Epidemiology. Search for a killer: focus shifts from fat to hormones

Heparanase: Cloning, Function and Regulation

In 2019, we mark the 20th anniversary of the cloning of the human heparanase gene. Heparanase remains the only known enzyme to cleave heparan sulfate, which is an abundant component of the extracellular matrix. Thus, elucidating the mechanisms underlying heparanase expression and activity is critical to understanding its role in healthy and pathological settings. This chapter provides a historical account of the race to clone the human heparanase gene, describes the intracellular and extracellular function of the enzyme, and explores the various mechanisms regulating heparanase expression and activity at the gene, transcript, and protein level.

Breast cancer in black African women: a changing situation

Black African women in rural South Africa have a very low incidence rate of breast cancer, 5-10 per 100,000. The rate, however, is rising in the considerably increasing urban population. During the period 1994 to 1999 in Durban, enquiries revealed an average of 57 urban patients admitted to hospital each year, from a population of about 600,000 African women, indicating an age-adjusted annual incidence rate of 15.1 per 100,000. This incidence rate is very low in comparison with those in developed populations, which range from 40 to 89 per 100,000.

In the African patients studied, the mean age on admission was relatively young, 54.1±10.9 years, almost a decade earlier than patients of developed populations. Moreover, the disease was very far advanced; 21.1% were at Stage III and 63.1% at Stage IV. As to exposure to risk factors, African women in general are characterised by certain protective factors. These factors, which closely resemble those of importance in patients in developed populations are, late menarche, early age at birth of first child, high parity (with usually prolonged lactation), and being physically active. However, with ongoing changes in the lifestyle of urban African women, the protective factors are decreasing in their intensity. Changes in these respects have been associated with rises in the disease’s incidence rate. Clearly, because of the late stage of the disease at the time of the patients’ admission to hospital, and hence their poor survival rate, intensive efforts should be made to educate women to seek help at an early stage of their disease. For its avoidance, feasible protective or restraining measures are primarily to adopt a ‘prudent’ lifestyle, in respect of both dietary and non-dietary components. However, the chances of these measures being meaningfully adopted in African urban communities, unfortunately, are negligible. In consequence, further increases in incidence rate would seem inevitable.

The Expression of Lung Resistance Protein in Saliva: A Novel Prognostic Indicator Protein for Carcinoma of the Breast

Considering that saliva is a fluid inundated with proteins, it is possible that solubilized oncogenic proteins may be present in saliva and may be useful in differentiating between healthy and diseased individuals. As a consequence, the purpose of this study was to determine if the solubilized form of LRP was present in stimulated whole saliva and could differentiate between 16 healthy women and 16 women with confirmed Stage I breast cancer. LRP levels were determined using gel electrophoresis and Western blot technology. The results showed LRP at significantly higher concentrations among breast cancer subjects as compared to healthy women.

The human breast and the ancestral reproductive cycle : A preliminary inquiry into breast cancer etiology

This paper, using modern Darwinian theory, proposes an explanation for the increasingly high incidence of breast cancer found among pre-and post-menopausal women living today in westernized countries. A number of factors have been said to be responsible: genetic inheritance (BRCA-1), diet (specifically the increased consumption of dietary fat), exposure to carcinogenic agents, lifetime menstrual activity, and reproductive factors. The primary aim of this paper is to demonstrate the value of a perspective based on Darwinian theory. In this paper, Darwinian theory is used to explore the possibility that the increased incidence of breast cancer is due primarily to the failure to complete in a timely manner the reproductive developmental cycle, beginning at menarche and continuing through a series of pregnancies and lactation. On the basis of comparative data, we assume that most women in ancestral populations began having children before age 20 or so and tended to remain either pregnant or nursing for most of their adult lives. If a woman did not have a child by age 25 or so, she probably would never have one. Therefore, selection would probably not have acted against deleterious traits, such as cancer, that appeared after that age, just as it does not act against such traits in old age.

Synergistic anticancer effects of combined γ-tocotrienol with statin or receptor tyrosine kinase inhibitor treatment

Systemic chemotherapy is the only current method of treatment that provides some chance for long-term survival in patients with advanced or metastatic cancer. γ-Tocotrienol is a natural form of vitamin E found in high concentrations in palm oil and displays potent anticancer effects, but limited absorption and transport of by the body has made it difficult to obtain and sustain therapeutic levels in the blood and target tissues. Statins are inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A (HMGCoA) reductase and are an example of a promising cancer chemotherapeutic agent whose clinical usefulness has been limited due to high-dose toxicity. Similarly, erlotinib and gefitinib are anticancer agents that inhibit the activation of individual HER/ErbB receptor subtypes, but have shown limited clinical success because of heterodimerization between different EGF receptor family members that can rescue cancer cells from agents directed against a single receptor subtype. Recent studies have investigated the anticancer effectiveness of low-dose treatment of various statins or EGF receptor inhibitors alone and in combination with γ-tocotrienol on highly malignant +SA mouse mammary epithelial cells in vitro. Combined treatment with subeffective doses of γ-tocotrienol with these other chemotherapeutic agents resulted in a synergistic inhibition of +SA cell growth and viability. These findings strongly suggest that combined treatment of γ-tocotrienol with other anticancer agents may not only provide an enhanced therapeutic response but also provide a means to avoid the toxicity, low bioavailability, or limited therapeutic action associated with high-dose monotherapy.

EBAG9 inducing hyporesponsiveness of T cells promotes tumor growth and metastasis in 4T1 murine mammary carcinoma

The estrogen receptor-binding fragment-associated gene 9 (EBAG9) has been identified as an estrogen-responsive gene and was recently identified as a tumor-promoting and prognostic factor for renal cell carcinoma. We investigated whether EBAG9 expression was correlated with primary tumor growth and distant tumor metastasis in a murine breast carcinoma model. Knockdown expression of EBAG9 by small interfering RNA significantly suppressed tumor growth and metastasis in vivo in a highly malignant, spontaneously metastasizing 4T1 mouse mammary carcinoma model. 4T1 cells stably overexpressing EBAG9 developed larger and faster tumor growth and lung metastasis compared with parental 4T1 or 4T1 expressing vector alone. Strong specific cytotoxic T lymphocyte activity and enhanced gamma-interferon and interleukin-2 productions were induced in mice that received EBAG9 small interfering RNA therapy. Gene silencing of EBAG9 prolonged the survival of tumor-bearing mice and induced more intensive infiltration of CD8+ T cells in tumor mass. EBAG9 induced apoptosis of T cells, enhanced glycogen synthase kinase 3beta phosphorylation and inhibited gamma-interferon production of T cells when T lymphocytes were cocultured with 4T1 cells overexpressing EBAG9. Furthermore, overexpression of EBAG9 in 4T1 cells was accompanied with enhanced expression of chemokine (C-X-C motif) receptor 4, which might be involved in tumor metastasis. Taken together, our results suggested that EBAG9 promoted primary 4T1 mammary carcinoma growth and distant metastasis, and EBAG9 small interfering RNA exerted overt regression of tumor growth and metastasis. These findings might provide insights into the mechanism through which tumors evade immunosurveillance and provide a strategy for therapeutic intervention of cancer metastases.

