Breast cancer (1)

Who's liable for breast cancer prevention? Your patient can sue--and win--if preventive options aren't made clear

Strategies to reduce the likelihood of breast cancer in high-risk patients present complex medical-legal issues. An accurate and thorough medical history, objective calculation of risk, thorough discussion of preventive options and side effects, meticulous documentation of physician-patient interactions, and meticulous follow-up are essential. These elements form the foundation of a sound approach to breast cancer prevention in high-risk patients and should reduce physician liability if cancer occurs.

BRCA2: a genetic risk factor for breast cancer

The identification of the breast cancer susceptibility genes BRCA1 and BRCA2 a few years ago has been greeted with great excitement and has raised hopes that they might illuminate the common mechanisms of this disease. Today we have to recognize that these expectations remain unfulfilled. Mutations in BRCA1 and BRCA2 account only for a relatively small proportion of breast cancers, even within the group of familiar clusters, they seem to be virtually non-existing in sporadic breast cancers. A substantial proportion of familiar breast cancer clusters has failed to provide evidence for an association with mutations in either BRCA1 or BRCA2, thus we have to look forward to the identification of additional breast cancer susceptibility genes. What has been most disappointing is that the mutation status of BRCA1/2 can provide only limited information for cancer risk. Initial assessments had indicated a risk of close to 90% for mutation carriers to develop breast cancer until age 75 - a value that turned out to be restricted to high-risk families in which the BRCA1 and BRCA2 genes had been genomically mapped. In unselected clusters the risk appears much lower, some estimates suggest less than 40%. Both BRCA1 and BRCA2 large encode proteins that appear to have a plethora of functions, with a conspicuous association to DNA repair and DNA recombination, and probably transcription activation. Defects in DNA repair can result in cancer predisposition syndromes and are recognized as being instrumental in cancer progression. Central questions have remained unanswered: What is the function of damaged BRCA1 and BRCA2 genes in breast cancer risk? What is the basis of large variations of risk conferred to the patients by identical mutations? How can the predictive value of mutation surveys be increased?

Hormone-induced protection against breast cancer

Reproductive history is a consistent risk factor for human breast cancer. Epidemiological studies have repeatedly demonstrated that early age of first full-term pregnancy is a strong protective factor against breast cancer and provides a physiologically operative model to achieve a practical mode of prevention. In rodents, the effects of full-term pregnancy can be mimicked by exposure to low doses of estrogen and progesterone or treatment with human chorionic gonadotropin. The cellular and molecular mechanisms that underlie hormone-induced refractoriness are largely unresolved. Several hypotheses have been proposed to explain the protective effects of hormones. These involve the induction of differentiation of the mammary gland to provide a less responsive cell population to carcinogens, a decrease in proliferative activity in the parous gland compared to the age-matched virgin, an altered hormonal environment mediated by a decrease in circulating growth hormone, and an alteration in cell fate mediated by specific molecular changes induced by estrogen and progesterone. The evidence for and against these hypotheses is discussed along with recent results on possible molecular alterations that may underlie the refractory state. One central question that is still unresolved is whether the refractoriness is intrinsic to the mammary epithelial cells and/or mediated by persistent alterations in the host environment.

Hormonal control of alveolar development and its implications for breast carcinogenesis

During puberty and pregnancy, the breast undergoes major restructuring in order to produce a structure that can secrete and eject copious amounts of milk. By analogy to other branched organs such as the lung or the salivary gland, a large increase in surface area of the specialized epithelium is achieved through repeated ramifications of a system of ducts and alveoli arising from the nipple. In the breast, this process culminates in the appearance of thousands of alveoli or acini, saccular outpouchings from the ductal system. This paper focuses on this final stage of proliferation, the formation of alveolar structures and its control by systemic hormones.

