Adjuvant therapy with the pineal hormone melatonin in patients with lymph node relapse due to malignant melanoma

Adjuvant melatonin for uveal melanoma (AMUM): protocol for a randomized open-label phase III study

BACKGROUND

Uveal melanoma is the most common primary intraocular tumor in adults. In Sweden, at least 100 patients are diagnosed with the disease each year. Almost half of the patients develop metastases, with a median survival time of 1 year once metastases are detected. The primary ocular tumor is typically treated with either enucleation or brachytherapy, and no adjuvant treatment is added. Melatonin is an indolamine hormone that has improved survival in previous trials with patients diagnosed with various cancers, including advanced cutaneous melanoma. Side effects have been mild. We aim to investigate if adjuvant treatment with melatonin for 5 years following diagnosis of non-metastasized uveal melanoma can decrease the occurrence of metastases.

METHODS

An open-label, prospective, 5-year randomized clinical trial (RCT) will be conducted at St. Erik Eye Hospital. One hundred patients recently diagnosed with non-metastatic uveal melanoma will be randomized to either treatment with adjuvant melatonin 20 mg (4 tablets of 5 mg) at 10 pm for 5 years, or to standard follow-up (control group). The primary outcome measurement is the relative risk for having developed metastases 5 years after randomization. The secondary outcomes are overall survival, risk of developing other cancers, overall survival after detection of metastases, and differences in the occurrence of adverse events (AE) and serious adverse events (SAE) between the groups.

DISCUSSION

Melatonin has been found to positively impact our immune system, inhibit angiogenesis, stimulate apoptosis in malignant cells, and act as a potent antioxidant. Previous clinical trials have used similar doses of melatonin with positive results, particularly in advanced stages of cancer. Previous animal and human studies have found the toxicity of the hormone to be low. Considering the potential benefits and limited risks of melatonin, as well as its global availability, it may be a suitable candidate for an adjuvant treatment in patients with uveal melanoma.

TRIAL REGISTRATION

Our trial protocol has been approved and registered by the Swedish Medical Products Agency on June 22, 2022 (EudraCT 2022-500,307-49-00). Our trial registration number is NCT05502900, and the date of registration is August 16, 2022.

The rationale for treating uveal melanoma with adjuvant melatonin: a review of the literature

Background

Uveal melanoma is a rare form of cancer with high mortality. The incidence of metastases is attributed to early seeding of micrometastases from the eye to distant organs, primarily the liver. Once these seeded clusters of dormant tumor cells grow into larger radiologically detectable macrometastases, median patient survival is about 1 year. Melatonin is an important hormone for synchronizing circadian rhythms. It is also involved in other aspects of human physiology and may offer therapeutic benefits for a variety of diseases including cancer.

Methods

Articles involving the physiological effects of melatonin, pharmacokinetics, and previous use in cancer studies were acquired using a comprehensive literature search in the Medline (PubMed) and Web of Science databases. In total, 147 publications were selected and included in the review.

Results

Melatonin has been observed to suppress the growth of cancer cells, inhibit metastatic spread, enhance immune system functions, and act as an anti-inflammatory in both in vitro and in vivo models. Melatonin may also enhance the efficacy of cancer treatments such as immuno- and chemotherapy. Numerous studies have shown promising results for oral melatonin supplementation in patients with other forms of cancer including cutaneous malignant melanoma. Cell line and animal studies support a hypothesis in which similar benefits may exist for uveal melanoma.

Conclusions

Given its low cost, good safety profile, and limited side effects, there may be potential for the use of melatonin as an adjuvant oncostatic treatment. Future avenues of research could include clinical trials to evaluate the effect of melatonin in prevention of macrometastases of uveal melanoma.

Melatonin and Metformin Failed to Modify the Effect of Dacarbazine in Melanoma

LESSONS LEARNED

Melatonin did not increase the efficacy of systemic chemotherapy in melanoma. Metformin did not increase the efficacy of systemic chemotherapy in melanoma.

BACKGROUND

Current data support the possibility of antitumor activity of melatonin and metformin.

METHODS

From March 2014 to December 2016, 57 patients with disseminated melanoma received dacarbazine (DTIC) 1,000 mg/m² on day 1 of a 28-day cycle, either as monotherapy (first group) or in combination with melatonin 3 mg p.o. daily (second group) or metformin 850 mg two times a day p.o. daily (third group) as the first-line of chemotherapy. The primary endpoint was objective response rate (ORR). Secondary endpoints were time to progression (TTP), overall survival (OS), immunologic biomarkers, and quality of life.