Lactoperoxidase folding and catalysis relies on the stabilization of the α-helix rich core domain: A thermal unfolding study

Lactoperoxidase (LPO) belongs to the mammalian peroxidase family and catalyzes the oxidation of halides, pseudo-halides and a number of aromatic substrates at the expense of hydrogen peroxide. Despite the complex physiological role of LPO and its potential involvement in carcinogenic mechanisms, cystic fibrosis and inflammatory processes, little is known on the folding and structural stability of this protein. We have undertaken an investigation of the conformational dynamics and catalytic properties of LPO during thermal unfolding, using complementary biophysical techniques (differential scanning calorimetry, electron spin resonance, optical absorption, fluorescence and circular dichroism spectroscopies) together with biological activity assays. LPO is a particularly stable protein, capable of maintaining catalysis and structural integrity up to a high temperature, undergoing irreversible unfolding at 70 degrees C. We have observed that the first stages of the thermal denaturation involve a minor conformational change occurring at 40 degrees C, possibly at the level of the protein beta-sheets, which nevertheless does not result in an unfolding transition. Only at higher temperature, the protein hydrophobic core, which is rich in alpha-helices, unfolds with concomitant disruption of the catalytic heme pocket and activity loss. Evidences concerning the stabilizing role of the disulfide bridges and the covalently bound heme cofactor are shown and discussed in the context of understanding the structural stability determinants in a relatively large protein.

Early maturation of gonadotropin-releasing hormone secretion and sexual precocity after exposure of infant female rats to estradiol or dichlorodiphenyltrichloroethane

An increase in the frequency of pulsatile gonadotropin-releasing hormone (GnRH) secretion in vitro and a reduction in LH response to GnRH in vivo characterize hypothalamic-pituitary maturation before puberty in the female rat. In girls migrating for international adoption, sexual precocity is frequent and could implicate former exposure to the insecticide dichlorodiphenyltrichloroethane (DDT), since a long-lasting DDT derivative has been detected in the serum of such children. We aimed at studying the effects of early transient exposure to estradiol (E(2)) or DDT in vitro and in vivo in the infantile female rat. Using a static incubation system of hypothalamic explants from 15-day-old female rats, a concentration- and time-dependent reduction in GnRH interpulse interval (IPI) was seen during incubation with E(2) and DDT isomers. These effects were prevented by antagonists of alpha-amino-3-hydroxy-5-methylisoxazole-4 propionic acid (AMPA)/kainate receptors and estrogen receptor. Also, o,p'-DDT effects were prevented by an antagonist of the aryl hydrocarbon orphan dioxin receptor (AHR). After subcutaneous injections of E(2) or o,p'-DDT between Postnatal Days (PNDs) 6 and 10, a decreased GnRH IPI was observed on PND 15 as an ex vivo effect. After DDT administration, serum LH levels in response to GnRH were not different from controls on PND 15, whereas they tended to be lower on PND 22. Subsequently, early vaginal opening (VO) and first estrus were observed together with a premature age-related decrease in LH response to GnRH. After prolonged exposure to E(2) between PNDs 6 and 40, VO occurred at an earlier age, but first estrus was delayed. We conclude that a transient exposure to E(2) or o,p'-DDT in early postnatal life is followed by early maturation of pulsatile GnRH secretion and, subsequently, early developmental reduction of LH response to GnRH that are possible mechanisms of the subsequent sexual precocity. The early maturation of pulsatile GnRH secretion could involve effects mediated through estrogen receptor and/or AHR as well as AMPA/kainate subtype of glutamate receptors.

Promoting effects of milk on the development of 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumors in rats

To assess the effect of milk on the development of 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumors, 48 female Sprague-Dawley rats treated with DMBA were divided into 3 groups and given 1 of 3 test solutions for 20 weeks as their drinking liquid: milk, estrone sulfate solution or tap water. The milk group showed a significantly great incidence (75%) in tumor development compared with the water group (38%) and was comparable to the estrone sulfate group (69%). Mean tumor number per rat in the milk group was significantly higher than that in the water group (p=0.009). We classified the mammary tumors into three histological types: intraductal papilloma, fibroadenoma, and adenocarcinoma. Although the percent of intraductal papilloma and fibroadenoma was almost same among the three groups, malignant tumor was found only in the milk and estrone sulfate groups. In conclusion, our results indicate that milk as well as estrone sulfate promotes the development of DMBA-induced mammary tumors in rat and could be associated with the occurrence of adenocarcinoma.

Organochloride Pesticides in Macedonian Girls With Premature Sexual Development

Premature sexual development (PSD) in girls describes the appearance of secondary sexual signs before the age of 8 years. Early puberty is diagnosed if pubertal signs appear between the age of 8 and 9 years. We found a positive association between the levels of organochloride pesticides (p,p'-DDE) in precocious puberty in girls adopted from developing countries and significantly higher levels than in native Belgian girls with the same condition.

We have compared the serum levels of eight p,p'- DDE in 56 Macedonian girls with PSD and a control group of 24 normal, age-matched girls, using a gas chromatographic analyzer coupled to a tandem mass spectrometer detector. Of the 56 girls with PSD, 42 had premature thelarche, five had early puberty, and nine had precocious puberty of idiopathic (n = 8) or organic (n = 1) origin. We found traces of p,p'- DDE in nine girls (16%) and negative results in 41 (73%), while the remaining six (10%) had a mean level of 1.17 ± 0.7 μg/L. In the control group, traces were found in one girl (4%) and negative results in 18 (75%), while the remaining five (20%) had a mean level of 1.18 ± 0.6 μg/L. We found elevated levels of lindane in the girls with PSD (mean value 1.2 ± 0.8) and significantly higher levels in the control group (1.4 ± 0.8) (p <0.05). We concluded that Macedonian girls with PSD do not have higher levels of p,p'-DDE in their serum than the normal controls. However, the elevated levels of lindane in this population should be further investigated.

