Artificial Light at Night of Different Spectral Compositions Differentially Affects Tumor Growth in Mice: Interaction With Melatonin and Epigenetic Pathways.

Lighting technology is rapidly advancing toward shorter wavelength illuminations that offer energy-efficient properties. Along with this advantage, the increased use of such illuminations also poses some health challenges, particularly breast cancer progression. Here, we evaluated the effects of artificial light at night (ALAN) of 4 different spectral compositions (500-595 nm) at 350 Lux on melatonin suppression by measuring its urine metabolite 6-sulfatoxymelatonin, global DNA methylation, tumor growth, metastases formation, and urinary corticosterone levels in 4T1 breast cancer cell-inoculated female BALB/c mice. The results revealed an inverse dose-dependent relationship between wavelength and melatonin suppression. Short wavelength increased tumor growth, promoted lung metastases formation, and advanced DNA hypomethylation, while long wavelength lessened these effects. Melatonin treatment counteracted these effects and resulted in reduced cancer burden. The wavelength suppression threshold for melatonin-induced tumor growth was 500 nm. These results suggest that short wavelength increases cancer burden by inducing aberrant DNA methylation mediated by the suppression of melatonin. Additionally, melatonin suppression and global DNA methylation are suggested as promising biomarkers for early diagnosis and therapy of breast cancer. Finally, ALAN may manifest other physiological responses such as stress responses that may challenge the survival fitness of the animal under natural environments.

Preliminary studies on application of library of artificial receptors for differentiation of metabolites in urine of healthy and cancer bearing mice.

A library of artificial receptors formed by the self-organization of N-lipidated peptides attached to the cellulose via m-aminophenylamino-1,3,5-triazine was used for differentiation of metabolites in urine of healthy and cancer bearing mice. The interactions of urine metabolites with the receptors were visualized by using competitive adsorption-desorption of an appropriate reporter dye. Analysis of the binding pattern (fingerprint) of urine metabolites from healthy and from cancer suffering mice showed that there were several structures among 120-elements molecular receptors which were able to differentiate bonded ligands depending on the healthy state. For all three tested types of cancers two structures: Lipid-Pro-Ala-NH-C6H4-NH-DMT-cellulose and Lipid-Arg-Pro-NH-C6H4-NH-DMT-cellulose were selected as diagnostic.

Effect of dietary supplementation on the prognostic value of urinary and serum 8-isoprostaglandin F2α in chemically-induced mammary carcinogenesis in the rat.

BACKGROUND: The aim of the present study was to assess the effects of zinc or copper and polyphenolic compounds on the 8-isoprostaglandin F2α concentration in the serum and urine of rats with mammary cancer (adenocarcinoma) induced with 7,12-dimethylbenz[a]antracene. The research focused on the kinetics of alterations in urinary 8-isoPGF2α at the early stage of carcinogenesis as well as the influence of dietary factors on the process. The impact of selected compounds on the intensity of DMBA--induced carcinogenesis was also assessed. RESULT AND CONCLUSIONS: Administration of DMBA, a compound that inducers mammary tumors in experimental animals, increased the serum and urinary 8-isoPGF2α levels in study rats. In the rat model, diet supplementation with zinc, combined with selected polyphenolic compounds (resveratrol or genistein) yielded a statistically significant decrease in the rat serum and urinary biomarker concentration with a simultaneously significant stimulation of carcinogenesis.The results indicate that there is an inverse correlation between the intensity of DMBA-induced carcinogenicity and the level of 8-isoPGF2α in urine and serum of rats.

Positive urinary cytology in patients with lung cancer in the absence of obvious urine tract metastases.

