The prognostic significance of supplementing co-enzyme Q(10) (CoQ(10)), riboflavin and niacin (CoRN) along with tamoxifen to breast cancer patients was evaluated by measuring the serum cytokine levels of interleukin (IL)-1beta, IL-6, IL-8, tumour necrosis factor alpha (TNF-alpha) and vascular endothelial growth factor. In the present study, 84 breast cancer patients were randomized to receive a daily supplement of CoQ(10) 100 mg, riboflavin 10 mg and niacin 50 mg, one dosage per day along with tamoxifen 10 mg twice a day. Serum cytokine levels were elevated in untreated breast cancer patients (Group II) and significantly reduced after tamoxifen therapy for more than 1 year (Group III). When group III breast cancer patients were supplemented with CoRN for 45 days (Group IV) and 90 days (Group V) along with tamoxifen, a significant reduction in cytokine levels were observed (P < 0.05). Such a decrease in serum cytokine levels after CoRN supplementation in breast cancer patients may suggest good prognosis and efficacy of the treatment, and might even offer protection from metastases and recurrence of cancer.