Mice expressing myrAKT1 in the mammary gland develop carcinogen-induced ER-positive mammary tumors that mimic human breast cancer

AKT1/PKB is a serine/threonine protein kinase that regulates biological processes such as proliferation, apoptosis and growth in a variety of cell types. To assess the oncogenic capability of an activated form of AKT in vivo we have generated several transgenic mouse lines that overexpress in the mammary epithelium the murine Akt1 gene modified with a myristoylation signal, which renders active this protein by localizing it to the plasma membrane. We demonstrate that expression of myristoylated AKT in the mammary glands increases the susceptibility of these mice to the induction of mammary tumors of epithelial origin by the carcinogen 9,10-dimethyl-1,2 benzanthracene (DMBA). We have found that while carcinogen-treated wild-type mice show mostly mammary tumors of sarcomatous origin, AKT transgenic mice treated with DMBA developed mainly adenocarcinoma or adenosquamous tumors, all of them displaying activated AKT. We analyzed other possible molecular alterations cooperating with AKT and found that neither Ras nor beta-catenin/Wnt pathways seemed altered nor p53 mutated. We have found that 100% of mammary DMBA-induced tumors and benign lesions in myrAKT mice are estrogen receptor (ERalpha)-positive and are more frequent than in wild-type littermates. These data show that AKT activation cooperates with deregulation of the estrogen receptor in the DMBA-induced mammary tumorigenesis model and recapitulate two characteristics of some human breast tumors. Thus, our model might provide a preclinical relevant model system to study the role of AKT and ERalpha in breast tumorigenesis and the response of mammary gland tumors to chemotherapeutics.

Estrogenic regulation of host immunity against an estrogen receptor-negative human breast cancer

PURPOSE

The risk of developing breast cancer is positively correlated with exposure to increased levels of estrogen and/or an increased duration of estrogen exposure. Many different mechanisms have been proposed to explain the association of estrogens with breast cancer risk; however, the well-documented immune modulatory properties of estrogen have received little attention. In part, this is due to a lack of suitable models for studying this relationship.

EXPERIMENTAL DESIGN

We have developed an animal model using estrogen receptor (ER)-negative human breast cancer cell line, MDA-MB-468, xenografted into severe combined immunodeficient (SCID) mice. We also generated the ER-alpha knockout (ER-alphaKO) mice on the SCID background and then tested the ability of 17beta-estradiol to stimulate growth of xenografted ER-negative human breast cancer tumors in wild-type and ER-alphaKO SCID mice. We quantified vascularization of tumors, macrophage recruitment to the tumor site by immunocytochemistry, and inflammatory cytokine production.

RESULTS

We show that estrogen treatment of C57BL/6/SCID mice promotes the growth of xenografted ER-negative tumors in wild-type mice and this estrogen-induced tumor growth is abrogated in ER-alphaKO mice. Tumor neovascularization of estrogen-treated mice was unchanged versus control; however, estrogen treatment of the C57BL/6/SCID host suppressed macrophage recruitment to and inflammatory cytokine production at the tumor site.

CONCLUSIONS

These data are consistent with estrogen modulation of the inflammatory response as a contributing factor in estrogen-stimulated growth of an ER-negative tumor. This effect on the host innate immune response was mediated by ER-alpha.

Female sexual maturation and reproduction after prepubertal exposure to estrogens and endocrine disrupting chemicals: a review of rodent and human data

Natural hormones and some synthetic chemicals spread into our surrounding environment share the capacity to interact with hormone action and metabolism. Exposure to such compounds can cause a variety of developmental and reproductive detrimental abnormalities in wildlife species and, potentially, in human. Many experimental and epidemiological data have reported that exposure of the developing fetus or neonate to environmentally relevant concentrations of some among these endocrine disrupters induces morphological, biochemical and/or physiological disorders in brain and reproductive organs, by interfering with the hormone actions. The impact of such exposures on the hypothalamic-pituitary-gonadal axis and subsequent sexual maturation is the subject of the present review. We will highlight epidemiological human studies and the effects of early exposure during gestational, perinatal or postnatal life in female rodents.

Early onset of puberty: tracking genetic and environmental factors

Under physiological conditions, factors affecting the genetic control of hypothalamic functions are predominant in determining the individual variations in timing of pubertal onset. In pathological conditions, however, these variations can involve different genetic susceptibility and the interaction of environmental factors. The high incidence of precocious puberty in foreign children migrating to Belgium and the detection in their plasma of a long-lasting 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane (DDT) residue suggest the potential role of environmental endocrine disrupting chemicals in the early onset of puberty. This hypothesis was confirmed by experimental data showing that temporary exposure of immature female rats to DDT in vivo results in early onset of puberty. We compared the gene expression profile of hypothalamic hamartoma associated or not with precocious puberty in order to identify gene networks responsible for both hamartoma-dependent sexual precocity and the onset of normal human puberty. In conclusion, pathological variations in the timing of puberty may provide unique information about the interactions of either environmental conditions or genetic susceptibility with the hypothalamic mechanism controlling the onset of sexual maturation, as shown by examples of precocious puberty following exposure to endocrine disrupters or due to hypothalamic hamartoma.

Differential control of growth, cell cycle progression, and expression of NF-κB in human breast cancer cells MCF-7, MCF-10A, and MDA-MB-231 by ponicidin and oridonin, diterpenoids from the chinese herb Rabdosia rubescens

Ponicidin and oridonin are novel diterpenoids isolated from Rabdosia rubescens. We tested their effects in MCF-7 and MDA-MB-231 cells, as representing low and high invasive breast carcinoma, with normal MCF-10A cells. Clonogenicity and proliferation in MCF-7 cells were inhibited more significantly by ponicidin than oridonin, while the reverse was observed in MCF-10A cells. Ponicidin and oridonin induced S/G2M arrest and G1/S block in MCF-7 cells. In MCF-10A cells treated with either diterpenoid, induction of apoptosis was observed. Moreover, oridonin almost completely blocked MCF-10A progression from S to G2/M phase; in contrast, ponicidin-treated MCF-10A cells showed no discernable changes in cell cycle phase distribution. Neither diterpenoid affected growth of MDA-MB-231 cells, at the dose range effective for MCF-7 or MCF-10A cells. Ponicidin-treated MCF-7 cells expressed reduced levels of cyclin B1, cdc2, transcription factor E2F, and Rb including phosphorylation at S780. Less pronounced effects were found in cells treated with oridonin. Neither compound altered cyclin D1 and cdk4 in MCF-7 cells. In MCF-10A cells, oridonin was more active than ponicidin in inhibiting the expression of cyclin B1, cdc2, S780-phosphorylated Rb, and E2F. To further investigate induction of apoptosis in MCF-10A cells, we measured changes in NF-kappaB. Decreases in p65 or p50 forms of NF-kappaB and its upstream regulator I-kappaB were found in oridonin-treated MCF-10A and not MCF-7 cells. Taken together, these results provide a mechanistic framework for the cellular effects of ponicidin and oridonin in different stage breast cancer cells.

