Abstract
Clinical studies have demonstrated an altered pineal function in cancer patients. Owing to the documented antineoplastic activity of the pineal gland, these anomalies could have a prognostic significance. This study was carried out to monitor changes in blood levels of melatonin, the most important pineal hormone, in relation to the clinical response to chemotherapy in human neoplasms. The study included 42 cancer patients of both sexes (breast cancer, 10; lung cancer, 13; colon cancer, 11; soft tissue sarcoma, 4; testicular cancer, 1; Hodgkin's disease, 1; peritoneal mesothelioma, 2). Melatonin serum levels were measured by radioimmunoassay before and 28 days after each cycle of chemotherapy. The results showed that, irrespectively of the type of tumor and chemotherapeutic regimen, 12/16 patients (75%) whose melatonin markedly enhanced after chemotherapy had an objective regression. In contrast, 2/26 patients only (8%) whose melatonin did not enhance after chemotherapy had a clinical response. The percentage of objective responses was statistically significantly higher in patients with a chemotherapy-induced melatonin increase than in those with no melatonin increase (p < 0.001). This study seems to demonstrate that melatonin determination can be used as a predictor of the objective response to chemotherapy in cancer patients. Moreover, it suggests that the antineoplastic effect of cytotoxic drugs may require participation of the pineal gland.
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