PURPOSE: To study the phenomenon of positive urine cytology in patients with lung cancer in the absence of obvious urothelial metastases. PATIENTS AND METHODS: 150 patients with small (SCLC) and non-small cell lung cancer (NSCLC) of all stages and 3 control groups were prospectively studied. Immunocytochemical study (cytokeratins 7-20, TTF1) in all positive urine specimens and chemokine profile (CXCR4, CCL21) study of the primary tumor in selected positive patients was performed. In experimental study, C57Bl/6 BALB/C mice injected with LLC lung and 4T1 mammary cancer cells were used for the detection of positive urine cytology. RESULTS: 11% of patients with NSCLC, 7% of patients with SCLC and none of the control group had positive urine cytology. In NSCLC, metastatic disease and high tumor burden positively correlated (p=0.01 and 0.03 respectively) with the phenomenon. In SCLC, correlation with extensive disease and multiple metastatic sites (p=0.02 and 0.04 respectively) was found. No correlation was found in either group with: age, gender, histology, performance status, line of chemotherapy, previous platinum-based chemotherapy, adrenal metastases, renal function, abnormal urinary sediment, response to chemotherapy and overall survival (p=0.9). Distinctive chemokine expression was identified in positive patients studied and was not observed in negative patients (×2 p=0.008). In the experimental study, only the LLC lung cancer cells were detected in the urine cytology of mice. CONCLUSION: This phenomenon, carrying undefined pathophysiological mechanisms, seems to characterize only patients with metastatic/extensive disease and high tumor burden. Further studies are needed to validate our preliminary chemokine expression results.

Biodistribution of antisense nanoparticles in mammary carcinoma rat model.

Efficient and specific delivery of antisenses (ASs) and protection of the sequences from degradation are critical factors for effective therapy. Sustained release nanoparticles (NP) offer increased resistance to nuclease degradation, increased amounts of AS uptake, and the possibility of control in dosing and sustained duration of AS administration. The biodegradable and biocompatible poly(D,L-lactic-co-glycolic acid) copolymer (PLGA) was utilized to encapsulate AS directed against osteopontin (OPN), which is a promising therapeutic target in mammary carcinoma. Whole body biodistribution of OPN AS NP was evaluated in comparison to naked AS, in intact and mammary carcinoma metastasis model bearing rats. Naked and NP encapsulated AS exhibited different biodistribution profiles. AS NP, in contrast to naked AS, tended to accumulate mostly in the spleen, liver, and at the tumor inoculation site. Drug levels in intact organs were negligible. The elimination of naked AS was faster, due to rapid degradation of the unprotected sequence. It is concluded that AS NP protect the AS from degradation, provide efficient AS delivery to the tumor tissue, and minimize AS accumulation in intact organs due to the AS sustained release profile as well as the favorable NP physicochemical properties.

Urinary phytoestrogen excretion of rats bearing methylnitrosourea-induced mammary carcinoma in response to treatment with 2-methoxyestradiol.

The effect of treating mammary tumor-bearing rats with 2-methoxyestradiol (2-MeE2) on the urinary excretion of 12 phytoestrogens was investigated and compared with the changes in urinary excretion of estradiol metabolites. Alterations of excretion were registered for isoflavonoids, lignans and coumestans. However, due to large variations statistical significant differences were found only for two lignans, i.e. significant increases of enterodiol and matairesinol. Since the single components of phytoestrogens showed diverse alterations, excretions were expressed also by the ratio of total isoflavonoids to total lignans and compared with the estrogen ratios 2-hydroxyestrone to 16alpha-hydroxyestrone and A-ring to D-ring metabolites. The ratio of isoflavonoids to lignans was consistently decreased, whereas both ratios of estradiol metabolites were highly increased. The latter effect is probably due to demethylation of 2-methoxyestrone resulting in high catechol estrogen levels in urine. These results suggest that the high levels of catechol estrogens, produced by 2-MeE2 treatment, may have influenced the urinary excretion pattern of phytoestrogens.

Radioprotective action of curcumin extracted from Curcuma longa LINN: inhibitory effect on formation of urinary 8-hydroxy-2'-deoxyguanosine, tumorigenesis, but not mortality, induced by gamma-ray irradiation.