Culture and symptom reporting at menopause

The purpose of the present paper is to review recent research on the relationship of culture and menopausal symptoms and propose a biocultural framework that makes use of both biological and cultural parameters in future research. Medline was searched for English-language articles published from 2000 to 2004 using the keyword 'menopause' in the journals--Menopause, Maturitas, Climacteric, Social Science and Medicine, Medical Anthropology Quarterly, Journal of Women's Health, Journal of the American Medical Association, American Journal of Epidemiology, Lancet and British Medical Journal, excluding articles concerning small clinical samples, surgical menopause or HRT. Additionally, references of retrieved articles and reviews were hand-searched. Although a large number of studies and publications exist, methodological differences limit attempts at comparison or systematic review. We outline a theoretical framework in which relevant biological and cultural variables can be operationalized and measured, making it possible for rigorous comparisons in the future. Several studies carried out in Japan, North America and Australia, using similar methodology but different culture/ethnic groups, indicate that differences in symptom reporting are real and highlight the importance of biocultural research. We suggest that both biological variation and cultural differences contribute to the menopausal transition, and that more rigorous data collection is required to elucidate how biology and culture interact in female ageing.

Strategies for managing breast cancer risk after the menopause

Postmenopausal women in Western societies are conscious of breast cancer as a potential cause of death and ill health, which they wish to avoid with the advice of their doctors. Yet many factors that predispose women to the development of cancer will have been laid down before the menopause, in their genetic makeup or during their adolescent years. Even in middle age it is important to take account of the intrinsic level of risk, and to give women advice tailored to their own individual risk level. This results from their family history, previous diseases such as benign breast disease, and previous treatment for breast cancer or Hodgkin's disease. For those at the highest level of risk, strategies will include regular screening, prophylactic mastectomy, and the use of chemoprevention agents, such as tamoxifen. These women should avoid hormone replacement therapy (HRT) and control their menopausal symptoms and osteoporosis through the use of other agents now available - venlafaxine for menopausal symptoms and bisphosphonates for osteoporosis. Raloxifene is an agent under trial that may be valuable for breast cancer control as well as for osteoporosis. Women at standard population risk will require less robust preventive strategies, which will include screening and lifestyle modification. Their decisions regarding HRT should now be modified by recent evidence of associated risks. Recent studies show that tibolone causes less mammographic density and has a lower relative risk of breast cancer than combined estrogen/progestogen preparations. There is limited evidence that controlling obesity, participating in exercise and adopting a diet low in fats and high in fruit and vegetables will alter risk at this age. These precautions will, however, reduce the risk of other diseases common in this age group, such as hypertension, heart disease, stroke, and type 2 diabetes mellitus. Alcohol, even in small amounts, is a risk factor for breast cancer. Given the cardioprotective effect of moderate alcohol intake, advice on alcohol must reflect the individual relative risk of cardiovascular disease and breast cancer. Personal risk assessment is relevant for all women. Screening and a healthy lifestyle are worthwhile approaches for all, with the more aggressive approaches such as chemoprevention and prophylactic surgery reserved for those who have substantially elevated levels of risk. Once the menopause has passed, screening is probably the most effective evidence-based tool for breast cancer control by early diagnosis.

The timing of normal puberty and the age limits of sexual precocity: variations around the world, secular trends, and changes after migration

During the past decade, possible advancement in timing of puberty has been reported in the United States. In addition, early pubertal development and an increased incidence of sexual precocity have been noticed in children, primarily girls, migrating for foreign adoption in several Western European countries. These observations are raising the issues of current differences and secular trends in timing of puberty in relation to ethnic, geographical, and socioeconomic background. None of these factors provide an unequivocal explanation for the earlier onset of puberty seen in the United States. In the formerly deprived migrating children, refeeding and catch-up growth may prime maturation. However, precocious puberty is seen also in some nondeprived migrating children. Attention has been paid to the changing milieu after migration, and recently, the possible role of endocrine- disrupting chemicals from the environment has been considered. These observations urge further study of the onset of puberty as a possible sensitive and early marker of the interactions between environmental conditions and genetic susceptibility that can influence physiological and pathological processes.

Role of GTP-binding proteins in reversing the antiproliferative effects of tocotrienols in preneoplastic mammary epithelial cells

Tocotrienols are a subclass of vitamin E compounds that display potent anticancer activity. Determining the anticancer mechanism of action of tocotrienols will provide essential information necessary for understanding the potential health benefits of these compounds in reducing the risk of breast cancer in women. Epidermal growth factor (EGF) is a potent mitogen for normal and neoplastic mammary epithelial cells. Initial events in EGF-receptor (EGF-R) mitogenic-signalling are G-protein activation, stimulation of adenylyl cyclase and cyclic AMP (cAMP) production. Studies were conducted to determine if the antiproliferative effects of tocotrienols are associated with reduced EGF-induced G-protein and cAMP-dependent mitogenic signalling. Preneoplastic CL-S1 mouse mammary epithelial cells were grown in culture and maintained on serum-free media containing 0-25 micro mol/L tocotrienol-rich fraction of palm oil and/or different doses of pharmacological agents that alter intracellular cAMP levels. Tocotrienol-induced effects on EGF-receptor levels of tyrosine kinase activity, as well as EGF-dependent mitogen-activated pathway kinase (MAPK) and Akt activation, were determined by western blot analysis. Results demonstrate that the antiproliferative effects of tocotrienols in preneoplastic mammary epithelial cells do not reflect a reduction in EGF-receptor mitogenic responsiveness, but rather, result from an inhibition in early post-receptor events involved in cAMP production upstream from EGF-dependent MAPK and phosphoinositide 3-kinase/Akt mitogenic signalling. In summary, these data further characterise the mechanism of action of tocotrienols in suppressing preneoplastic mammary epithelial cell proliferation, and advance the current understanding of the potential health benefits of these compounds in reducing the risk of breast cancer in women.

