Antioxidants May Increase Risk for Melanoma Metastasis

Source: Clinical Oncology News. November 2015

A mouse model indicates that some counterintuitive findings, namely, that the class of “antioxidant” supplements—often touted in the lay press for their chemoprotective quality—can actually increase the number of metastases in melanoma patients (Sci Transl Med 2015;7[308]:308re8, PMID: 26446958). Researchers found that administering N-acetylcysteine (NAC) in mice with melanoma doubled the number of lymph node metastases.

“Our finding of increased metastasis suggests that cancer patients should use antioxidant supplements with caution,” the authors emphasized.

Prior results have demonstrated that, in mice with BRAF– and KRAS-induced lung cancer, those given NAC and vitamin E experience increased proliferation of lung cancer cells and have larger tumors than those not given the substances (Sci Transl Med 2014;6[221]:221ra15, PMID: 24477002). To determine whether antioxidants have the same effect on melanoma behavior, researchers administered 1 g of NAC per liter of water (an amount that corresponds to between 665 and 1,330 mg/kg of NAC in humans weighing 70 kg) to mice with theBRAF allele.