RESULTS

ORR was 7% and did not differ among the treatment groups. Median TTP was 57, 57, and 47 days, respectively, in the first, second, and third groups (р = .362). Median OS was 236, 422, and 419 days, respectively (p = .712). Two patients from the combinations groups showed delayed response to therapy. The increase of CD3⁺ CD4⁺ HLA-DR⁺ lymphocytes (p = .003), CD3⁺ CD8⁺ HLA-DR⁺ (p = .045), CD3⁺ CD8⁺ lymphocytes (p = .012), CD4⁺ CD25^high CD127^low lymphocytes (p = .029), and overall quantity of lymphocytes (p = .021) was observed in patients with clinical benefit.

CONCLUSION

No benefit was found in either combination over DTIC monotherapy. Delayed responses in melatonin and metformin combination groups were registered. The increase of lymphocyte subpopulations responsible for antitumor immune response demonstrates the immune system's potential involvement in clinical activity.

Effect of concomitant treatment of curcumin and melatonin on cisplatin-induced nephrotoxicity in rats

Cisplatin (CP) is a potent anticancer drug used to treat solid tumors. Its use, however, is dose-limited by its nephrotoxicity. We aimed to compare the effect of melatonin and curcumin given singly, with that of a combination of these two agents on CP-induced nephrotoxicity in rats. CP (6 mg/kg, given once intraperitoneally) induced nephrotoxicity as evidenced by several significant adverse physiological, biochemical and histopathological actions that included a reduction in body weight, increased urine production, and significant alterations in some conventional and novel renal damage indices in plasma, urine and kidneys. CP also elevated several pro-inflammatory cytokines and caused renal oxidative/nitrosative stress. Supplementation with either curcumin (200 mg/kg) or melatonin (10 mg /kg) given singly by oral gavage for eight consecutive days prior to CP injection and four days thereafter, significantly mitigated the adverse renal effects of CP, by attenuating the pro-inflammatory and apoptotic mediators and improving antioxidant competence in renal tissues of CP- treated rats. When curcumin and melatonin were given together, the ameliorative effect was augmented in some of the measured indices e.g. tumor necrosis factor alpha, cystatin C, uric acid, phosphorus in plasma and, urine creatinine and creatinine clearance. Renal platinum concertation was reduced more with curcumin than that with melatonin, while the reduction was maximized when both melatonin and curcumin were given. Pending further pharmacological and toxicological studies, a combination of these two agents is likely to be mor effective in mitigating the adverse renal effects of CP administered to cancer patients.

Melatonin: A new inhibitor agent for cervical cancer treatment

Cervical cancer is one of the most common cancers between women and is known as the third leading cause of female cancer related deaths annually. Its detection in early stages allows it to be a preventable and generally treatable disease. Increasing evidence revealed, a variety of internal and external factors are associated with initiation and progression of cervical cancer pathogenesis. Human papilloma virus infection is found as a major cause of cervical cancer. Other molecular and biochemical alterations as well as genetic and epigenetic changes are related cervical cancer progression. Current treatment options often have severe side effects and toxicities thus, new adjuvant agents having synergistic effects and ability to decrease different side effects and toxicities are needed. Melatonin is an indolamine compound secreted from the pineal gland which shows wide range anticancer activities. A large amount of studies indicated inhibitory effects of melatonin against various types of cancers. In addition, experimental evidence reports inhibitory effects of melatonin as an adjuvant therapy on cervical cancer by targeting a sequence of different molecular mechanisms. Herein, for first time, we summarized anticervical cancer effects of melatonin and its underlying molecular mechanisms.

Melatonin May Increase Anticancer Potential of Pleiotropic Drugs

Melatonin (N-acetyl-5-methoxytryptamine) is not only a pineal hormone, but also an ubiquitary molecule present in plants and part of our diet. Numerous preclinical and some clinical reports pointed to its multiple beneficial effects including oncostatic properties, and as such, it has become one of the most aspiring goals in cancer prevention/therapy. A link between cancer and inflammation and/or metabolic disorders has been well established and the therapy of these conditions with so-called pleiotropic drugs, which include non-steroidal anti-inflammatory drugs, statins and peroral antidiabetics, modulates a cancer risk too. Adjuvant therapy with melatonin may improve the oncostatic potential of these drugs. Results from preclinical studies are limited though support this hypothesis, which, however, remains to be verified by further research.