Mechanisms of hormonal prevention of breast cancer

Reproductive history is a consistent risk factor for human breast cancer. Epidemiological studies have repeatedly demonstrated that early age of first pregnancy is a strong protective factor against breast cancer and provides a physiologically operative model to achieve a practical mode of prevention. In rodents, the effects of full-term pregnancy can be mimicked by a three-week exposure to low doses of estrogen and progesterone. Neither hormone alone is sufficient to induce protection. The cellular and molecular mechanisms that underlie hormone-induced refractoriness are largely unresolved. Our recent studies have demonstrated that an early cellular response that is altered in hormone-treated mammary cells is the initial proliferative burst induced by the chemical carcinogen methylnitrosourea. The decrease in proliferation is also accompanied by a decrease in the ability of estrogen receptor-positive cells to proliferate. RNA expression of several mammary cell-cycle-related genes is not altered in hormone-treated mice; however, immunohistochemical assays demonstrate that the protein level and nuclear compartmentalization of the p53 tumor suppressor gene are markedly upregulated as a consequence of hormone treatment. These results support the hypothesis that hormone stimulation, at a critical period in mammary development, results in cells with persistent changes in the intracellular regulatory loops governing proliferation and response to DNA damage. A corollary to this hypothesis is that the genes affected by estrogen and progesterone are independent of alveolar differentiation-specific genes. Suppressive subtractive hybridization-PCR methods have identified several genes that are differentially expressed as a consequence of prior estrogen and progesterone treatment. Future experiments are aimed at determining the mechanisms of hormone-induced upregulation of p53 protein expression as part of the overall goal of identifying and functionally characterizing the genes responsible for the refractory phenotype.

Susceptibility to estrogen-induced mammary cancer segregates as an incompletely dominant phenotype in reciprocal crosses between the ACI and Copenhagen rat strains

Estrogens have been inextricably linked to the etiology of breast cancer. We have demonstrated that the female ACI rat exhibits a unique propensity to develop mammary cancers when treated continuously with physiological levels of 17 beta-estradiol (E2). The E2-induced mammary cancers are estrogen dependent and exhibit genomic instability. In contrast, the genetically related Copenhagen (COP) rat strain is relatively resistant to E2-induced mammary cancers. In this study we evaluated susceptibility to E2-induced mammary cancers in first filial (F(1)), second filial (F(2)), and backcross (BC) progeny generated from reciprocal intercrosses between the ACI and COP strains. F(1) progeny resembled the parental ACI strain with respect to incidence of E2-induced mammary cancers. However, latency was significantly prolonged in the F(1) populations. These data indicate that susceptibility behaves as an incompletely dominant phenotype in these crosses. Analysis of phenotypes exhibited by the F(1), F(2), and BC populations suggests that mammary cancer susceptibility is modified by one or two genetic loci in the reciprocal intercrosses between the ACI and COP strains. Susceptibility to E2-induced mammary cancers did not correlate with E2-induced pituitary growth in the genetically diverse F(2) and BC populations, suggesting that the genetic bases for susceptibility to E2-induced mammary cancers differ from those for E2-induced lactotroph hyperplasia.

Three-dimensional MR imaging of mammographically detected suspicious microcalcifications

BACKGROUND

The purpose of this study was to evaluate the diagnostic value and clinical significance of three-dimensional MR imaging of the breast in patients with mammographically detected suspicious microcalcifications.

METHODS

Forty patients with suspicious microcalcifications on mammography were evaluated with three-dimensional MR imaging. MR findings were grouped mainly by distribution of abnormal enhancement (linear, focal-clumped, segmental-clumped, segmental-stippled and diffuse-stippled). These findings were compared with the mammography findings according to the criteria of the Breast Imaging Reporting and Data System (BI-RADS) and histopathologic data.

RESULTS

Twenty patients had proven malignancies, most frequently ductal carcinoma in situ. For all the cases, linear (100%) and segmental-clumped type (100%) enhancement on MR imaging showed a significantly higher risk for malignancy. Diffuse stippled type (7%) and no enhancement (0%) on MR imaging indicated the lowest possibility of malignancy. 3D-MR imaging showed a sensitivity of 90%, a specificity of 95% and an overall accuracy of 93% in this study.

