A study on the relationship between the pineal gland and the opioid system in patients with cancer. Preliminary considerations.

Recent studies showed that both the pineal gland and the endogenous opioid system are involved in the modulation of the immune system and in the regulation of tumor growth. Moreover, a relationship between pineal and opioid system has been demonstrated. In order get an overall view of the psychoneuroendocrine interactions in cancer patients, the levels of melatonin, the most important pineal hormone, and of beta-endorphin have been measured on blood samples collected during the morning. The study was carried out on 54 patients, 42 healthy subjects, and in 34 patients having illnesses other than cancer. Breast cancer, lung carcinoma, and colorectum cancer were the three neoplasms detected in the patients investigated. Growth hormone (GH), somatomedin-C and prolactin (PRL) levels were also determined. beta-endorphin levels were found to be substantially within the normal range in patients with cancer, whereas those of melatonin were raised in several cases. The beta-endorphin/melatonin ratio was higher than 2 in normal subjects, in non-neoplastic patients and in most cancer patients without metastases, whereas this ratio was lower than 2 in almost all patients in a metastatic stage of the disease. Neither melatonin levels nor those of beta-endorphin appeared to be significantly correlated with GH, somatomedin-C, and PRL concentrations. The low beta-endorphin/melatonin ratio observed in metastatic patients suggests the presence of an unbalanced relation between the pineal and the opioid system in those subjects. Therefore, an anomalous relationship between pineal function and opioid activity might play a role in the clinical course of neoplastic disease.