Therapeutic strategies of melatonin in cancer patients: a systematic review and meta-analysis

Background

Melatonin (MLT), a kind of neuroendocrine active substance, has been reported to function in the treatment of tumors. However, there remain controversies about the curative effect of MLT in tumors in clinical studies. This study investigates the efficacy of MLT on tumor therapeutic strategies by meta-analysis.

Methods

After searching several main literature databases, a total of 5,057 articles were obtained and screened by inclusion and exclusion criteria. The tumor remission rate, overall survival rate, and incidence of side effects were recorded and analyzed in the included study patients. Group analysis and sensitivity analysis were performed to examine the sources of heterogeneity in the pooled studies.

Results

The tumor remission rate in the MLT group was significantly higher than that in the control group (relative risk [RR] =2.25; 95% CI, 1.86–2.71; P<0.00001; I²=9%). Likewise, the MLT group had an overall survival rate of 28.24% (n=294/1,041), which was greatly increased compared with the control group (RR =2.07; 95% CI, 1.55–2.76; P<0.00001; I²=55%). And, MLT could significantly enhance the overall survival rate in non-small-cell lung cancer patients (RR =2.13; 95% CI, 1.41–3.24; P=0.0004; I²=0%) and various solid tumor patients (RR =2.31; 95% CI, 1.78–2.99; P<0.00001; I²=0%). It was further proved that MLT could effectively reduce the incidence of neurotoxicity (RR =0.30, 95% CI, 0.19–0.45; P<0.00001), thrombocytopenia (RR =0.23; 95% CI, 0.16–0.33; P<0.00001), and asthenia (RR =0.43, 95% CI, 0.38–0.49; P<0.00001) during chemotherapy.

Conclusion

MLT exerts positive influence in tumor therapeutic strategies, including improving tumor remission rate and overall survival rate, while reducing the incidence of chemotherapy side effects. Further large-scale randomized clinical trials (RCTs) are urgently required to verify therapeutic effects of MLT in tumors by various clinical research centers.

Melatonin: A Cutaneous Perspective on its Production, Metabolism, and Functions

Melatonin, an evolutionarily ancient derivative of serotonin with hormonal properties, is the main neuroendocrine secretory product of the pineal gland. Although melatonin is best known to regulate circadian rhythmicity and lower vertebrate skin pigmentation, the full spectrum of functional activities of this free radical-scavenging molecule, which also induces/promotes complex antioxidative and DNA repair systems, includes immunomodulatory, thermoregulatory, and antitumor properties. Because this plethora of functional melatonin properties still awaits to be fully appreciated by dermatologists, the current review synthesizes the main features that render melatonin a promising candidate for the management of several dermatoses associated with substantial oxidative damage. We also review why melatonin promises to be useful in skin cancer prevention, skin photo- and radioprotection, and as an inducer of repair mechanisms that facilitate the recovery of human skin from environmental damage. The fact that human skin and hair follicles not only express functional melatonin receptors but also engage in substantial, extrapineal melatonin synthesis further encourages one to systematically explore how the skin's melatonin system can be therapeutically targeted in future clinical dermatology and enrolled for preventive medicine strategies.

The therapeutic application of melatonin in supportive care and palliative medicine

Melatonin is a hormone produced mainly in the pineal gland. Plasma levels exhibit a circadian variation with the highest concentration occurring at night. The human biologic effects of melatonin depend upon the time of day it is made available. One of these effects is the setting and resetting of circadian clocks (chronobiotic effect). Additionally, it may be a potent antioxidant and immunomodulator and has been shown to have anti-tumor, anticytokine, anti-insomnia, and anticachexia effects. Melatonin has also been shown to improve survival and performance status in patients with advanced cancer. Objective tumor response occurs with melatonin alone or when combined with interleukin-2 (IL-2). Further, melatonin reduces radiation- and chemotherapeutic-induced toxicity. Symptomatic and circadian disruption is linked to increased cancer risk. The chronobiotic capacity of melatonin to reset circadian clocks may provide a verifiable strategy to reduce cancer risk and enhance quality of life by diminishing cancer-induced circadian disruption.

Circadian Dysrhythmias, Physiological Aberrations, and the Link to Skin Cancer

Circadian rhythms are core regulators of a variety of mammalian physiologic processes and oscillate in a 24-h pattern. Many peripheral organs possess endogenous rhythmicity that is then modulated by a master clock; the skin is one of these peripheral organs. The dysregulation of rhythms is associated with decreased ability to ameliorate cellular stressors at a local and global level, which then increases the propensity for the development of neoplastic growths. In this article, we review the implications of altered circadian rhythms on DNA repair as well as modified gene expression of core clock proteins with particular focus on skin models. These findings are then correlated with epidemiologic data regarding skin cancer to showcase the effects of circadian disruption on this phenomenon.

