To assess risks for developing second malignancies in patients with mycosis fungoides or Sézary syndrome.
Retrospective study of 2 cohorts.
Nine population-based US cancer registries that constitute the Surveillance, Epidemiology, and End Results Program (SEER-9), and Stanford University referral center cohort of patients with cutaneous lymphoma.
Patients with mycosis fungoides or Sézary syndrome from the SEER-9 registry diagnosed and followed up from 1984 through 2001 and from the Stanford University cohort diagnosed and followed up from 1973 through 2001.
Main Outcome Measures
Relative risk was estimated using the standardized incidence ratio (SIR). The expected cancer incidence for both cohorts was calculated using age-, sex-, race-, and calendar year–specific SEER-9 incidence rates for the general population. Nonmelanoma skin cancers were excluded because these cancers are not routinely reported by the SEER database.
In the SEER-9 cohort (n = 1798), there were 197 second instances of cancer (SIR = 1.32; 95% confidence interval [CI], 1.15-1.52) at all sites. Significantly elevated risk (P<.01) was observed for Hodgkin disease (6 cases; SIR = 17.14; 95% CI, 6.25-37.26) and non-Hodgkin lymphoma (27 cases; SIR = 5.08; 95% CI, 3.34-7.38). Elevated risk (P<.05) was also observed for melanoma (10 cases; SIR = 2.60; 95% CI, 1.25-4.79), and urinary cancer (21 cases; SIR = 1.74; 95% CI, 1.08-2.66). In the Stanford University cohort (n = 429), there were 37 second instances of cancer (SIR = 1.04; 95% CI, 0.76-1.44). Elevated risk (P<.01) was observed for Hodgkin disease (3 cases; SIR = 27.27; 95% CI, 5.35-77.54). Elevated risk (P<.05) was also observed for biliary cancer (2 cases; SIR = 11.76; 95% CI, 1.51-42.02).
Updated SEER (population based) and Stanford (clinic based) data confirm the generalizability of earlier findings of increased risk of lymphoma in patients with mycosis fungoides or Sézary syndrome.