Outcomes After Anticancer Treatment
Several studies evaluated the use of zinc monotherapy or in combination with vitamins and outcomes after anticancer treatment and demonstrated improvement in recurrence and survival in some populations.
Megadose vitamins, including vitamins A, C, E, B6, and zinc (90 mg) reduced the recurrence of bladder cancer compared with the same vitamins taken at the recommended daily allowance (RDA) level in a double-blind clinical trial.9 The 5-year estimates of tumor recurrence were 41% and 91% among patients who received the megadose and RDA vitamins, respectively (P = .0014).
The Linxian General Population Trial evaluated the effect of supplementation of 29,584 healthy adults from China for 5.25 years with 4 different combinations: retinol and zinc; riboflavin and niacin; vitamin C and molybdenum; β-carotene, vitamin E, and selenium. There was no significant difference in lung cancer–related death rates during the trial and 10 years after the study ended.10
Supplementation with the retinol and zinc combination, however, significantly reduced liver cancer mortality among patients aged younger than 55 (HR, 0.59; 95% CI, 0.34-1.00), but not among older patients.11
A randomized, double-blind, placebo-controlled trial demonstrated that zinc supplementation trended toward an improvement in 3-year local-free survival (LFS) compared with placebo (P = .092), particularly among patients with stage III to IV disease (P = .003), but there was no effect on 3-year overall survival (OS), disease-free survival (DFS), or metastases-free survival.12
A cohort of patients with nasopharyngeal carcinoma from this study, however, demonstrated significantly prolonged 5-year OS (P = .044), LFS (P =. 007), and DFS rates (P = .033) with zinc supplementation compared with placebo.13