Evaluating the Oxidative Stress in Inflammation: Role of Melatonin

Oxygen is used by eukaryotic cells for metabolic transformations and energy production in mitochondria. Under physiological conditions, there is a constant endogenous production of intermediates of reactive oxygen (ROI) and nitrogen species (RNI) that interact as signaling molecules in physiological mechanisms. When these species are not eliminated by antioxidants or are produced in excess, oxidative stress arises. Oxidative stress can damage proteins, lipids, DNA, and organelles. It is a process directly linked to inflammation; in fact, inflammatory cells secrete a large number of cytokines and chemokines responsible for the production of ROI and RNI in phagocytic and nonphagocytic cells through the activation of protein kinases signaling. Currently, there is a wide variety of diseases capable of producing inflammatory manifestations. While, in the short term, most of these diseases are not fatal they have a major impact on life quality. Since there is a direct relationship between chronic inflammation and many emerging disorders like cancer, oral diseases, kidney diseases, fibromyalgia, gastrointestinal chronic diseases or rheumatics diseases, the aim of this review is to describe the use and role of melatonin, a hormone secreted by the pineal gland, that works directly and indirectly as a free radical scavenger, like a potent antioxidant.

The expanding roles of 1-methyl-tryptophan (1-MT): in addition to inhibiting kynurenine production, 1-MT activates the synthesis of melatonin in skin cells

Indoleamine 2,3-dioxygenase 1 (IDO1), the rate-limiting enzyme of tryptophan catabolism, has been strongly associated with the progression of malignancy and poor survival in melanoma patients. As a result, IDO1 is a leading target for interventions aimed at restoring melanoma immune surveillance. Here, in a scenario involving the tryptophan catabolism, we report that melatonin biosynthesis is driven by 1-methyl-tryptophan (1-MT), a competitive inhibitor of IDO1, in human fibroblasts, melanocytes and melanoma cells. In addition to melatonin biosynthesis, 1-MT induced the expression of tryptophan hydroxylase, arylalkylamine-N-acetyltransferase and hydroxyindole O-methyltransferase mRNA in fibroblasts and melanocytes. We observed a great variability in the levels of IDO1 mRNA expression and kynurenine release between skin cells and melanoma cell lines in response to interferon-γ, a classical IDO1 inducer. In this setting, melatonin was shown to downregulate kynurenine production. Furthermore, in a condition of low basal activity of IDO1, it was observed that 1-MT, as well melatonin, inhibited the proliferation of human melanoma cells. Taken together, our results suggest that 1-MT may serve as more than just a tool to disrupt tumor immune escape (via the inhibition of IDO1) because it was shown to act directly on the proliferation of human melanoma cells and induce melatonin biosynthesis in the tumor milieu. Moreover, 1-MT-mediated inhibition of IDO occurs in normal skin and melanoma cells, which addresses the possibility that all cells in the skin microenvironment can be targeted by 1-MT. Our findings provide innovative approaches into understanding tumor therapy related to the control of tryptophan metabolism by 1-MT.

The efficacy and safety of melatonin in concurrent chemotherapy or radiotherapy for solid tumors: a meta-analysis of randomized controlled trials

BACKGROUND

Recently, melatonin has been associated with cancer both in vitro and in vivo. However, the value of melatonin in the treatment of cancer remains disputable. Hence, we performed a systematic review of randomized controlled trials (RCTs) of melatonin in solid tumor cancer patients and observed its effect on tumor remission, 1-year survival, and side effects due to radiochemotherapy.

METHODS

An electronic search was conducted using the databases Pubmed, Medline, EMBASE, Cochrane library, and CNKI, from inception to November 2011. Trials using melatonin as adjunct treatment concurrent with chemotherapy or radiotherapy for cancer were included. Pooled relative risk (RR) for the tumor remission, 1-year survival, and radiochemotherapy-related side effects were calculated using the software Revman 5.0.