Progesterone receptors in mammary gland development and tumorigenesis

The steroid hormone, progesterone (P), is a central coordinator of all aspects of female reproductive activity and plays a key role in pregnancy-associated mammary gland morphogenesis and mammary tumorigenesis. The effects of P on the mammary gland are mediated by two structurally and functionally distinct nuclear receptors PR-A and PR-B that arise from a single gene. Null mutation of both receptors in PR knockout (PRKO) mice has demonstrated a critical role for PRs in mediating pregnancy-associated mammary ductal branching and lobuloalveolar differentiation and in initiation of mammary tumors in response to carcinogen. Analysis of the molecular genetic pathways disrupted in PRKO mice has recently yielded important insights into the molecular mechanisms of regulation of mammary gland morphogenesis by PRs. In addition to its essential role in regulating proliferative and differentiative responses of the adult mammary gland during pregnancy, P plays a critical role in the protection against mammary tumorigenesis afforded by early parity. Thus, the effects of P on postnatal developmental plasticity of the mammary gland differ between young and adult glands. This review will summarize recent advances in our understanding of 1) the molecular mechanisms by which PRs mediate pregnancy-associated mammary gland morphogenesis, 2) the role of PRs in mediating tumorigenic responses of the adult mammary gland to carcinogen, and 3) the role of P in long-term protection of the juvenile mammary gland against tumorigenesis. In addition, we will summarize recent insights into the isoform selective contributions to some of these activities of PRs obtained from comparative analysis of P-dependent mammary gland development in PR isoform specific knockout mice lacking either the PR-A (PRAKO) or PR-B (PRBKO).

Cancer of the oesophagus in Africans in sub-Saharan Africa: any hopes for its control?

Oesophageal cancer, a highly lethal tumour, occurs to a variable extent in Africans in sub-Saharan African countries. In many, its incidence remains low, as in the Ivory Coast, Mali and the Gambia. However, in other African countries, the incidence rate has risen considerably, especially in city populations, as in Durban, South Africa, in Kyadondo, Uganda, and in Harare, Zimbabwe, rising to levels far higher than those reported in white populations. As to risk factors, in some African settings, smoking is a factor, and in others, alcohol consumption. Nutritionally, one enquiry, made in Durban, indicated the use of less-refined cereal products, with higher consumptions of vegetables and fruit, to be protective. In developed populations, protective factors are considered to be those characteristic of a "prudent" lifestyle. However, known risk factors largely fail to explain the high variability in the disease's occurrence. In seeking to combat the disease, it is thought unlikely that most Africans, especially urban dwellers, are willing to alter their lifestyle appropriately, even with the understanding that the changes would confer other protective benefits. This suggests that further rises, especially in the contexts of high incidence rates, are inevitable.

With recent changes in environmental factors among Africans in South Africa, how have cancer occurrences been affected?

In South Africa, with changes in environmental factors, varyingly, there have been measures of westernization of diet, with slight rises in intakes of energy and fat, with more of animal, but less of plant foods, being eaten, and with a fall in dietary fibre intake. Smoking practice has increased, particularly in males, likewise alcohol consumption. Physical activity has fallen, especially in urban dwellers. Changes in cancer incidence rates, as reported in the South African Cancer Registry for the periods 1986 and 1993-1995 have been investigated. Additionally, changes in percentages of cancers in hospitals in Johannesburg during 1953-1955 and in Durban during 1994-1996, have been looked into. The high occurrences of oesophageal and cervix cancers have fallen slightly, although more so in respect of liver cancer. But there have been rises, widely varying, in the cases of cancers of the lung, prostate and breast. While some of these changes would be expected from the changes in environmental factors, many cancer occurrence situations remain problematical, e.g. the continuing low occurrence of colorectal cancer. Recently, the rapidly rising epidemic of HIV/AIDS has slightly increased the occurrence of certain cancers, particularly Kaposi's sarcoma and non-Hodgkin's lymphoma. Regarding prevention, chances of cancer control in Africans, through lessening personal risk factors, are very remote, which unfortunately also prevails in large measure in western populations, regarding their reluctance to make the recommended beneficial changes.

Transient suppression of X-ray-induced apoptosis by exposure to power frequency magnetic fields in MCF-7 cells

Epidemiological studies suggest that exposure to power frequency magnetic fields may be a risk factor for breast cancer in humans. To study the relationship between exposure to 60-Hz magnetic fields (MFs) and breast cancer, cell cycle distribution, apoptosis, and the expression of related proteins (p21, Bax, and Bcl-2) were determined in MCF-7 cells following exposure to magnetic fields (60 Hz, 5 mT) alone or in combination with X rays. It was found that exposure of MCF-7 cells to 60-Hz MFs for 4, 8, and 24 h had no effect on cell cycle distribution. Furthermore, 60-Hz MFs failed to affect cell growth arrest and p21 expression induced by X rays (4 Gy). Similarly, 60-Hz MFs did not induce apoptosis or the expression of Bax and Bcl-2, two proteins related to apoptosis. However, exposure of cells to 60-Hz MFs for 24 h after irradiation by X rays (12 Gy) significantly decreased apoptosis and Bax expression but increased Bcl-2 expression. The effects of exposure to 60-Hz MFs on X-ray-induced apoptosis and Bax and Bcl-2 expressions were not observed at 72 h. These data suggest that exposure to 60-Hz MFs has no effects on the growth of MCF-7 cells, but it might transiently suppress X-ray-induced apoptosis through increasing the Bcl-2/Bax ratio.

Sexual precocity after immigration from developing countries to Belgium: evidence of previous exposure to organochlorine pesticides

In a retrospective auxological study of 145 patients seen in Belgium during a 9-year period for treatment of precocious puberty, 28% appeared to be foreign children (39 girls, one boy) who immigrated 4 to 5 years earlier from 22 developing countries, without any link to a particular ethnic or country background. The patients were either adopted (n = 28) or non-adopted (n = 12), the latter having normal weight and height at immigration and starting early puberty without evidence of earlier deprivation. This led to the hypothesis that the mechanism of precocious puberty might involve previous exposure to oestrogenic endocrine disrupters. A toxicological plasma screening for eight pesticides detected p,p'-DDE, which is derived from the organochlorine pesticide DDT. Median p,p'-DDE concentrations were respectively 1.20 and 1.04 ng/ml in foreign adopted (n = 15) and non-adopted (n = 11) girls with precocious puberty, while 13 out of 15 Belgian native girls with idiopathic or organic precocious puberty showed undetectable concentrations (<0.1 ng/ml). A possible relationship between transient exposure to endocrine disrupters and sexual precocity is suggested, and deserves further studies in immigrant children with non-advanced puberty.

