Increased Risk of Second Malignancies In Young Patients with Mycosis Fungoides Diagnosed Before 30 Years of Age: A Population-Based Study

It has been reported that adults with mycosis fungoides have an increased risk of developing second malignancies. Although children and young adults with mycosis fungoides appear to have a higher proportion of early-stage disease and a more favorable outcome than adults, the risk of second malignancies in this population is not known.

A total of 178 patients diagnosed with mycosis fungoides or Sézary syndrome (MF/SS) before 30 years of age were identified from nine Surveillance, Epidemiology, and End Results (SEER) cancer registries in the U.S. from 1973 to 2007. The risk of second malignancies was assessed by calculating the standard incidence ratio (SIR), which compares the observed cancer incidence in the MF/SS cohort with the expected incidence in the age-, sex-, race-matched general population. Overall survival was calculated among 166 patients diagnosed with MF/SS before age 30 years, identified from the California Cancer Registry between 1988 and 2007.

In the MF/SS cohort from 1973 to 2007, 8 second cancers at all sites were reported in 7 patients, among which 5 cases were Hodgkin's and Non-Hodgkin's lymphomas. The SIR for a secondary malignancy at any site was 3.60 (95% confidence interval [CI]=1.55-7.10). Significantly increased risks of lymphoma and melanoma were observed, with SIR=24.23 (95% CI=7.87-56.55) and SIR=10.61 (95% CI=1.29-38.33), respectively. The median time to secondary malignancy was 2.9 years (range = 1.4 to 15.8 years). Among MF/SS patients diagnosed in California from 1988 to 2007, the 5- and 10-year overall survival was 96% (95% CI=91.4-98.5) and 92% (95% CI=86.1-96.5), respectively.

Patients with MF/SS diagnosed before 30 years of age have favorable overall survival. However, these patients appear to have an increased risk of developing secondary cancers, similar to what we have seen in the adult MF/SS patients. Additional multi-center studies on the long term outcome of this young patient population are warranted.

No relevant conflicts of interest to declare.