Cancer Therapy: Clinical Nitric Oxide Synthase Variants and Disease-Free Survival among Treated and Untreated Breast Cancer Patients in a Southwest Oncology Group Clinical Trial

Purpose: Numerous chemotherapeutic agents are cytotoxic through generation of reactive species, and variability in genes related to oxidative stress may influence disease-free survival (DFS). We examined relationships between DFS and variants in NOS3, as well as NQO1, NQO2, and CBR3, among treated and untreated breast cancer patients in a Southwest Oncology Group clinical trial (S8897). Experimental Design: In the parent trial, women were assigned according to prognostic features; the high-risk group was randomized to cyclophosphamide, i.v. methotrexate, and 5-fluorouracil or to cyclophosphamide, i.v. doxorubicin, and 5-fluorouracil ± tamoxifen, and the low-risk group did not receive adjuvant therapy. We extracted DNA from normal lymph node tissue and examined functional polymorphisms in NOS3, NQO1, NQO2, and CBR3, in relation to DFS, using Cox proportional hazard model. Results: There were significant interactions between DFS, adjuvant therapy, and NOS3 Glu298Asp and -786 polymorphisms, alone and in combination (P for interaction = 0.008). When NOS3 genotypes were combined, women with genotypes encoding for lower nitric oxide who received chemotherapy had a >2-fold increase in hazard of progression (hazard ratio, 2.32; 95% confidence interval, 1.26-4.25), whereas there was reduced risk for those who did not receive adjuvant therapy (hazard ratio, 0.42; 95% confidence interval, 0.19-0.95). There were no associations between the other genotypes and DFS in either group. Conclusion: Variants encoding lower activity of NOS3 may affect outcomes in breast cancer patients, with the direction of risk differing depending on chemotherapy status. These results may mirror the known dual functions of nitric oxide and nitric oxide synthase, depending on oxidative environment. (Clin Cancer Res 2009;15(16):5258–66) Authors' Affiliations: DepartmentofCancerPreventionandControl,RoswellPark Cancer Institute; Department of Pharmaceutical Sciences, The State University of New York at Buffalo, Buffalo, New York; PharmacoGenomics Research Center, Inje University College of Medicine, Busan, Korea; Southwest Oncology Group Statistical Center, Seattle,Washington; Division of Hematology/Oncology, Cardinal Bernardin Cancer Center, Loyola University Stritch School of Medicine,Maywood, Illinois; Clinical Trials Office, University of Arizona Cancer Center, Tucson, Arizona; Breast Oncology Program, 6312 CCGC, University of Michigan Medical Center, Ann Arbor, Michigan; Department of Pathology, University of Texas Health Science Center at San Antonio, San Antonio, Texas; University of Arkansas for Medical Sciences, LittleRock,Arkansas; TheAngelesClinic andResearch Institute, Santa Monica, California; Heartland Cancer Research CCOP, Missouri Baptist Medical Center, St. Louis,Missouri; DepartmentofMolecular andCellularBiology, Baylor College ofMedicine, Houston, Texas; and Sidney Kimmel Comprehensive CancerCenter at JohnsHopkins,Baltimore,Maryland Received 3/19/09; revised 5/12/09; accepted 5/13/09; published OnlineFirst