Background: Sézary syndrome (SS) is characterized by a malignant proliferation of CD4+ve T cells, which may result in a degree of immunoparesis. Immunosuppression is associated with an increased incidence of internal malignant neoplasms and a high rate of nonmelanoma skin cancer, particularly squamous cell carcinoma. Therefore, we reviewed the incidence of secondary malignant neoplasms in patients with SS.
Observations: Of 71 patients with SS, 16 (23%) developed 19 secondary and tertiary malignant neoplasms. These malignant neoplasms included 8 cutaneous squamous cell carcinomas, 2 squamous cell carcinomas of the oral mucosa, and 9 other internal malignant neoplasms. The incidence of internal malignant neoplasms was twice that reported in patients of similar age treated for Hodgkin disease (P = .02). Furthermore, the incidence of cutaneous squamous cell carcinoma in the cohort was 42 times that observed in a study conducted in England of an age-matched population (1657 per 1 x 10(5) vs 39 per 1 x 10(5) person-years [95% confidence interval, 626-2856]).
Conclusions: A number of therapeutic modalities for SS are known to be carcinogenic. We compared the different therapeutic modalities received by our patients and found no significant difference between the total cohort of patients with SS and the patients who developed secondary malignant neoplasms. These data indicate that the high incidence of secondary malignant neoplasms in patients with SS is due, at least in part, to the disease itself. The clonal proliferation of CD4+ve T cells and the relative lymphopenia (compared with a healthy population) of nonneoplastic T cells may result in compromised immunosurveillance, so that early neoplasia, whether arising spontaneously or as a result of therapy, are not dealt with appropriately.