Abstract
Purpose:
The long term survival in uveal melanoma (UM) patients is about 50% and these patients may be at higher risk of developing second primary cancers (SPC). In other malignancies, the risk of SPC has been linked with radiotherapy (RT). Despite this knowledge, no population-based studies have been done on UM survivors after radiation became standard of care. The aim of this study was to characterize the long-term SPC risk in subjects previously diagnosed with UM and to determine if RT is an independent risk factor.
Methods:
This is a retrospective cohort study. Using the Surveillance, Epidemiology and End Results (SEER) 9 database from the United States of America, we identified patients with a diagnosis of UM as their first malignancy between 1973 to 2011. The second cancer events were defined as those diagnosed at least two months after the UM. Poisson regression was used to model standardized incidence ratios (SIR) and excess absolute risks (EAR) of SPC, compared with a reference SEER population matched for sex, 5-year age group, race, site and calendar year. Multivariate Cox regression model was used to evaluate the effect of RT in SPC risk.
Results:
Of the 3,736 UM patients identified, 15.3% developed a SPC during a median follow-up of 139 months (range: 12-463 months). This represented a 10% higher risk compared to the general reference population, mainly due to a significantly increased risk of salivary gland tumors (SIR=4.27, p<0.05, EAR=1.22), skin melanomas (SIR=2.94, p<0.05, EAR=10.18) and kidney tumors (SIR=2.05, p<0.05, EAR=3.67). The occurrence of second UM was also increased (SIR=16.95, p<0.05, EAR=3.26), which may represent a recurrence of melanoma or true second primary malignancies. RT was performed in 38.3% of the patients. The multivariate analysis revealed that this treatment was not an independent risk factor for SPC (HR=1.27, 95%CI: 0.97-1.65, p=0.08), after adjusting for age at diagnosis, sex, race and surgical treatment.
Conclusions:
Uveal melanoma survivors presented a 10% higher risk of SPC as compared to the general population. RT does not seem to be an independent risk factor for second primary cancers.