PURPOSE: We evaluated the radioprotective action of curcumin [1,7-bis(4-hydroxy-3-methoxyphenyl)-1,6-heptadiene-3,5-dione] extracted from Curcuma longa LINN against the acute and chronic effects and the mortality induced by exposure to radiation using female rats. METHODS AND MATERIALS: For the assay of 8-hydroxy-2'-deoxyguanosine (8-OHdG) in urine, a marker for acute effects, Wistar-MS virgin rats were fed the basal diet with exposure at 0 or 3 Gy to gamma-rays from a 60Co source as the control. Rats in the experimental groups received whole-body irradiation with 3 Gy and were fed a diet containing 1% (wt/wt) curcumin for 3 days before and/or 2 days after irradiation. The urine was collected for a 24-h period between 1 and 2 days after irradiation. Urine samples were used to determine the 8-OHdG level using an enzyme-linked immunosorbent assay and the creatinine level by a modified Jaffé reaction. For long-term effects, rats at Day 17 of pregnancy were fed a diet containing curcumin for 3 days before and/or 3 days after irradiation with 1.5 Gy, and received a pellet of diethylstilbestrol as the promoter. The rats were examined for mammary and pituitary tumors for 1 year. To determine survival, virgin rats received whole-body irradiation with 9.6 Gy and were fed a diet containing curcumin for 3 days before and/or 3 days after irradiation. After irradiation, all rats were assessed daily for survival for 30 days. RESULTS: Acutely in virgin rats irradiated with 3 Gy, the creatinine-corrected concentration and total amount of 8-OHdG in the 24-h urine samples were higher (approximately 1.3-fold) than the corresponding values in the nonirradiated controls. Adding curcumin to the diet for 3 days before and/or 2 days after irradiation reduced the elevated 8-OHdG levels by 50-70%. The evaluation of the protective action of curcumin against the long-term effects revealed that curcumin significantly decreased the incidence of mammary and pituitary tumors. However, the experiments on survival revealed that curcumin was not effective when administered for 3 days before and/or 3 days after irradiation (9.6 Gy). CONCLUSION: These findings demonstrate that curcumin can be used as an effective radioprotective agent to inhibit acute and chronic effects, but not mortality, after irradiation.

Seasonal rhythms of 6-sulphatoxymelatonin (aMT6s) excretion in female rats are abolished by growth of malignant tumors.

The effect of development and growth of malignant tumors on pineal melatonin production was studied in two different hormone-dependent tumor systems in female rats. Urinary excretion of 6-sulphatoxymelatonin (aMT6s), the metabolic end product of melatonin, which parallels its production, was determined by radioimmunoassay at fortnightly or monthly intervals over the period of 1 year in female F344 Fischer rats bearing chemically-induced mammary carcinomas and in BDII/Han rats with spontaneous endometrial carcinomas. Untreated Fischer rats and BDII/Han rats in which tumor growth was suppressed by treatment with a progestin served as controls. Based on the cosinor analysis, animals without tumors showed significant seasonal rhythms of aMT6s excretion, with peaks in August (Fischer rats) and in May (BDII/Han rats). In contrast, such rhythms were absent in animals with developing and manifest tumors. It is concluded that animals kept under constant environmental conditions still show seasonal rhythms of pineal activity. Tumor development and growth affect pineal activity leading to disturbance of these rhythms.

Effect of intact and isoflavone-depleted soy protein on NMU-induced rat mammary tumorigenesis.

Experiments in animal models of carcinogenesis suggest that soy consumption decreases tumor number and incidence. Genistein, an isoflavone which is present in soy at high concentrations, has been considered to be the primary antitumor constituent in soy. In the present study, the N-nitroso-N-methylurea (NMU)-induced mammary tumor model was used as a means to determine whether the chemopreventive effect of soy was attributable specifically to its high content of isoflavones. Five groups of rats (30/group) were fed the following modified AIN-93G diets: group 1, 20% intact soy protein (SP); group 2, 10% SP; group 3, 20% isoflavone-depleted soy protein (IDSP); group 4, 10% IDSP; group 5, the casein-based AIN-93G diet. The SP contained 1.07 and IDSP 0.073 mg genistein/g isolate, respectively. Experimental diets were initiated 1 week prior to NMU administration (at 50 days of age) and continued for another 18 weeks. No significant differences were found among the five groups when assessed in terms of tumor incidence, latency, multiplicity or volume. A trend towards inhibition was observed in both the 20 and 10% SP and IDSP groups when assessed in terms of total tumors/group, tumor volume and latency, but this trend did not achieve statistical significance. The results of this model study do not support the hypothesis that the isoflavone components of soy protein, or soy protein itself, inhibit chemically induced mammary tumor development.

Serial transplants of DMBA-induced mammary tumors in Fischer rats as a model system for human breast cancer. VI. The role of different forms of tumor-associated stress for the regulation of pineal melatonin secretion.