Developmental sources of variation in liability to adolescent substance use disorders

This review provides a synthesis of the literature on the complex sequence of maturational, psychosocial, and neuroadaptive processes that lead to substance use disorders (SUD) in adolescence. A brief overview introduces the concepts of liability to SUD and epigenesis. A theory is presented explaining how affective, cognitive, and behavioral dysregulation in late childhood is exacerbated during early and middle adolescence by family and peer factors, as well as puberty, leading to substance use. Continued exacerbation of the three components of dysregulation by drug and non-drug stressors during late adolescence is posited to result in neuroadaptations that increase the likelihood of developing SUD, particularly in high-risk individuals. Implications for etiologic research as well as clinical and preventive interventions are discussed.

N-(n-Benzylpiperidin-4-yl)-2-[18F]fluorobenzamide: a potential ligand for PET imaging of breast cancer

N-(N-Benzylpiperidin-4-yl)-2-[(18)F]fluorobenzamide (2), a potential ligand for PET imaging of sigma receptor, has been found to be a potential agent for detection of breast cancer. In vivo studies in severe combined immunodeficient (SCID) mice bearing MDA-MB231 tumors showed that the uptake of compound 2 in these tumors was high (3.8%/g); the ratios of tumor/muscle and tumor/blood were 6.2 and 7.0, respectively, at 1 h postinjection. Pretreatment of SCID mice with haldol increased the uptake of compound 2 in blood, muscle, and other well-perfused organs while decreasing its uptake in tumors. The ratios of tumor/muscle and tumor/blood decreased from 6.2 and 7.0 to 1.3 and 1.1, respectively, at 1 h postinjection. At 2 h postinjection, the ratios of tumor/muscle and tumor/blood decreased from 4.9 and 7.8 to 1.4 and 1.4, respectively. The tumor uptake of compound 2 in SCID mice bearing primary tumor explants from a human breast cancer patient was lower than that in MDA-MB231 tumors (1.66%/g versus 3.78%/g), and the ratios of tumor/muscle and tumor/blood were 3.5 and 3.7, respectively, at 1 h postinjection. These results suggest that compound 2 may be a potential ligand for PET imaging of breast cancer.

Breast cancer--can risks really be lessened?

Breast cancer, although uncommon in western populations in the past, continues to rise in incidence, and now affects up to one woman in nine. In some countries, such as the US and Australia, the mortality rate is decreasing, albeit slightly. In developing populations, while of low occurrence, the disease is rising in incidence. Risk factors, which include certain reproductive practices, diet and physical activity, while apparent in some contexts, appear much less so in others; moreover, the avoiding measures do not lend themselves to primary prevention. For early detection, although regular mammography is advocated, it is a subject of controversy. Basically, avoiding measures fall within the usual recommendations for a 'prudent' lifestyle - avoid obesity, increase physical activity, stop smoking and restrict alcohol consumption.

Collective fear, individualized risk: the social and cultural context of genetic testing for breast cancer

The purpose of this article is to provide a critical examination of two aspects of culture and biomedicine that have helped to shape the meaning and practice of genetic testing for breast cancer. These are: (1) the cultural construction of fear of breast cancer, which has been fuelled in part by (2) the predominance of a 'risk' paradigm in contemporary biomedicine. The increasing elaboration and delineation of risk factors and risk numbers are in part intended to help women to contend with their fear of breast cancer. However, because there is no known cure or foolproof prevention for breast cancer, risk designations bring with them recommendations for vigilant surveillance strategies and screening guidelines. We argue that these in effect exacerbate women's fears of breast cancer itself. The volatile combination of discourses of fear, risk and surveillance have significant ethical and social consequences for women's lives and well-being. Genetic testing decisions are made within this context; if nurses understand this context they can play an important role in helping women to cope with the anxiety and fear of breast cancer risk.

Optical tomographic image reconstruction from ultrafast time-sliced transmission measurements

Optical imaging and localization of objects inside a highly scattering medium, such as a tumor in the breast, is a challenging problem with many practical applications. Conventional imaging methods generally provide only two-dimensional (2-D) images of limited spatial resolution with little diagnostic ability. Here we present an inversion algorithm that uses time-resolved transillumination measurements in the form of a sequence of picosecond-duration intensity patterns of transmitted ultrashort light pulses to reconstruct three-dimensional (3-D) images of an absorbing object located inside a slab of a highly scattering medium. The experimental arrangement used a 3-mm-diameter collimated beam of 800-nm, 150-fs, 1-kHz repetition rate light pulses from a Ti:sapphire laser and amplifier system to illuminate one side of the slab sample. An ultrafast gated intensified camera system that provides a minimum FWHM gate width of 80 ps recorded the 2-D intensity patterns of the light transmitted through the opposite side of the slab. The gate position was varied in steps of 100 ps over a 5-ns range to obtain a sequence of 2-D transmitted light intensity patterns of both less-scattered and multiple-scattered light for image reconstruction. The inversion algorithm is based on the diffusion approximation of the radiative transfer theory for photon transport in a turbid medium. It uses a Green s function perturbative approach under the Rytov approximation and combines a 2-D matrix inversion with a one-dimensional Fourier-transform inversion to achieve speedy 3-D image reconstruction. In addition to the lateral position, the method provides information about the axial position of the object as well, whereas the 2-D reconstruction methods yield only lateral position.

[Reproductive risk factors associated with breast cancer in Colombian women]

INTRODUCTION

As of 1992, breast cancer has been the second cause of death in Columbian women, with a rising trend in mortality due to this type of neoplasm (average annual rate 4.5*/100.000 inhabitants). Information about potential risk factors for breast cancer in Latin American countries is scarce. The objectives of the project were to test the breastfeeding protection against breast cancer and to establish the reproductive factors associated with breast cancer in Columbia.

METHODS

A hospital case-control study was carried out from July 1995 to March 1996 in Bogotá, Columbia, using paring by age groups. The study population consisted of 171 histopathologically confirmed cases and 171 controls. Reproductive history and sociodemographic data were collected through a questionnaire, and logistic regression models were used for statistical analysis of the data.

