Analysis of second primary cancers in gastroinstestinal stromal tumor patients using SEER database.

Abstract

327 Background: Development of second primary cancers among gastrointestinal stromal tumor (GIST) patients is not very well studied. This study was conducted to evaluate second primary malignancies in GIST patients using U.S. Surveillance, Epidemiology, and End Results (SEER) cancer registry database. Methods: We analyzed the Surveillance, Epidemiology, and End Results (SEER Stat) database: Incidence - SEER 13 Regs Research Data, Nov 2011 Sub, Vintage 2009 Pops (1992-2009) using MP-SIR session. We analysed secondary cancer rate among adult GIST patients during the period 1992-2009. We also compared the risk of secondary malignancies in pre- (1992-2001) to post-imatinib (2002-2009) eras. We used SEER MP-SIR session and Graph pad scientific software to calculate p value. Results: There were 2,436 (693 in pre-imatinib era and 1,743 in post-imatinib era) GIST patients reported during 1992-2009 period in SEER database. Among them, 163 GIST patients developed second primary malignancy, which is significantly higher than expected in general population, with observed/expected (O/E) ratio: 1.31, p value = <0.05, (95% CI: 1.11-1.52) and excess risk of 39.76 per 10,000 population. The total number of second primary cancers in GIST in pre- and post-imatinib eras were 69 and 94, p value = <0.0001 with observed/expected (O/E) ratio of 29.18 and 48.22 respectively. The total number of second primary solid tumors in pre- and post-imatinib era was: 59 and 84, p value=0.0008 and O/E ratio: 20.18 vs 43.32 respectively. Conclusions: This study showed overall increased risk of second primary malignancies among GIST patients as compared to general population. There was significantly increased risk of second primary malignancies, especially solid tumors in post-imatinib era. [Table: see text]