Previous studies on human breast cancer patients showed a decline in circulating melatonin levels corresponding to primary tumor growth and an increase when relapse occurred. The aim of the current investigation was to study in an experimental model possible mechanisms involved. Inbred female F344 Fischer rats were used for serial passages derived from a chemically induced mammary adenocarcinoma. Animals with slow-growing carcinosarcomas at passage 2 showed a significant elevation of nocturnal urinary melatonin (23. 00-07.00 h; +50%, p < 0.05) and a nominal increase in plasma melatonin (+41%; 02.00-03.00 h). By contrast, these parameters were significantly depressed in animals with fast-growing sarcomas (urinary melatonin: -22%, p < 0.025; plasma melatonin: -56%, p < 0. 01). At passage 2 nocturnal pineal N-acetylserotonin (02.00-03.00 h) was significantly enhanced (+62%, p < 0.05) probably due to an increased activity of serotonin-N-acetyltransferase (SNAT, +45%), the rate-limiting step of pineal melatonin biosynthesis converting serotonin to N-acetylserotonin. The activation of SNAT may be due to a stimulation of the sympathetic nervous system (urinary noradrenaline; NA: +243%, p < 0.005) when the cellular immune system responded towards tumor growth (urinary biopterin, +214%, p < 0.005). At passage 12 SNAT and N-acetylserotonin were unaffected but a depletion of plasma tryptophan (-34%, p < 0.0001), the precursor amino acid of melatonin, was found. The marginal decline in pineal serotonin (-18%, p < 0.05) disputes that the drastic depletion in circulating melatonin (-56%, p < 0.01) can be exclusively explained by a reduced availability of tryptophan. Therefore, the involvement of an additional mechanism has to be postulated, such as a degradation of melatonin via indoleamine 2,3-dioxygenase, an extrahepatic enzyme which has been detected in tumor tissue and is related to tryptophan 2,3-dioxygenase (TDO). TDO occurs only in the liver, is highly specific for L-tryptophan and is induced by glucocorticoids which would account for the observed depletion of plasma tryptophan resulting from a tumor-associated activation of the hypothalamo-pituitary-adrenal axis (urinary corticosterone +208%, p < 0.01). These findings present first explanations for the previously observed modulation of melatonin levels in cancer patients but also illustrate the high degree of complexity of mechanisms involved in the interactions between tumor growth and the immunoneuroendocrine system.

Inhibition by whole-body hyperthermia with far-infrared rays of the growth of spontaneous mammary tumours in mice.

To evaluate possible therapeutic benefits of irradiation with far-infrared rays (FIR) on breast cancer, we examined combined effects of the chronic exposure to FIR at ambient temperature (26.5-27.5 degrees C) and the whole-body hyperthermia induced by FIR (WBH) (35-41 degrees C) on the growth of spontaneous mammary tumours of mice. A high mammary tumour strain of SHN virgin mice born on the normal rack or FIR rack were maintained on the respective racks until mammary tumour appearance. When the mammary tumour size reached approximately 7 mm, some mice in each group received no further treatment (Control and FIR groups, respectively) and the remaining mice received 3 hours of WBH each of 5 consecutive days (C + WBH and FIR + WBH groups, respectively). There was little difference between the control and FIR groups in the tumour growth over 10 days of examination. On the other hand, the tumour growth was inhibited significantly in both C + WBH and FIR + WBH groups and the degree of inhibition was similar. The data confirmed that the chronic exposure to FIR at ambient temperature has little effect on the growth of spontaneous mammary tumours in mice. WBH with FIR, however, strongly inhibited the tumour growth without deleterious side-effects, while chronic FIR irradiation itself again had little effect in this process. This WBH regimen may serve as a useful animal model for long-term studies of a noninvasive treatment of breast cancer.

Effects of simultaneous treatment with hydroxyapatite and coffee cherry, the residue left after the removal of coffee beans, on spontaneous mammary tumourigenesis and related parameters in SHN mice.

We have found that the chronic administration of the diet containing 5% hydroxyapatite (HAP) derived from bovine or swine bone or drinking water containing 0.5% extract of coffee cherry (CC), the residue left after the removal of coffee beans, induced a marked inhibition of spontaneous mammary tumourigenesis in SHN mice, while the effects decreased with age. In the present study, the combined effects of HAP and CC on mammary tumourigenesis and related parameters were examined. The inhibitory effects of HAP or CC alone on the development and/or the growth of mammary tumours were reduced by HAP + CC. Decreased food and water intake and retarded body growth caused by CC were ameliorated by HAP. Enhancement by HAP or CC of the excretion of the urine components was mostly nullified by HAP + CC. Parameters such as normal mammary gland growth and uterine adenomyosis on which neither HAP nor CC had an effect also did not respond to HAP + CC. These findings suggest that the target is important when administering natural products in combination if the agents are to manifest their effects, additive, synergistic, antagonistic or otherwise.

