Multivitamins help improve colorectal cancer survival

Patients who take multivitamin supplements at a moderate dose following their diagnosis of nonmetastatic colorectal cancer (CRC) appear to have a lower mortality, reports a recent study.

Use of multivitamin supplements has been associated with a reduced CRC risk, but its influence on survival has remained unknown, according to the researchers, led by Ming-Ming He from Harvard University T.H. Chan School of Public Health in Massachusetts, US, and Sun Yat-sen University Cancer Center in Guangdong, China.

Co-author Mingyang Song, from Harvard University T.H. Chan School of Public Health and Massachusetts General Hospital in the US, presented the study at the Digestive Disease Week (DDW) 2022.

He, Song, and their team examined the use and dose of multivitamin supplements with repeated questionnaires among 2,424 patients diagnosed with stages I to III CRC in two prospective cohort studies. Cox regression was used to calculate the multivariable hazard ratios (HRs) and 95 percent confidence intervals (CIs) of all-cause and CRC-specific mortality according to postdiagnostic use and dose of multivitamin supplements.

In addition, the researchers assessed the dose-response relationship using the restricted cubic spline analysis and investigated the joint association of pre- and postdiagnostic multivitamin use.

A total of 1,512 deaths occurred during a median follow-up of 11 years. Of these, 343 were due to CRC. Patients who used multivitamins at a dose of 3‒5 tablets/week after diagnosis had a lower CRC-specific mortality (HR, 0.55, 95 percent CI, 0.36‒0.83; p=0.005), while users at doses of 3‒5 and 6‒9 tablets/week following diagnosis had a lower all-cause mortality (HR, 0.81, 95 percent CI, 0.67‒0.99; p=0.04 and HR, 0.79, 95 percent CI, 0.70‒0.88; p<0.001, respectively) relative to nonusers. [DDW 2022, abstract Tu1417]

In dose-response analysis, He and colleagues observed a curvilinear relationship for both CRC-specific and all-cause mortality, with the maximum risk reduction seen at 3‒5 tablets/week and no further decrease at higher doses (p<0.001 and p=0.004 for nonlinearity, respectively).

The researchers also compared new users after CRC diagnosis to nonusers in both the pre- and postdiagnosis periods and found that use of multivitamin supplements at a dose of <10 tablets/week resulted in a lower all-cause mortality (HR, 0.81, 95 percent CI, 0.71‒0.94; p=0.005); on the other hand, use at a dose of ≥10 tablets/week (HR, 1.58, 95 percent CI, 1.07‒2.33) and discontinued use (HR, 1.35, 95 percent CI, 1.14‒1.59) led to an increased mortality risk.

“The findings need to be confirmed in randomized controlled trials,” said the researchers.

In an earlier study by Kimmie Ng and colleagues, results showed no significant association between multivitamin use during and after adjuvant chemotherapy and improved outcomes in patients with stage III colon cancer. [J Clin Oncol 2010;28:4354-4363]

Furthermore, neither an increasing number of tablets nor increasing duration of use before cancer diagnosis correlated with cancer recurrence or mortality. Use of multivitamins also failed to improve the rates of grade 3 and higher gastrointestinal toxicity.

On the other hand, a 2019 study by Wanshui Yang and colleagues found that higher calcium intake after diagnosis could lower the risk of death among CRC patients. [Clin Cancer Res 2019;25:1980-1988]

“[W]e observed that higher postdiagnostic calcium intake, including from supplement use, might be associated with lower risk of death among CRC patients,” Yang said. “Our findings need to be confirmed by further studies, including possible clinical trials of calcium supplementation in patients with nonmetastatic CRC.”