Sir,

We read with great interest the article by RC Gerringet al1 regarding prognostic factors and survival rates in a retrospective case series of patients who underwent orbital exenteration for non-melanoma skin cancers (NMSC). The authors have thoroughly described the correlation between survival rates and some factors which are thought to influence the prognosis after orbital exenteration.

Their article does not make any reference to the important relation between immunosuppression and the behaviour of NMSC. There is a good deal of evidence that shows that azathioprine and cyclosporin, as well as other agents, adversely affect such cancers.2, 3 A direct carcinogenic effect has been described in transplant patients for both azathioprine and cyclosporin, beside their primary immunosuppressive role. The former acts as mutagen and photosensitizer by increasing the level of its metabolite 6-thioguanine, while the latter seems to upregulate the transforming growth factor β (TGF-β), a cytokine implicated in cells proliferation and transformation.

Immunological cancer surveillance systems in patients using these drugs in the long term are known to be impaired in the detection and eradication of precancerous lesions. Finally, evidences suggest that also immunosuppression related to HIV/AIDS, non-Hodgkin lymphoma and chronic lymphocytic leukaemia may increase the risk of developing more aggressive SCCs.4, 5

Even assuming that no immunosuppressed individuals were present in Gerring et al's1 sample, we believe that considering immunosuppression among the potential prognostic factors is mandatory as far as NMSC are concerned. This is extensively outlined in many studies, including major reviews and meta-analysis.