Abstract A52: Incidence of multiple primary cancers among Chinese survivors of nasopharyngeal carcinom

Nasopharyngeal carcinoma (NPC) is rare in most of the world but is very common in Chinese and other Southeast Asian populations including those now living in the U.S. and other western countries. Since NPC tends to strike in middle age and survival is quite good the problems of survivors, including second cancers are important. Previous studies of second primary tumors (SPTs) among NPC survivors have given conflicting results. In this study we examine incidence of SPTs among Chinese NPC survivors in Hong Kong and the United States. Medical records were reviewed for 1500 NPC patients from Hong Kong and data were collected on incidence of cancers after the index NPC case. Data on 996 Chinese-American patients were obtained from the U.S. National Cancer Institutes Surveillance, Epidemiology and End Results program database. Standardized incidence ratios (SIR) and 95% confidence intervals were estimated for cancer overall and cancers of common sites. In Hong Kong a statistically significant excess risk of cancer overall was found with females having greater excess risk than males and those diagnosed with NPC before age 40 had a higher excess risk than those whose NPC diagnosis occurred after age 40. Particularly strong significant excesses were noted for cancers of the tongue, brain, and nasal cavity. Among Chinese-Americans a significant excess risk was noted for lung cancer and cancers of the oral cavity and pharynx. Female NPC survivors also had a higher excess SPT risk than males among Chinese-Americans. Chinese NPC survivors appear to have an excess risk of some types of SPTs. Results are mostly consistent with a hypothesis that the excess is due to treatment for the original NPC. Physicians treating NPC patients should be aware of the risk of SPTs when they planning patient follow-up.