The epidemiological studies have indicated a possible oncostatic property of melatonin on different types of tumors. significantly elevated the risk of breast tumor by about 21 instances more than the CC genotype (OR = 20.67; 95% CI = 4.77-99.33) [33]. Besides, a meta-analysis including 5 prospective case-control studies reported an inverse relationship between breast tumor risk and the highest levels of urinary aMT6h [34]. Another study evaluated the association between breast tumor risk and common solitary nucleotide polymorphismsin the (encoding arylalkylamine N-acetyltransferase) genes among 2,073 instances and 2,083 settings, and reported that common genetic variant in the and genes might contribute to breast tumor susceptibility, and the associations might vary 867334-05-2 IC50 with menopausal status [27]. A nested case-control study reported that a higher urinary aMT6h level was considerably connected with a lower risk of breast cancer (OR = 0.62; 95% CI, 0.41-0.95; P(trend) = 0.004) [35]. However, 4 case-control studies suggested there was no evidence that melatonin level was associated with breast cancer risk. A prospective nested case-control study among British women pointed out that no statistically significant differences in urinary 867334-05-2 IC50 aMT6s level between women with breast cancer and healthy women were observed, regardless of 867334-05-2 IC50 menopausal status [36]. Besides, a case-control study nested in the Women’s Health Initiative Observational Cohort reported there was no evidence that higher 867334-05-2 IC50 urinary levels of melatonin were inversely related with breast cancer risk in postmenopausal women [37]. Results from another case-control study nested within the Nurses’ Health Study II cohort also did not support an overall association between urinary melatonin levels and breast cancer risk [38]. Likewise, no significant association was found between aMT6s level and breast cancer risk (either overall or by menopausal status) in a case-control study nested in the Guernsey III Study [39]. Table 1 Epidemiological studies on melatonin level and cancer risks As for cancers other than breast cancer, a case-cohort study reported that men with first morning urinary aMT6s levels below the median possessed a fourfold higher risk of prostate cancer compared with men with levels above the median (HR: 4.04; 95% CI: 1.26-12.98) [40]. In addition, a case-control study pointed out that patients with high melatonin-sulfate levels or a high melatonin-sulfate/cortisol ratio were less likely to have prostate cancer (adjusted OR (aOR) = 0.59, 95% CI: 0.35-0.99; aOR = 0.46, 95% CI: 0.27-0.77) or advanced stage prostate (aOR = 0.49, 95% CI = 0.26-0.89; aOR = 0.33, 95% CI = 0.17-0.62) [41]. A retrospective study found that the serum melatonin levels in women with ovarian cancer were significantly lower compared with control subjects (< 0.05), indicating that reduction in Rabbit polyclonal to OPG circulating melatonin level might contribute to the pathogenesis of ovarian cancer [42]. Besides, according to a meta-analysis 867334-05-2 IC50 of RCTs, melatonin significantly improved the complete and partial remission (16.5 < 0.00001), 1-year survival rate (28.4 vs. 52.2%; RR = 1.90; 95% CI: 1.28-2.83; = 0.001) for solid tumors, and markedly decreased side effects induced by radiochemotherapy, including neurotoxicity, thrombocytopenia, and fatigue. Meanwhile, effects were accordant across different types of cancers [43]. Similarly, another meta-analysis summarizing 21 medical tests, which all dealt with solid tumors, exposed that melatonin as an adjuvant tumor treatment with chemotherapy reduced 1-yr fatality (RR = 0.60; 95% CI: 0.54-0.67), and reduced chemotherapy-induced symptoms such while asthenia, leucopenia, nausea, nausea, and hypotension [44]. Nevertheless, a nested case-control research demonstrated that no apparent association between urinary melatonin level and ovarian tumor risk was noticed [45]. It should become mentioned that in the existing epidemiological research, the strategies of melatonin evaluation are not really uniformed, since melatonin concentrations had been scored in different examples, such as urine, serum or plasma. Furthermore, the melatonin focus in human being body adjustments with circadian tempo, nevertheless, it offers not really been established which test collection period could greatest reveal the natural results of melatonin. These differences might result in the inconsistence of epidemiological research partially. In this full case, the.