1. Polymorphisms in folate-metabolizing enzymes and response to 5-fluorouracil among patients with stage II or III rectal cancer (INT-0144; SWOG 9304).
- Author
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Ulrich CM, Rankin C, Toriola AT, Makar KW, Altug-Teber Ö, Benedetti JK, Holmes RS, Smalley SR, Blanke CD, and Lenz HJ
- Subjects
- Adult, Aged, Aged, 80 and over, Disease-Free Survival, Female, Folic Acid, Genetic Association Studies, Glycine Hydroxymethyltransferase genetics, Humans, Male, Middle Aged, Pharmacogenetics, Polymorphism, Single Nucleotide, Rectal Neoplasms pathology, Reduced Folate Carrier Protein genetics, Thymidylate Synthase genetics, Fluorouracil administration & dosage, Genetic Predisposition to Disease, Methylenetetrahydrofolate Reductase (NADPH2) genetics, Rectal Neoplasms genetics
- Abstract
Background: Recurrence and toxicity occur commonly among patients with rectal cancer who are treated with 5-fluorouracil (5-FU). The authors hypothesized that genetic variation in folate-metabolizing genes could play a role in interindividual variability. The objective of the current study was to evaluate the associations between genetic variants in folate-metabolizing genes and clinical outcomes among patients with rectal cancer treated with 5-FU., Methods: The authors investigated 8 functionally significant polymorphisms in 6 genes (methylenetetrahydrofolate reductase [MTHFR] [C677T, A1298C], SLC19A1 [G80A], SHMT1 [C1420T], dihydrofolate reductase [DHFR] [Del19bp], TS 1494del,and TSER) involved in folate metabolism in 745 patients with TNM stage II or III rectal cancer enrolled in a phase 3 adjuvant clinical trial of 3 regimens of 5-FU and radiotherapy (INT-0144 and SWOG 9304)., Results: There were no statistically significant associations noted between polymorphisms in any of the genes and overall survival, disease-free survival (DFS), and toxicity in the overall analyses. Nevertheless, there was a trend toward worse DFS among patients with the variant allele of MTHFR C677T compared with wild-type, particularly in treatment arm 2, in which patients with the MTHFR C677T TT genotype had worse overall survival (hazards ratio, 1.76; 95% confidence interval, 1.06-2.93 [P = .03]) and DFS (hazards ratio, 1.84; 95% confidence interval, 1.12-3.03 [P = .02]) compared with those with homozygous wild-type. In addition, there was a trend toward reduced hematological toxicity among patients with variants of SLC19A1 G80A in treatment arm 1 (P for trend, .06) and reduced esophagitis/stomatitis noted among patients with variants of TSER in treatment arm 3 (P for trend, .06)., Conclusions: Genetic variability in folate-metabolizing enzymes was found to be associated only to a limited degree with clinical outcomes among patients with rectal cancer treated with 5-FU., (© 2014 American Cancer Society.)
- Published
- 2014
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