BENER Abstract No. 15054. THE PINEAL GLAND AND CANCER.
(Eng.) Ronco, A. L.; Halberg, F. [Natl. Cancer Registry of Uruguay, Natl. Inst. of Oncology, Pascual Costa 3259/1212, 11700 Montevideo, Uruguay (RR/A.L.R.); Chronobiology Labs., Univ. of Minnesota, Minneapolis, Minnesota (F.H.)] Anticancer Res 16(4A):2033-2040; 1996 (68 Refs).
The authors discussed physiological aspects of the pineal gland, links between pineal gland function and cancer, and the effects of EMFs on pineal gland function. The article also described other agents that can affect pineal function. The pineal gland and the major hormone it produces, melatonin, seem to play a role in modulating the immune system. This has led at least one investigator to refer to the pineal as an "oncostatic gland." Melatonin administered at physiologic concentrations, for example, suppresses the growth of some breast cancer cell lines while pinealectomy increases the growth and proliferation of certain cancers in vivo. In some studies, melatonin has shown oncostimulatory activity. The timing of melatonin administration determines whether it has oncostatic or oncostimulatory activity. Melatonin antagonizes the immunosuppressive effects of corticosteroids, increases the cytotoxic activity of natural killer (NK) cells, and reciprocally interacts with beta-endorphins, stimulating T-lymphocytic responses by acting on opioid receptors. Melatonin is reportedly cytotoxic as well as oncostatic for in vitro cultures of breast, ovary, and bladder cancer cells. A link has also been reported between melatonin and interleukin-2 (IL2) in patients with oat cell lung cancer. In these patients, IL2 therapy restored the normal nocturnal increase in pineal melatonin secretion, an effect that disappeared when treatment was interrupted. The circadian rhythmicity of melatonin secretion is altered in some cancer patients. Breast cancer patients have higher plasma melatonin concentrations in the morning than healthy patients. In patients with prostate cancer, urinary excretion, the midlevel, and the amplitude of the melatonin circadian rhythm are significantly lower than in healthy young men or men with benign prostate disease. Patients with primary breast cancer have a decreased melatonin level, and there is a progressive decrease in the nocturnal peak as a function of increasing tumor size. Increased incidence of breast cancer with age has been strongly associated with increased pineal gland calcification with age (on the average, 2% for 3-12 yr, 46% for 13-40 yr, and 60% for more than 40 yr old). However, there are large variations in these associations, depending on the population studied. There is evidence that EMFs can affect pineal gland function. In vivo studies have shown, for example, that magnetic fields can inhibit N-acetyl-transferase (an important enzyme in the melatonin biosynthetic pathway), abolish the nocturnal increase in melatonin secretion, and decrease urinary excretion of melatonin metabolites. The exposure levels that suppress pineal melatonin production in rats correspond to field strengths of 100-300 V/m. These levels are greater than those typically encountered domestically, but are comparable to exposure levels found in occupations presumed to have elevated EMF exposures, such as electricians, welders, and telephone operators. Although several theoretical models have been proposed to explain the interactions of EMFs with biological systems, it is difficult to explain the effects of low-frequency EMFs because energy transfers from the fields to living tissues are almost negligible, even at high intensities. The authors believe that the pineal gland is more likely to respond indirectly to changes transmitted via neuronal pathways than directly to an EMF. They suggest that EMFs can act as a "synchronizer" or as a "stimulus" that acts below the threshold of perception. They associated possible effects with radiofrequency exposures by referencing studies in which full-size saline-filled human models were irradiated with 63- to 70-MHz EMFs (near the natural resonance frequency). These dosimetry studies have shown that the head and neck receive the largest energy transfers, up to 28 times that of the total body average, when the model was not grounded and an "antenna effect" dominated. The greatest amount of energy absorption occurred in the hypothalamus and
thalamus regions, areas located near the pineal gland. The selective absorption of energy in this region could functionally disturb the pineal-hypothalamus network. Alcohol consumption reduces the nocturnal increase in melatonin production and, thus, alcoholic beverages are recognized as a risk factor for cancer, especially breast cancer, in humans. Seasonal increases in the melatonin peak occur in the winter when the solar day is shorter, and decreases occur in spring and summer months when the solar day is longer. The incidence of breast cancer increases in the spring and summer relative to the rest of the year. The authors concluded that the association between light exposure and pineal function should be investigated further. Light exposure involved with rotating shift work and night occupations could produce confounding factors when analyzing occupational EMF exposures.
BENER Digest Update is a current awareness journal published every March, June, September and December. The Digest summarizes the results of key EMF bioeffects research published in a broad spectrum of professional journals. It is the only print publication that regularly surveys the world's literature on EMF biological effects, including research that directly relates to possible adverse health effects from EMF exposure. In-depth, original abstracts provide detailed experimental results and multidisciplinary interpretation. Full bibliographic references plus author and subject indexes help the reader maintain a current overview of this expanding field. The Digest also features original articles on EMF biological effects. Ongoing research, meeting abstracts, and summaries of popular-press news articles are included as well. Each quarterly issue puts all the most recent EMF research at your fingertips in one concise journal.