GSTM1 and infection: Treating center, preoperative Hb, postoperative Hb, and treatment modality of the initial/primary tumor were significantly associated with overall postoperative complication rates (including PCF, postoperative bleeding, and infection) upon univariable analysis, with lower Hb levels (<12.5 g/dl) and chemoradiation (when compared to RT alone) increasing the probability for a complicated postoperative course.