CONCLUSIONS

Three-dimensional MR imaging of the breast can more accurately diagnose ductal carcinoma in situ. Combined with mammography, this procedure is useful for reducing the number of false-positive biopsies and helpful for deciding the better management of patients with mammographically detected suspicious microcalcifications.

Inhibition of estrogen-dependent breast cell responses with phenylacetate

The aromatic fatty acid phenylacetate (PA) and its analogs have come under intense investigation due to their ability to cause the growth arrest of a variety of neoplasia, including human breast cancer. We have determined that PA and its halide derivative 4-chlorophenylacetate (4-CPA) showed marked antiproliferative activity on 3 of 6 human breast cancer cell lines tested. Interestingly, the 3 cell lines that were growth inhibited by PA and 4-CPA were estrogen receptor (ER) positive (T47-D, MCF-7 and ZR-75-1) whereas those that were little affected by these compounds were ER-negative (MDA-MB-157, MDA-MB-231 and SK-Br-3). Dose response studies indicated that 4-CPA inhibited the growth of the sensitive (ER+) cell lines with a potency 3-4 times that of PA. These findings suggest that there is "cross-talk" between the PA and estrogen signaling pathways such that PA can directly inhibit estrogen-dependent events. This hypothesis was directly tested in vitro using ER+ MCF-7 cells that were stably transfected with a luciferase reporter construct driven by the full length (1745 bp) cyclin D1 promoter (MCF-7-D1). Our experiments with MCF-7-D1 cells indicated that PA and 4-CPA inhibited basal and estrogen-induced reporter gene activity by up to 90%, resulting in almost complete elimination of estrogen-dependent cyclin D1 gene activation. Using a reporter gene construct (ERE(V)-tk-Luc) containing a canonical estrogen response element that was transiently transfected into MCF-7 and MDA-MB-231 cells, we have also demonstrated inhibition of promoter activity by PA and 4-CPA that was directly mediated by blockage of activity through the ERE. Taken together, these findings indicate that PA analogs possess potent antiestrogen properties that may, at least partly, account for their antiproliferative effects on ER+ breast cancer cells. The data suggests a novel mechanism of action that might bypass some of the limitations of conventional antiestrogen therapy.

Catechol-O-Methyltransferase (COMT) gene polymorphism and breast cancer risk in young women

Oestrogen exposure has long been considered to be a main risk factor of breast cancer. More recently, interest has also focused on the possible carcinogenic influence from oestrogen metabolites, such as catechol oestrogens. O-methylation, catalysed by Catechol-O-Methyltransferase (COMT), is one pathway by which the potentially carcinogenic catechol oestrogens can be inactivated. The gene coding for COMT protein contains a single-nucleotide polymorphism (SNP), resulting in an amino acid shift Val-->Met, which has been shown to determine high- and low-activity configuration of the enzyme. We hypothesized that the low-activity allele, COMT(Met), may be implicated in early onset breast cancer. In the present case-control study, including 126 young breast cancer patients (<or= 36 years) and 117 healthy female blood donors, we analysed the association between COMT(Met) genotype and risk of breast cancer. No significant difference in the frequency of low-/high-activity alleles was found between cases and controls, indicating that the polymorphism, as a single factor, may not contribute to breast carcinogenesis in young women.

Short-term exposure to estrogen and progesterone induces partial protection against N-nitroso-N-methylurea-induced mammary tumorigenesis in Wistar--Furth rats

The lifetime protective effect of a full term pregnancy for breast cancer is a reproducible and consistent finding in human beings and in rodent models. The duration of pregnancy necessary to confer protection has yielded contradictory results. As the administration of estrogen and progesterone mimics the full-term pregnancy effect on conferring protection, we examined whether short-term exposure to estrogen and progesterone confers protection against N-nitroso-N-methylurea-induced mammary carcinogenesis in Wistar--Furth rats. The results reported herein show that treatment of rats with estrogen or progesterone alone for 21 days does not confer protection, but a 10-day exposure to the same concentrations of estrogen and progesterone induced a partial protective effect. The significance of these results are discussed in terms of the contradictory results in the literature and the role of morphological differentiation in conferring the protective effect.