RESULTS

The search strategy identified 8 eligible RCTs (n = 761), all of which studied solid tumor cancers. The dosage of melatonin used in the 8 included RCTs was 20 mg orally, once a day. Melatonin significantly improved the complete and partial remission (16.5 vs. 32.6%; RR = 1.95, 95% CI, 1.49-2.54; P < 0.00001) as well as 1-year survival rate (28.4 vs. 52.2%; RR = 1.90; 95% CI, 1.28-2.83; P = 0.001), and dramatically decreased radiochemotherapy-related side effects including thrombocytopenia (19.7 vs. 2.2%; RR = 0.13; 95% CI, 0.06-0.28; P < 0.00001), neurotoxicity (15.2 vs. 2.5%; RR = 0.19; 95% CI, 0.09-0.40; P < 0.0001), and fatigue (49.1 vs. 17.2%; RR = 0.37; 95% CI, 0.28-0.48; P < 0.00001). Effects were consistent across different types of cancer. No severe adverse events were reported.

CONCLUSIONS

Melatonin as an adjuvant therapy for cancer led to substantial improvements in tumor remission, 1-year survival, and alleviation of radiochemotherapy-related side effects.

Melatonin as adjuvant cancer care with and without chemotherapy: a systematic review and meta-analysis of randomized trials

BACKGROUND

Melatonin (MLT) is known to possess potent antioxidant, antiproliferative, immune-modulating, and hormone-modulating properties. Clinical evidence suggests that MLT may have a possible role in the treatment of cancer. The authors systematically reviewed the effects of MLT in conjunction with chemotherapy, radiotherapy, supportive care, and palliative care on 1-year survival, complete response, partial response, stable disease, and chemotherapy-associated toxicities.

METHODS

The authors searched 7 databases: MEDLINE (1966-February 2010), AMED (1985-February 2010), Alt HealthWatch (1995-February 2010), CINAHL (1982-February 2010), Nursing and Allied Health Collection: Basic (1985-February 2010), the Cochrane Database (2009), and the Chinese database CNKI (1979-February 2010). They included all trials that randomized patients to treatment, including MLT or a similar control group without MLT.

RESULTS

The authors included data from 21 clinical trials, all of which dealt with solid tumors. The pooled relative risk (RR) for 1-year mortality was 0.63 (95% confidence interval [CI] = 0.53-0.74; P < .001). Improved effect was found for complete response, partial response, and stable disease with RRs of 2.33 (95% CI = 1.29-4.20), 1.90 (1.43-2.51), and 1.51 (1.08-2.12), respectively. In trials combining MLT with chemotherapy, adjuvant MLT decreased 1-year mortality (RR = 0.60; 95% CI = 0.54-0.67) and improved outcomes of complete response, partial response, and stable disease; pooled RRs were 2.53 (1.36-4.71), 1.70 (1.37-2.12), and 1.15 (1.00-1.33), respectively. In these studies, MLT also significantly reduced asthenia, leucopenia, nausea and vomiting, hypotension, and thrombocytopenia.

CONCLUSION

MLT may benefit cancer patients who are also receiving chemotherapy, radiotherapy, supportive therapy, or palliative therapy by improving survival and ameliorating the side effects of chemotherapy.

Molecular Mechanisms of Melatonin Anticancer Effects

The authors have shown that, via activation of its MT1 receptor, melatonin modulates the transcriptional activity of various nuclear receptors and the proliferation of both ERα+ and ERα- human breast cancer cells. Employing dominant-negative (DN) and dominant-positive (DP) G proteins, it was demonstrated that Gα i2 proteins mediate the suppression of estrogen-induced ERα transcriptional activity by melatonin, whereas the Gαq proteins mediate the enhancement of retinoid-induced RARα transcriptional activity by melatonin. In primary human breast tumors, the authors’ studies demonstrate an inverse correlation between ERα and MT1 receptor expression, and confocal microscopic studies demonstrate that the MT1I receptor is localized to the caveoli and that its expression can be repressed by estrogen and melatonin. Melatonin, via activation of its MT1 receptor, suppresses the development and growth of breast cancer by regulation of growth factors, regulation of gene expression, regulation of clock genes, inhibition of tumor cell invasion and metastasis, and even regulation of mammary gland development. The authors have previously reported that the clock gene, Period 2 ( Per2), is not expressed in human breast cancer cells but that its reexpression in breast cancer cells results in increased expression of p53 and induction of apoptosis. The authors demonstrate that melatonin, via repression of RORα transcriptional activity, blocks the expression of the clock gene BMAL1 . Melatonin’s blockade of BMAL1 expression is associated with the decreased expression of SIRT1, a member of the Silencing Information Regulator family and a histone and protein deacetylase that inhibits the expression of DNA repair enzymes (p53, BRCA1 & 2, and Ku70) and the expression of apoptosis-associated genes. Finally, the authors developed an MMTV-MT1-flag mammary knock-in transgenic mouse that displays reduced ductal branching, ductal epithelium proliferation, and reduced terminal end bud formation during puberty and pregnancy. Lactating female MT1 transgenic mice show a dramatic reduction in the expression of β-casein and whey acidic milk proteins. Further analyses showed significantly reduced ERα expression in mammary glands of MT1 transgenic mice. These results demonstrate that the MT1 receptor is a major transducer of melatonin’s actions in the breast, suppressing mammary gland development and mediating the anticancer actions of melatonin through multiple pathways.

