A new study suggests that it could be risky to take supplements during chemotherapy for mesothelioma and other cancers.
The study took place at the Roswell Park Comprehensive Cancer Center in Buffalo, New York. It focused on more than 1,100 breast cancer patients. It found that patients who took certain antioxidant supplements during chemotherapy had worse outcomes than those who did not.
The study’s authors say antioxidants undermine one of the main jobs of chemotherapy drugs – to create oxidative stress in cancer cells. Chemotherapy is the primary first-line treatment for malignant mesothelioma and many other cancers.
Why Avoid Antioxidant Supplements During Chemotherapy?
Antioxidants are compounds found in many fruits and vegetables. Vitamins A, C, E, and B12 are examples of antioxidants.
Injury, disease, and even ordinary metabolism cause oxidative stress. Oxidative stress creates “free radicals” that can damage healthy cells. Antioxidants help fight the damage by mopping up free radicals.
Many people take antioxidant supplements to make up for the lack of fruits and vegetables in their diet. On the surface, taking supplements during chemotherapy may sound like a good idea for mesothelioma patients, too. This is especially true if treatment has suppressed their appetite and they are not eating a healthy diet.
But chemotherapy is supposed to create free radicals to damage mesothelioma cells. Unfortunately, antioxidant supplements during chemotherapy may protect mesothelioma cells the same way they protect healthy cells.
The Case Against Antioxidants for Mesothelioma Patients
Doctors thought that dietary supplements during chemotherapy might hinder treatment. But until the latest study, they did not have much evidence to back up the idea.
The trial was an arm of a larger study aimed at determining the best dose and schedule for chemotherapy drugs. More than 1,100 breast cancer patients answered surveys on their use of vitamins. Researchers followed the womens’ progress for six years.
They found that women who took certain antioxidant supplements during chemotherapy or before it probably did more harm than good. These patients were 41 percent more likely to experience recurrence of their cancer. They were also 40 percent more likely to die during the follow-up period.
The results suggest that Vitamin B12 may be of special concern to mesothelioma patients and others with cancer. Patients on B12 were 83 percent more likely to have recurrence and 22 percent more likely to die than those who did not take supplements.
Previous research in lung cancer patients produced similar results. Last year, researchers in Sweden and New York showed how antioxidants may stimulate the spread of mesothelioma and lung cancer.
The authors of the new study recommend caution for cancer patients considering supplements during chemotherapy. They do say that a basic multivitamin is OK.
Ambrosone, C, et al, “Dietary Supplement Use During Chemotherapy and Survival Outcomes of Patients With Breast Cancer Enrolled in a Cooperative Group Clinical Trial (SWOG S0221)”, December 19, 2019, https://ascopubs.org/doi/full/10.1200/JCO.19.01203
Wiel, C, et al, “BACH1 Stabilization by Antioxidants Stimulates Lung Cancer Metastasis”, June 27, 2019, Cell, https://doi.org/10.1016/j.cell.2019.06.005