A bone-seeking clone exhibits different biological properties from the MDA-MB-231 parental human breast cancer cells and a brain-seeking clone in vivo and in vitro

Breast cancer has a predilection for spreading to bone. The mechanism of preferential metastasis of breast cancer to bone is unknown. We hypothesize that breast cancer cells that develop bone metastases have the capacity to facilitate their colonization in bone. To examine this hypothesis, we established bone-seeking (MDA-231BO) and brain-seeking (MDA-231BR) clones of the human breast cancer cell line MDA-MB-231 by repeated sequential passages in nude mice and in vitro of metastatic cells obtained from bone and brain metastases, respectively. These clones were examined for distinguishing biological characteristics and compared with the MDA-231 parental cells (MDA-231P) in vivo and in vitro. Both the MDA-231BR and the MDA-231BO showed identical tumorigenicity to MDA-231P at the orthotopic site. MDA-231P that was inoculated into the heart developed metastases in bone, brain, ovary, and adrenal glands. On the other hand, MDA-231BO exclusively metastasized to bone with larger osteolytic lesions than MDA-231P. MDA-231BR exclusively disseminated to brain and failed to develop bone metastases. In culture, MDA-231BO produced greater amounts of parathyroid hormone-related protein (PTH-rP) than MDA-231BR and MDA-231P in the absence or presence of transforming growth factor beta (TGF-beta). Furthermore, the anchorage-independent growth of MDA- 231BO in soft agar was not inhibited by TGF-beta, whereas TGF-beta profoundly inhibited the growth of MDA-231P and MDA-231BR. Insulin-like growth factor I (IGF-I) markedly promoted the anchorage-independent growth of MDA-231BO, whereas marginal or no stimulation was observed in MDA-231BR or MDA-231P, respectively. Our data suggest that these phenotypic changes allow breast cancer cells to promote osteoclastic bone resorption, survive, and proliferate in bone, which consequently leads to the establishment of bone metastases.

BRCA1 and prostate cancer

The breast cancer susceptibility gene BRCA1 on chromosome 17q21 encodes an 1863 amino acid protein that is important for normal embryonic development. Germline mutations of this gene are linked to a significantly increased lifetime risk for breast and/or ovarian cancer, and recent studies suggest that the same may be true for prostate cancer. Several activities that may contribute to the tumor suppressor function of BRCA1 have been identified via in vitro and experimental animal studies. These include (i) regulation of cell proliferation; (ii) participation in DNA repair/recombination processes related to the maintenance of genomic integrity; (iii) induction of apoptosis in damaged cells; and (iv) regulation of transcription. A second breast cancer susceptibility gene (BRCA2) operates in some of the same molecular pathways as BRCA1, and mutations of this gene predispose to breast and ovarian cancer and probably to other tumor types, including prostate cancer. Finally, recent studies from our laboratory suggest that BRCA1 modulates proliferation, chemosensitivity, repair of DNA strand breaks, apoptosis induction, and expression of certain key cellular regulatory proteins (including BRCA2 and p300) in human prostate cancer cells. These activities are consistent with a putative prostate tumor suppressor function of BRCA1.

Multifactor-dimensionality reduction reveals high-order interactions among estrogen-metabolism genes in sporadic breast cancer

One of the greatest challenges facing human geneticists is the identification and characterization of susceptibility genes for common complex multifactorial human diseases. This challenge is partly due to the limitations of parametric-statistical methods for detection of gene effects that are dependent solely or partially on interactions with other genes and with environmental exposures. We introduce multifactor-dimensionality reduction (MDR) as a method for reducing the dimensionality of multilocus information, to improve the identification of polymorphism combinations associated with disease risk. The MDR method is nonparametric (i.e., no hypothesis about the value of a statistical parameter is made), is model-free (i.e., it assumes no particular inheritance model), and is directly applicable to case-control and discordant-sib-pair studies. Using simulated case-control data, we demonstrate that MDR has reasonable power to identify interactions among two or more loci in relatively small samples. When it was applied to a sporadic breast cancer case-control data set, in the absence of any statistically significant independent main effects, MDR identified a statistically significant high-order interaction among four polymorphisms from three different estrogen-metabolism genes. To our knowledge, this is the first report of a four-locus interaction associated with a common complex multifactorial disease.