The melatonin-producing system is fully functional in retinal pigment epithelium (ARPE-19)

Since melatonin production has been documented in extrapineal and extraneuronal tissues, we investigated the expression of molecular elements of the melatoninergic system in human RPE cells (ARPE-19). The expression of key enzymes for melatonin synthesis: tryptophan hydroxylases (TPH1 and TPH2); arylalkylamine N-acetyltransferase (AANAT) and hydroxyindole-O-methyltransferase (HIOMT) was detected in ARPE-19 cells using RT-PCR. TPH1 and AANAT proteins were detected in ARPE by Western blotting, while sequential metabolism of tryptophan, serotonin and N-acetylserotonin to melatonin was shown by RP-HPLC. We also demonstrated, by means of RT-PCR, that ARPE expressed mRNA encoding the melatonin receptors: MT2 (but not MT1), two isoforms of nuclear receptor (RORalpha1 and RORalpha4/RZR1), and quinone oxidoreductase (NQO2). By analogy with other peripheral tissues, for example the skin, the expression of these metabolic elements in RPE cells suggests that the RPE represents an additional source of melatonin in the eye, to regulate local homeostasis and prevent from oxidative damage in intra-, auto- and/or paracrine fashions.

Randomized phase II trial of high-dose melatonin and radiation therapy for RPA class 2 patients with brain metastases (RTOG 0119)

PURPOSE

To determine if high-dose melatonin for Radiation Therapy Oncology Group (RTOG) recursive partitioning analysis (RPA) Class 2 patients with brain metastases improved survival over historical controls, and to determine if the time of day melatonin was given affected its toxicity or efficacy. RTOG 0119 was a phase II randomized trial for this group of patients.

METHODS AND MATERIALS

RTOG RPA Class 2 patients with brain metastases were randomized to 20 mg of melatonin, given either in the morning (8-9 AM) or in the evening (8-9 PM). All patients received radiation therapy (30 Gy in 10 fractions) in the afternoon. Melatonin was continued until neurologic deterioration or death. The primary endpoint was overall survival time. Neurologic deterioration, as reflected by the Mini-Mental Status Examination, was also measured.

RESULTS

Neither of the randomized groups had survival distributions that differed significantly from the historic controls of patients treated with whole-brain radiotherapy. The median survivals of the morning and evening melatonin treatments were 3.4 and 2.8 months, while the RTOG historical control survival was 4.1 months.

CONCLUSIONS

High-dose melatonin did not show any beneficial effect in this group of patients.

Primer on integrative oncology

At the present time, there is no obvious answer for many of these design difficulties. This problem will continue to constrain ability to determine the efficacy of integrative medical techniques for patients who have cancer. Patients, however, will continue to gravitate toward alternative treatments, especially when standard cancer treatments fail. Therefore oncologists must be aware of alternative medical agents and techniques, and be able to guide their patients, rather than simply being dismissive.

Melatonin in the treatment of cancer: a systematic review of randomized controlled trials and meta-analysis

Most observational studies show an association between melatonin and cancer in humans. We conducted a systematic review of randomized controlled trials (RCTs) of melatonin in solid tumor cancer patients and its effect on survival at 1 yr. With the aid of an information specialist, we searched 10 electronic databases from inception to October 2004. We included trials using melatonin as either sole treatment or as adjunct treatment. Prespecified criteria guided our assessment of trial quality. We conducted a meta-analysis using a random effects model. We included 10 RCTs published between 1992 and 2003 and included 643 patients. All trials included solid tumor cancers. All trials were conducted at the same hospital network, and were unblinded. Melatonin reduced the risk of death at 1 yr (relative risk: 0.66, 95% confidence interval: 0.59-0.73, I2=0%, heterogeneity P<or=0.56). Effects were consistent across melatonin dose, and type of cancer. No severe adverse events were reported. The substantial reduction in risk of death, low adverse events reported and low costs related to this intervention suggest great potential for melatonin in treating cancer. Confirming the efficacy and safety of melatonin in cancer treatment will require completion of blinded, independently conducted RCTs.

