Taking a daily multivitamin didn’t improve survival or reduce the risk that colon cancer would come back for stage III patients enrolled in a clinical trial of chemotherapy after surgery.
Although about half of patients in the trial took a multivitamin supplement during their treatment, the vitamin didn’t improve their outcomes, nor did it reduce side effects. At the same time, multivitamin use didn’t have a detrimental effect.
Researchers asked about 1,000 patients at the end of their chemotherapy and then about 6 months later about whether they took multivitamins during their chemo or afterwards. Patients in the trial had randomly received one of two different chemos, and the trial showed no difference between the two treatments.
After about 7 years of follow-up there was no difference between patients who took multivitamins during chemotherapy and those who didn’t for cancer-free survival, recurrence, or overall survival. There was also no difference for patients who said that they took multivitamins in the months after they finished chemo.
However, multivitamins taken during chemotherapy did appear to benefit patients who were 60 years old or younger. who had about a 30 percent reduction in the risk of dying from cancer or having their colon cancer return. This difference didn’t seem to be related to family history or microsatellite instability. But taking multivitamins after chemotherapy was completed, didn’t improve outcomes for these younger patients.
Obese patients did derive benefit from multivitamin use, but those who were merely overweight actually did worse in terms of disease-free survival when they took them. In normal weight people, vitamins didn’t make a difference.
Commenting on the study, Charles Fuchs, MD, director of gastrointestinal oncology at Dana-Farber Cancer Institute and the paper’s senior author, said.
This study adds to a growing body of research that questions the purported benefit of multivitamin use, and it underscores the need to investigate the use of individual vitamins, such as vitamin D, which may, in fact, provide real benefit.
Dr. Fuchs noted that most multivitamins contain a small dose of vitamin D.
Use of multivitamins during chemotherapy didn’t appear to affect side effects, with no significant differences between those who took them and those who didn’t for nausea, vomiting, diarrhea, or lowered white cell counts. There was less severe fatigue in multivitamin users, with 10.8 percent of the nonusers experiencing grade 3 or 4 fatigue compared to 7.4 percent of those who took vitamins.
Lead author Kimmie Ng and her colleagues concluded,
Multivitamin use during and after adjuvant chemotherapy was not significantly associated with
improved outcomes in patients with stage III colon cancer.