Time dependence of critical deletions as prognostic factor for relapse-free survival (RFS) in localised GIST. A Spanish Group for Sarcoma Research (GEIS) study

Abstract

10508 Background: Deletions involving KIT Ty557-Lys558 were related with a statistically significant worse RFS in localized and completely resected GIST patients, as it was published with a median follow-up of 44 months (J Cin Oncol 23: 6190–6198, 2005). The prognostic significance of such critical mutations for RFS over time as well as its relationship with the more recent prognostic index is unknown. Methods: To evaluate the time dependence of prognostic factors for RFS, a series of 162 localized GIST patients has been updated. The relative risk for recurrence was analyzed univariately and multivariately for the various prognostic factors, using the Cox proportional hazards model, over the entire follow-up period and over the intervals 0–4 years and > 4 years. The factors assessed were as follows: tumor location, size, mitotic rate per 50 HPF, cellularity, mitotic rate and size risk categories (Fletcher risk, FRC), mitoses-size and location risk categories (Miettinen risk, MRC) (Semin Diagn Pathol 23: 7...