An Approach to Teaching Dermatologists About Complementary Medicine

OBJECTIVES

There is increasing evidence for the extensive use of complementary and alternative medicine (CAM) among patients with dermatologic ailments amid a scarcity of information about teaching health providers on how to engage with patients who use CAM or request information about it. An approach to educating dermatologists and nurses about CAM is described in this paper.

DESIGN

A course on CAM and dermatology was offered to 17 dermatologists and nurses at a dermatology department in a university hospital in Israel. The course objective was to expose participants to common methods in CAM, emphasizing the role of an evidence-based approach and patient-doctor communication relating to CAM.

RESULTS

Course evaluation revealed that participants acknowledged the existence of evidence-based research as an important consideration before referring their patients to CAM.

CONCLUSIONS

Teaching CAM to dermatologists and nurses using evidence-based medicine and a patient-centered approach could enable them to provide informed and balanced advice to their patients.

Melatonin biological activity and binding sites in human melanoma cells

The effects of melatonin, N-acetylserotonin and serotonin on the growth and tyrosinase activity of SK-Mel 23 and SK-Mel 28 human melanoma cell lines were investigated. Binding assays were also performed to establish the nature of the binding site. SK-Mel 28 cells were responsive to melatonin and its precursors, exhibiting a decrease in growth and an increase in tyrosinase activity after a 72 hr treatment. N-acetylserotonin was as potent as melatonin, the minimal effective concentration (MEC, which is defined as the smallest concentration that elicits a measurable biological response, significantly different from control) being 10-8 m. Serotonin was the least potent (MEC = 10-6 m). Both melatonin antagonists, prazosin and luzindole, exhibited no effect per se and reversed both responses to melatonin. SK-Mel 23 cells, however, showed no significant responses to the indoleamines. Competition binding assays in SK-Mel 28 cells demonstrated the presence of binding sites to 2-[125 I]-iodomelatonin, which was displaced by the unlabelled hormone, by both antagonists, and by N-acetylserotonin. The curve adjustment of the displacement values with melatonin suggests the existence of two binding sites, with the following Ki values: 1.0 x 10-10 m and 6.5 x 10-6 m. Ki values for acetylserotonin, prazosin and luzindole were, respectively, 3.8 x 10-8 m, 1.2 x 10-8 m, and 8.3 x 10-6 m. Surprisingly, in SK-Mel 23 cells, melatonin and luzindole were able to compete with the radioligand, with Ki values of 3.1 x 10-8 and 2.4 x 10-8 m, respectively. Our data suggest that SK-Mel 28 cells probably possess high affinity binding sites to melatonin and, in addition, MT3 low affinity binding sites, because N-acetylserotonin was as effective as the native hormone, and prazosin effectively blocked the actions of melatonin. Both sites are functional as demonstrated by the blockade promoted by both luzindole and prazosin on the proliferative and melanogenic responses. Although growth and tyrosinase activity of SK-Mel 23 cells were not affected by melatonin or its precursors, this cell line possesses high affinity binding sites, which may be non-functional, or trigger responses other than the ones herein investigated.

Melatonin: from basic research to cancer treatment clinics

Melatonin, the chief secretory product of the pineal gland, is a direct free radical scavenger, an indirect antioxidant, as well as an important immunomodulatory agent. In both in vitro and in vivo investigations, melatonin protected healthy cells from radiation-induced and chemotherapeutic drug-induced toxicity. Furthermore, several clinical studies have demonstrated the potential of melatonin, either alone or in combination with traditional therapy, to yield a favorable efficacy to toxicity ratio in the treatment of human cancers. This study reviews the literature from laboratory investigations that document the antioxidant and oncostatic actions of melatonin and summarizes the evidence regarding the potential use of melatonin in cancer treatment. This study also provides rationale for the design of larger translational research-based clinical trials.

