Gestational trophoblastic neoplasia in American Indians

OBJECTIVE: To analyze gestational trophoblastic neoplasia (GTN) trends among American Indians (AI) using population-based data. STUDY DESIGN: GTN incidence, by race and age, was calculated using data collected by the New Mexico Tumor Registry over 29 years (1973-2001). Live birth, pregnancy and women at risk were tabulated using data derived from the state's vital record annual reports and from the registry. Statistical methods included trends analysis and Poisson regression. There is no national registry in the United States for all GTN. Therefore, the Surveillance, Epidemiology and End Results (SEER) database was used to identify choriocarcinoma cases in American Indians between 1973 and 1999. RESULTS: Within New Mexico, 1,082 cases of GTN were identified among 752,374 live births and 904,831 pregnancies, with ratios of 1:695 and 1:836, respectively, affecting 234 AI, 355 non-Hispanic whites (NHW), 463 Hispanic whites (HW) and 30 other nonwhites. Ratios per live births (pregnancy), respectively, were significantly higher in AI (AI 1:439 [1:487], NHW 1:739 [1:949], HW 1:783 [1:903]), as was age-adjusted incidence per 100,000 woman-years (AI 10.62, NHW 3.53, HW 5.15, all P<.0001). Using Poisson models with live birth and woman-year denominators, AI were found to be at increased risk for all GTN histologic subsets (complete, partial and invasive hydatidiform mole and choriocarcinoma). Of 524 total gestational choriocarcinoma cases identified within SEER, 8 (1.8%) affected American Indians; of them, 7 were from New Mexico. CONCLUSION: In New Mexico, AI continue to be at higher risk of GTN than are other groups. Given the rarity of choriocarcinoma within SEER, especially among AI, the New Mexico dataset provides the best available estimate of trends in U.S. AI GTN risk.