Increased risk of second primary hematologic and solid malignancies in patients with mycosis fungoides: A Surveillance, Epidemiology, and End Results analysis.

BACKGROUND

Mycosis fungoides (MF) is associated with increased risk of second primary hematologic malignancies, but its association with second primary solid tumors is less well characterized.

OBJECTIVE

This retrospective analysis seeks to assess the risk of being diagnosed with a second primary hematologic or solid malignancy in patients with MF.

DESIGN

We performed an analysis of patients diagnosed with MF from 2000 through 2015 in the United States cancer registries of SEER-18 (N = 6742).

RESULTS

Relative risks were estimated by using standardized incidence ratios (SIRs). Among 6742 patients, there were 511 (7.5%) second cancer events (SIR, 10.15; 95% confidence interval [CI], 9.29-11.07). These included 184 (36.0%) hematologic malignancies (SIR, 39.71; 95% CI, 34.05-46.05) and 327 (64.0%) solid tumor malignancies (SIR, 7.33; 95% CI, 6.56-8.17). Patients with MF were at increased risk for non-Hodgkin lymphoma; Hodgkin lymphoma; melanoma; and lung, female breast, prostate, colon, and renal cancers. Females were at higher risk than males (P < .05). All ethnic groups showed a statistically significant elevation in SIRs. Elevation of SIRs was observed across all stages of MF.

CONCLUSIONS AND RELEVANCE: Patients with MF are at increased risk for diagnosis of second primary malignancies and should be carefully screened for discernable signs and symptoms of second malignancies.