Exogenous melatonin: quantitative enhancement in vivo of cells mediating non-specific immunity

Melatonin (MLT), a biogenic indoleamine and neuromodulator produced by the pineal gland, is known to activate T helper cells by means of direct binding to melatonin receptors on both Th1 and Th2 cells. The present in vivo study aimed to investigate the effect of exogenously administered MLT on the hemopoietic and immune cell populations of the bone marrow and spleen in healthy, young adult male mice at two distinct MLT exposure intervals. The neurohormone, administered daily through the diet (7-14 days), was homogenized into finely ground chow. Control mice received ground chow without MLT. The results revealed cell lineage-specific, quantitative, MLT exposure-time-dependent changes in both the bone marrow and spleen. NK cells and monocytes (both components of the non-specific immune system functioning as the first line of defense against neoplasia and virus infected cells) were significantly increased in the bone marrow by both 7 and 14 days of dietary melatonin. The quantitative increment in these two cell populations, in the organ of their production, i.e. the bone marrow, indicates that new cell proliferation/production may have been stimulated by MLT. In the spleen, as in the bone marrow, NK cell levels remained significantly elevated at both 7 and 14 days after melatonin exposure. However, the number of monocytes in the spleen did not maintain, at day 14 of MLT exposure, the high levels observed after 7 days of MLT, in spite of their sustained, high numbers at 14 days in the bone marrow. This suggests that the progeny of the apparently increased monocyte production in the bone marrow (elevated absolute numbers therein), had localized in anatomical sites (other than the spleen) also common to these cells. Thus, the selective, positive influences of in vivo administered, exogenous melatonin on cells mediating non-specific immunity suggests a plausible mechanism for numerous claims that it is responsible for tumor amelioration in patients.

Incidence of cancer among commercial airline pilots

OBJECTIVES

To describe the cancer pattern in a cohort of commercial pilots by follow up through the Icelandic Cancer Registry.

METHODS

This is a retrospective cohort study of 458 pilots with emphasis on subcohort working for an airline operating on international routes. A computerised file of the cohort was record linked to the Cancer Registry by making use of personal identification numbers. Expected numbers of cancer cases were calculated on the basis of number of person-years and incidences of cancer at specific sites for men provided by the Cancer Registry. Numbers of separate analyses were made according to different exposure variables.

RESULTS

The standardised incidence ratio (SIR) for all cancers was 0.97 (95% confidence interval (95% CI) 0.62 to 1.46) in the total cohort and 1.16 (95% CI 0.70 to 1.81) among those operating on international routes. The SIR for malignant melanoma of the skin was 10.20, 95% CI 3.29 to 23.81 in the total cohort and 15.63, 95% CI 5.04 to 36.46 in the restricted cohort. Analyses according to number of block-hours and radiation dose showed that malignant melanomas were found in the subgroups with highest exposure estimates, the SIRs were 13.04 and 28.57 respectively. The SIR was 25.00 for malignant melanoma among those who had been flying over five time zones.

CONCLUSIONS

The study shows a high occurrence of malignant melanoma among pilots. It is open to discussion what role exposure of cosmic radiation, numbers of block-hours flown, or lifestyle factors--such as possible excessive sunbathing--play in the aetiology of cancer among pilots. This calls for further and more powerful studies. The excess of malignant melanoma among those flying over five time zones suggests that the importance of disturbance of the circadian rhythm should be taken into consideration in future studies.

The validity of melatonin as an oncostatic agent

The validity of melatonin as a prominent, naturally occurring oncostatic agent is examined in terms of its putative oncostatic mechanism of action, the correlation between melatonin levels and neoplastic activity, and the outcome of therapeutically administered melatonin in clinical trials. Melatonin's mechanism of action is summarized in a brief analysis of its actions at the cellular level, its antioxidative functions, and its indirect immunostimulatory effects. The difficulties of interpreting melatonin levels as a diagnostic or prognostic aid in cancer is illustrated by referral to breast cancer, the most frequently studied neoplasm in trials regarding melatonin. Trials in which melatonin was used therapeutically are reviewed, i.e., early studies using melatonin alone, trials of melatonin in combination with interleukin-2, and controlled studies comparing routine therapy to therapy in combination with melatonin. A table compiling the studies in which melatonin was used in the treatment of cancer in humans is presented according to the type of neoplasm. Melatonin's suitability in combination chemotherapy, where it augments the anticancer effect of other chemotherapeutic drugs while decreasing some of the toxic side effects, is described. Based on the evidence derived from melatonin's antiproliferative, antioxidative, and immunostimulatory mechanisms of action, from its abnormal levels in cancer patients and from clinical trials in which melatonin was administered, it is concluded that melatonin could indeed be considered a physiological anticancer substance. Further well-controlled trials should, however, be performed in order to find the link between its observed effects and the underlying mechanisms of action and to define its significance as a therapeutic oncostatic agent.