RESULTS

The following associated factors were found as principal results: nuli-parousness as compared with women with over 3 children (OR=3.35 CI 1.40-8.0), age at first birth (OR=1.83 CI 0.70- 4.80), breast cancer history, breastfeeding the first child (OR=0.09 CI 0.01-0.64 for 1-11 months) and with a highly significant trend for accumulated breastfeeding above 24 months (p=0.001).

CONCLUSIONS

This study indicates the importance of focusing on the promotion of prolonged breastfeeding by women identified as being at higher risk, and confirms that socio-economic level can determine life styles and reproductive events among women (such as breastfeeding time); this could explain the increase in breast cancer mortality in Latin American countries, similar to that in developed countries in terms of fertility and risk factors for breast cancer. The epidemiological information produced by this study will be useful for planning and carrying out early diagnosis and treatment of breast cancer in women identified as being at high risk of this disease.

Associations between physical activity and susceptibility to cancer: possible mechanisms

Physical activity is associated with a reduced risk of all-cause and colonic cancers, and it seems to exert a weaker effect on the risk of breast, lung and reproductive tract tumours. This review examines possible mechanisms behind the observed associations. Restriction of physical activity by pre-existing disease may contribute to the association with lung cancers, but seems a less likely explanation for other types of tumour. Indirect associations through activity-related differences in body build or susceptibility to trauma seem of minor importance. Potential dietary influences include overall energy balance and energy expenditure, the intake and/or bioavailability of minerals, antioxidant vitamins and fibre, and the relative proportions of protein and fat ingested. Links between regular exercise and other facets of lifestyle that influence cancer risks are not very strong, although endurance athletes are not usually smokers, and regular leisure activity is associated with a high socioeconomic status which tends to reduce exposure to airborne carcinogens, both at work and at home. Overall susceptibility to cancer shows a 'U'-shaped relationship to body mass index (mass/height2) reflecting, in part, the adverse influences of cigarette smoking and a tall body build for those with low body mass indices and, in part, the adverse effect of obesity at the opposite end of the body mass index distribution. Obesity seems a major component in the exercise-cancer relationship, with a particular influence on reproductive tract tumours; it alters the pathways of estradiol metabolism, decreases estradiol binding and facilitates the synthesis of estrogens. Among the hormonal influences on cancer risk, insulin-like growth factors promote tumour development and exercise-mediated increases in cortisol and prostaglandin levels may depress cellular components of immune function. However, the most important change is probably the suppression of the gonadotropic axis. Apparent gender differences in the benefits associated with regular exercise reflect gender differences in the hormonal milieu and also a failure to adapt activity questionnaires to traditional patterns of physical activity in females. The immune system is active at various stages of tumour initiation, growth and metastasis. However, acute and chronic changes in immune response induced by moderate exercise are rather small, and their practical importance remains debatable. At present, the oncologist is confronted by a plethora of interesting hypotheses, and further research is needed to decide which are of practical importance.

The extent of proliferative and apoptotic activity in intraductal and invasive ductal breast carcinomas detected by Ki-67 labeling and terminal deoxynucleotidyl transferase-mediated digoxigenin-11-dUTP nick end labeling

BACKGROUND

The balance among cell proliferation, cell differentiation, and cell death determines the cell number in a population as well as the size or even the stage of a tumor. Thus, to improve our understanding of the pathogenesis of neoplasms, it is important to investigate the regulation of both cell proliferation and cell death.

METHODS

This study examined the occurrence of apoptosis and proliferative capacity in 46 breast carcinomas: 20 intraductal carcinomas (ductal carcinomas in situ [DCIS]) and 26 infiltrative ductal carcinomas (IDC). Terminal deoxynucleotidyl transferase-mediated digoxigenin-11-dUTP nick end labeling (TUNEL) and immunostaining with the Ki-67 antibody were used in the examination. A ladder of DNA fragments induced by apoptosis was demonstrated by means of DNA agarose gel electrophoresis in 10 of the available TUNEL positive and negative samples.

RESULTS

The results were correlated with p53, bcl-2, estrogen receptor (ER), and progesterone receptor (PR) protein expression, which would suggest association with apoptosis by immunohistochemistry. The apoptosis and proliferation of each cancer were expressed as the number of tumor cells undergoing apoptosis and proliferation per 1000 tumor cells. The extent of apoptosis was more frequently observed in DCIS than in IDC (21.9+/-6.8 vs. 4.0+/-0.9, P < 0.001), and the proliferation activity was significantly higher in IDC than in DCIS (16.8+/-6.5 vs. 3.5+/-0.8, P < 0.006). Apoptosis associated with MIB-1 positive cells and TUNEL labeling was significantly higher in IDC than in DCIS (3.26 vs. 0.42, P=0.001). In DCIS, apoptosis was correlated with p53 (r=0.663, P=0.005), and p53 had a reverse correlation with bcl-2 (r=0.620, P= 0.018). Moreover, bcl-2 expression was associated with ER (P=0.028) and PR (P= 0.005) expression in both DCIS and IDC.

CONCLUSIONS

The results of this study show that a higher degree of apoptosis and lower proliferation activity in intraductal carcinoma result in a steady-state, self-renewing condition in which net growth of the tumor is rare. The results also indicate that apoptosis was altered by the expression of p53, bcl-2, ER, and PR.

Xenoestrogens significantly enhance risk for breast cancer during growth and adolescence

Breast cancer is one of the most common forms of cancer observed in women, and endogenous estrogen is thought to play a major role in its development. Because of this, any conditions or exposures which enhance estrogenic responses would result in an increased risk for breast cancer. The role of xenoestrogenic compounds, such as DDT, in the etiology of breast cancer is still very controversial. In the following paper we discuss recently-published observations by ourselves and others which indicate that xenoestrogens may play a significant role in the development of breast cancer. Specifically, we hypothesize that during periods of high growth rates and during breast development the sensitivity of breast cells to estrogenic compounds is sufficiently great for xenoestrogens to significantly enhance risk for breast cancer.

Secondary sexual characteristics and menses in young girls seen in office practice: a study from the Pediatric Research in Office Settings network

OBJECTIVE

To determine the current prevalence and mean ages of onset of pubertal characteristics in young girls seen in pediatric practices in the United States.

METHODS

A cross-sectional study was conducted by 225 clinicians in pediatric practices belonging to Pediatric Research in Office Settings, a practice-based research network. After standardized training in the assessment of pubertal maturation, practitioners rated the level of sexual maturation on girls 3 through 12 years who were undergoing complete physical examinations.

