We examined associations of PIK3CA oncogene mutation with relapse , survival , and treatment efficacy in 627 stage III colon carcinoma case subjects within a randomized adjuvant chemotherapy trial ( 5-fluorouracil and leucovorin [ FU/LV ] vs irinotecan [ CPT11 ] , fluorouracil and leucovorin [ IFL ] ; Cancer and Leukemia Group B 89803 [ Alliance ] ) .