12/10/2005 (NewsRx.com) -- Antioxidant vitamins might prevent theincidence of second primary cancers in patients with head and neckcancers.
According to recent research from Canada, "Although low dietary intakes ofantioxidant vitamins and minerals have been associated with higher risksof cancer, results of trials testing antioxidant supplementation forcancer chemoprevention have been equivocal. We assessed whethersupplementation with antioxidant vitamins could reduce the incidence ofsecond primary cancers among patients with head and neck cancer."
"We conducted a multicenter, double-blind, placebo-controlled, randomizedchemoprevention trial among 540 patients with stage I or II head and neckcancer treated by radiation therapy between October 1, 1994, and June 6,2000," explained I. Bairati and colleagues, University of Laval.
"Supplementation with alpha-tocopherol (400 IU/day) and beta-carotene (30mg/day) or placebo began on the first day of radiation therapy andcontinued for 3 years after the end of radiation therapy. In the course ofthe trial, beta-carotene supplementation was discontinued after 156patients had enrolled because of ethical concerns. The remaining patientsreceived alpha-tocopherol or placebo only."
"Survival was evaluated by Kaplan-Meier analysis. Cox proportional hazardsmodels were used to estimate hazard ratios (HRs) and 95% confidenceintervals (CIs). All statistical tests were two-sided. After a medianfollow-up of 52 months, second primary cancers and recurrences of thefirst tumor were diagnosed in 113 and 119 participants, respectively,"reported the investigators.
"The effect of supplementation on the incidence of second primary cancersvaried over time. Compared with patients receiving placebo, patientsreceiving alpha-tocopherol supplements had a higher rate of second primarycancers during the supplementation period (HR=2.88, 95% CI=1.56 to 5.31)but a lower rate after supplementation was discontinued (HR=.41, 95%CI=.16 to 1.03). Similarly, the rate of having a recurrence or secondprimary cancer was higher during (HR=1.86, 95% CI=.1.27 to 2.72) but lowerafter (HR=.71, 95% CI=.33 to 1.53) supplementation with alpha-tocopherol."
The researchers concluded, "The proportion of participants free of secondprimary cancer overall after 8 years of follow-up was similar in botharms. alpha-tocopherol supplementation produced unexpected adverse effectson the occurrence of second primary cancers and on cancer-free survival."
Bairati and colleagues published their study in the Journal of theNational Cancer Institute (A randomized trial of antioxidant vitamins toprevent second primary cancers in head and neck cancer patients. J NatlCancer Inst, 2005;97(7):481-488).
For additional information, contact F. Meyer, University of Laval, CenterRech Cancerol, 11 Cote Palais, Quebec City, PQ G1R 2J6, Canada.
Publisher contact information for the Journal of the National CancerInstitute is: Oxford University Press Inc., Journals Dept., 2001 EvansRd., Cary, NC 27513, USA.
This article was prepared by Cancer Weekly editors from staff and otherreports.