RESULTS

Data were analyzed for 17,077 girls, of whom 9.6% were African-American and 90.4% white. At age 3, 3% of African-American girls and 1% of white girls showed breast and/or pubic hair development, with proportions increasing to 27.2% and 6.7%, respectively, at 7 years of age. At age 8, 48.3% of African-American girls and 14.7% of white girls had begun development. At every age for each characteristic, African-American girls were more advanced than white girls. The mean ages of onset of breast development for African-American and white girls were 8.87 years (SD, 1.93) and 9.96 years (SD, 1.82), respectively; and for pubic hair development, 8.78 years (SD, 2.00) and 10.51 years (SD, 1.67), respectively. Menses occurred at 12.16 years (SD, 1.21) in African-American girls and 12.88 years (SD, 1.20) of age in white girls.

CONCLUSIONS

These data suggest that girls seen in a sample of pediatric practices from across the United States are developing pubertal characteristics at younger ages than currently used norms. Practitioners may need to revise their criteria for referral of girls with precocious puberty, with attention to racial differences.

Proliferating cell nuclear antigen and heat shock protein 70 immunolocalization in invasive ductal breast cancer not otherwise specified

A series of 80 female patients undergoing surgery for primary breast ductal infiltrating carcinoma not otherwise specified (NOS) was immunohistochemically studied in order to verify any relationships between Proliferating Cell Nuclear Antigen (PCNA) immunostaining, Heat Shock Protein 70 (HSP70) immunoreactivity, and several clinicopathological predictors. Positive PCNA scores (> 20% of strongly immunopositive malignant nuclei) were observed in neoplastic cells' nuclei in 13 tumors (16.25%) and were intimately associated with axillary nodal involvement (p = 0.0131), relatively high tumor grades (p = 0.0016), increased tumor size (p = 0.0312), and low or negative levels of estrogen receptors (p = 0.0323). HSP70 positive immunoexpression in malignant cells' cytoplasm (percentage of HSP70 immunoreactive cells > 10%) was detected in 33 samples (41.25%). It correlated significantly with presence of axillary lymph nodal metastases (p = 0.0033) and rather poor tumor differentiation (p = 0.0014), whereas an association of borderline statistical significance emerged between HSP70 immunoreactivity and high progesterone receptor status (p = 0.0637). PCNA positive immunostaining demonstrates the tumors' proliferative fraction and might be used as an indicator of increased malignant potential in breast cancer since it was associated with four adverse prognosticators. HSP70 immunodetection is a probable marker of the biological stress experienced by breast cancer cells, since it was related to relatively high tumor grades. Since both proteins may potentially predict disease outcome, their prognostic significance must be validated by direct relation to survival. A multivariate statistical analysis including the variables with which both proteins were associated will reveal any possible independent prognostic value of PCNA and HSP70 immunostaining in local, ductal invasive breast cancer NOS.

Diet in the prevention of cancer: what are the chances of avoidance?

In most western populations, cancer causes about a fifth of all deaths, and in developing populations, 5-15%, with the likelihood of further rises. Diet is considered responsible for about a third of cases of cancer and smoking another third. Dietarily, for cancer avoidance, recommendations made include eat less, eat much less fat especially saturated fat, and eat more plant foods, i.e. cereals, but very particularly vegetables and fruit. However, only high consumptions of the latter are consistently associated with a lower risk of cancers, notably of the digestive and respiratory tracts. For each change urged, meaningful compliance will be very difficult, due largely to conservativeness as well as to the higher cost of a 'prudent' diet. Notwithstanding, urges to make dietary changes, particularly relating to plant foods, must be continued, especially with regard to persons familially susceptible and, additionally, with the recognition that the measures recommended also serve to lessen susceptibility to cardiovascular diseases. Compliance, even by a small proportion, could result in large numbers benefiting due to the universality of the burden from cancer.

Expression of the estrogen receptor gene in developing and adult human breast

Although studies of the estrogen receptor gene abound in rodent models and breast cancer cell lines, little is known about expression of this gene in normal human breast. Information regarding the physiology of this gene's expression is important if we are to elucidate abnormalities of the gene that may be involved in breast carcinogenesis. We evaluated levels of mRNA expression of the estrogen receptor (ER) gene and its protein product in a set of 89 breasts from clinically normal female infants, children, adolescents, and adult premenopausal and post-menopausal women. mRNA expression of the gene varied with the hormonal status. Relatively higher levels of gene transcripts were found in breasts of peri-menarchal girls, women in the luteal phase of the menstrual cycle, and in those with fibrocystic change. Higher levels were also occasionally found in breasts of infants and in most pre-adolescent children. Lower levels were seen in breasts of women in the follicular phase of the menstrual cycle, during pregnancy, and after menopause. Nuclear protein staining was common in breasts of normal children and peri-menarchal adolescents, and in post-menopausal atrophic breasts. Nuclear ER protein was infrequently detected in reproductive aged women's breasts, but was more often seen in follicular than in luteal menstrual phase or pregnant breast. ER protein was more frequently seen in post-menopausal than in pre-menopausal breasts with fibrocystic change. The results fit a model in which circulating levels of estrogen are inversely related to levels of mRNA transcribed from the estrogen receptor gene in normal physiologic states. Abnormally high levels of gene transcription may occur in some cases of fibrocystic change.

Intratumour amount of sex steroids in elderly breast cancer patients. An approach to the biological characterization of mammary tumours in the elderly

Interest in breast cancer in elderly women is growing as a result of the high frequency of cancer in older age groups. We measured tumour concentrations and circulating levels of testosterone, dihydrotestosterone (DHT) and oestradiol in 50 postmenopausal patients: 26 younger than 70 yr (median, 61.5, range 50-69) and 24 older than 70 yr (median, 74.5, range 70-82). Hormones were measured by radioimmunoassay (RIA) after extraction and separation on celite column chromatography. Intratumour levels of the three steroids were lower in the older than in the younger patients, but the difference was statistically significant only for DHT (P= 0.0126). The decrease in the tumour concentrations of testosterone and DHT in the older group was associated with a slight increase in circulating levels, yielding as final result a statistically significant decrease of the tissue/plasma (T/P) ratio of these hormones. No significant difference was observed between groups for oestradiol levels. The blood levels of testosterone, DHT and oestradiol were significantly correlated in the older group, but not in the younger group. In contrast, the tumour amounts of testosterone and DHT were found to be significantly associated only in the < 70 yr group. We concluded that the hormonal environment in which breast cancer develops is different in younger and older postmenopausal patients, and that the difference mainly concerns the intratumour amounts of androgens, suggesting that the steroids concur in the growth regulation of mammary tumours.