Flaxseed and its lignan and oil components reduce mammary tumor growth at a late stage of carcinogenesis.

Flaxseed, a rich source of mammalian lignan precursor secoisolariciresinol-diglycoside (S.D.) and alpha-linolenic acid (ALA), has been shown to be protective at the early promotion stage of carcinogenesis. The objective of this study was to determine whether supplementation with flaxseed, its lignan or oil fractions, beginning 13 weeks after carcinogen administration, would reduce the size of established mammary tumors (present at the start of treatment) and appearance of new tumors in rats. Dietary groups consisted of the basal diet (BD, 20% corn oil) alone or supplemented with a gavage of 2200 nmol/day S.D. [S.D., equal to level in 5% flaxseed (F)], 1.82% flaxseed oil (OIL, equal to level in 5% F) or 2.5% or 5% flaxseed (2.5% F and 5% F, respectively). After 7 weeks of treatment, established tumor volume was over 50% smaller in all treatment groups (OIL, 2.5% F, 5% F, P < 0.04; S.D., P < 0.08) while there was no change in the BD group. New tumor number and volume were lowest in the S.D. (P < 0.02) and 2.5% F (P < 0.07) groups. The combined established and new tumor volumes were smaller for the S.D., 2.5% F and 5% F groups (P < 0.02) compared to the OIL and BD groups. The high negative correlation (r = -0.997, P < 0.001) between established tumor volume and urinary mammalian lignan excretion in the BD, S.D., 2.5% F and 5% F groups indicates that the reduction in tumor size is due in part to the lignans derived from the S.D. in flaxseed. However, there was no relationship between new or total tumor development and urinary lignan levels. The effect of flaxseed oil may be related to its high ALA content. In conclusion, the S.D. in flaxseed appears to be beneficial throughout the promotional phase of carcinogenesis whereas the oil component is more effective at the stage when tumors have already been established.

Comparison of mammary gland growth and some physiological parameters in a high mammary tumor strain of SHN mice and ICR, most popular and 'normal' mice.

As a possible step in examining the difference between pathological models and most popular and 'normal' models, the mammary gland and some parameters were compared in SHN mice, a high mammary tumor strain, and ICR mice. SHN was lower than ICR in almost all urinary component levels as indicators of general metabolic activity in both the female and the male, and glucose tolerance in the female. Body weight and several organ weights including liver and kidneys were lower in SHN than in ICR. Normal and preneoplastic mammary gland growth and TGF alpha mRNA expression in the glands of the female were much higher in SHN than in ICR. These findings stress the importance of having a right knowledge of the parameters of 'normal' animals, especially for researchers using pathological models.

Serial transplants of DMBA-induced mammary tumors in Fischer rats as model system for human breast cancer. IV. Parallel changes of biopterin and melatonin indicate interactions between the pineal gland and cellular immunity in malignancy.

Nocturnal (23.00-07.00 h) urinary melatonin and total biopterin (tBI; after acidic oxidation of reduced biopterins) were analyzed during the growth of two passages of a mammary tumor line in female F344 Fischer rats. In addition, nocturnal (02.00-03.00 h) peak concentrations of pineal melatonin in plasma were analyzed when tumors had reached comparable average tumor volumes of 25-30 cm3. Since tetrahydrobiopterin (BH4) is produced by murine macrophages in response to interferon-gamma released by activated T lymphocytes, measurements of tBI can serve to estimate the state of cellular immunity. At passage 2, a slow-growing localized carcinosarcoma, tBI showed a progressing increase during tumor growth reaching more than 200% (p < 0.05-0.005) of controls by the end of the experiment. Urinary and plasma melatonin were elevated by 30-50% (p < 0.05) and 42% respectively. At passage 12, a fast-growing metastasizing sarcoma, a depression of about 20-30% was found for tBI (p < 0.05) and urinary melatonin (p < 0.025); plasma melatonin was depleted by 70% (p < 0.005). Parallel changes of both parameters at each tumor passage indicate a close link between the pineal hormone melatonin and cellular immunity. The opposite trends observed at the two passages indicate a clear stimulation of the immune system and the pineal gland at early but inhibition at advanced stages of cancer.

Determination of estrogen 3-sulfates in biological fluids of mammary tumor-bearing rats by radioimmunoassay.

