, and analysed in accordance to the standard methods recommended for cancer registries. Among skin cancer patients, those with multiple cutaneous and non-cutaneous cancers were selected. Only sites with a frequency of more than five cases were considered. The expected number of cases was obtained from indirect standardization with regional incidence rates in several sites that incurred in the overall period. The significance of the observed/expected ratios and the corresponding 95% CI were based on the Poisson distribution.

RESULTS

In men, a significant standardized incidence ratio (SIR) was found for melanoma (2.21), non-melanoma skin cancers (1.86), Hodgkin's (4.95) and non-Hodgkin lymphoma (1.82), and tongue/mouth cancer (2.47). In women, melanoma, non-melanoma skin and breast cancer showed a significant high SIRs (4.13, 1.55 and 1.28 respectively). All other cancers showed a non-significant SIR. Considering all sites combined and all sites except skin cancers, the analysis showed a significant excess in men, whereas a significant risk was observed in women only when also skin cancers were considered.

CONCLUSIONS

Data from the whole of Umbrian population revealed that skin cancer patients experience marked excess risk of further primary cancers. The main risk in both genders is skin melanoma and other skin cancers. The excess of lymphomas and tongue/mouth cancers is also significant in men, and breast cancer in women. These observations prompt us to include a screening for these cancers in the follow-up of our patients surviving a skin malignancy.