Determination of estradiol 3-sulfate (E2 3-S) and estriol 3-sulfate (E3 3-S) in plasma, urine or tumor tissues of mammary tumor-bearing rats were performed using the superior radioimmunoassay (RIA) system. The plasma level of E2 3-S after tumorigenesis was found to be about one-third of the normal level. As to E3 3-S, the levels in urine were significantly high both before and after tumorigenesis. Before that, the average level was about 1.5 times, and after that, about 2.5 times as high as the normal level. In tumor tissues, an extremely high level of E3 3-S (399.6 +/- 113.9 pg/g tissue) was determined.

1H-NMR spectroscopy of urinary components of SHN mice in the course of spontaneous mammary tumourigenesis.

Proton nuclear magnetic resonance (1H-NMR) spectroscopy of urine was studied before and after the development of spontaneous mammary tumours in SHN mice. Urinary allantoin and lactic acid levels declined from 2 weeks before mammary tumour appearance and increased with the tumour growth after its appearance. The level of component at 3.4 ppm, which reacted with Ninhydrin and was possibly assigned to taurine, continued to decline beginning 2 weeks before tumour appearance. No considerable changes were observed in urinary levels of creatine and creatinine before and after tumour development, however, these components as well as allantoin or lactic acid had positive correlations with mammary tumour size. A negative correlation was observed between the level of 3.4 ppm component and tumour size. Surgical removal of tumours resulted in an apparent decline in urinary levels of allantoin and lactic acid. At all stages, urinary allantoin level was approximately 4 times as high as the levels of lactic acid and 3.4 ppm component. All results suggest that urinary allantoin would be a good indicator for the development of spontaneous mammary tumours of mice.

Effect of indomethacin treatment on prostaglandin excretion and tissue phospholipid fatty acid composition in rats bearing mammotropic pituitary tumor, MtT-F4.

The hypothesis that hormonal changes induced by the mammotropic pituitary tumor, MtT-F4, might accelerate the conversion of n-6 fatty acids to prostaglandins, resulting in a partial depletion of n-6 fatty acids was examined. In tumor-bearing rats, the administration of indomethacin induced a 50% reduction of the urinary prostaglandin levels, but exerted no significant effect on the fatty acid composition of the tissue phospholipids. It is concluded that the observed depletion of n-6 fatty acids in tumor-bearing rats is not caused by an increased production of prostaglandins.

The effect of C3H mouse mammary tumour on the levels of serum and urine analytes in vivo.

A study of C3H mice implanted with mammary tumours has shown that the levels of serum total protein, alanine transaminase and alkaline phosphatase are all lower than those found in normal mice, while aspartate transaminase is higher. Serum urea values were similar to normal levels, but creatinine was lower in males and higher in females. In the male mice, urine protein and urine N-acetyl-beta-D-glucosaminidase (NAG) activity were lower than in normal mice. Comparisons were made with age and sex matched controls which was found to be important for alkaline phosphatase, as this was shown to decrease with increasing age of the mice over the period from 10-30 weeks of age. The analyte values found in this study provide useful base-line data for assessing biochemical toxicity of cancer chemotherapy agents. It has been shown that some of these values can vary with age, or can be different if tumour-bearing mice are used instead of normal mice.

The effect of ovariectomy on excretion of urinary steroids and tumor growth in rats bearing 7,12-dimethylbenz[a]anthracene-induced mammary cancer.

The relation between the excretion of urinary steroids and the therapeutic effect of ovariectomy on tumors was investigated in female Sprague-Dawley rats bearing 7,12-dimethylbenz[a]anthracene-induced mammary cancer. Ovariectomy significantly reduced the excretion of urinary androgen, 11-deoxy-17-oxosteroid (11-DOOS), but hardly affected that of urinary corticosteroid, 17-deoxy-corticosteroid (17-DOCS). The responsiveness of tumors to ovariectomy was positively correlated with both pre-operative 11-DOOS and pre-operative ratio of 11-DOOS to 17-DOCS, and negatively correlated with pre-operative 17-DOCS. The extent of tumor regression after ovariectomy was associated with the decrease of urinary androgen. A similar correlation was observed between the decrease in the ratio 11-DOOS/17-DOCS and tumor suppression during cyclophosphamide treatment (medical ovariectomy). These results indicated that the tumor response to ovariectomy was related to a shift of the endogenous hormone balance from a relative dominance of androgen to relative dominance of corticosteroid. The significance of the hormonal findings is discussed in the light of the steroid metabolism in human breast cancer.