Breast cancer screening among American Samoan women

BACKGROUND

Little is known about breast cancer screening practices or predictors of age-specific screening for Samoan women.

METHODS

Through systematic, random sampling procedures, we identified and interviewed 720 adult (> or =30 years) Samoan women residing in American Samoa, Hawaii, and Los Angeles. Multivariate logistic regressions were performed to determine independent predictors for recent age-specific screening.

RESULTS

Only 55.6% of women (> or =30 years) had ever had a CBE and 32.9% of women (> or =40 years) had ever had a mammogram. Furthermore, only 24.4 and 22.4% of Samoan women (> or =40 years) residing in Hawaii and Los Angeles, respectively, had an age-specific mammogram within the prior year. Independent predictors of age-specific CBE screening included age, education, health insurance, ambulatory visit, and being a resident of Hawaii or Los Angeles; those for mammography included ambulatory visit and awareness of screening guidelines.

CONCLUSION

Population-based estimates of age-specific breast cancer screening among Samoan women are lower than the national objectives and those reported for other minorities. Targeted efforts that address doctor-patient communication on preventive behavior, improved access to health care services (especially in American Samoa), and focused educational awareness programs are needed to improve the dismal screening rates observed in this indigenous population.

Acceleration of mammary neoplasia in aromatase transgenic mice by 7,12-dimethylbenz[a]anthracene

Our studies using the aromatase transgenic mice model have shown that early exposure of mammary epithelium to in situ estrogen as a result of overexpression of aromatase predispose mammary tissue to preneoplastic changes. Here, we hypothesize that the preneoplastic changes induced by mammary estrogen in aromatase transgenic females may be susceptible to environmental carcinogens like 7,12-dimethylbenz[a]anthracene (DMBA), and may result in the acceleration and/or increase in the incidence of breast cancer. Results presented in this study show that tumors appeared in 25% of the mice that were treated with DMBA and all treated transgenic animals had microscopic evidence of neoplastic progression. Control non-transgenic females did not have significant changes even after treatment with DMBA. Consistent with increased neoplastic changes in DMBA-treated aromatase mice, we have seen an increase in the expression of genes involved in cell proliferation and cell cycle. We have also seen changes in the expression of oxidative stress markers and changes in estrogen-mediated growth factors. These studies indicate that more than one event is required for tumor formation, and that early estrogen exposure leading to preneoplastic changes in the mammary epithelial cells increases susceptibility to environmental carcinogens that may result in acceleration and/or an increase in the incidence of breast cancer.

Short-term tumor cell lines from breast cancer for use as autologous tumor cell vaccines in the treatment of breast cancer

OBJECTIVE

We tried to establish short-term cultures of autologous tumors from patients with breast carcinoma for potential use as active specific immunotherapy (i.e., autologous vaccine) after resection of primary breast cancer, and/or for the treatment of metastases.

METHODS

Between 10/90 and 12/99 the cell biology laboratory of the Hoag Cancer Center attempted to establish short-term tumor cell lines from 115 breast cancer specimens from 56 primary breast lesions, 17 axillary nodes, 14 other lymph node/soft tissue sites, 10 chest wall recurrences, and 6 thoracentesis of malignant pleural effusions. Success was defined by growth of 5 x 10(7) viable cells whose malignant nature and breast cancer origin was confirmed by histology of the submitted tissue, cell morphology and antigenic phenotyping. Variables associated with successful growth of short-term cell lines were examined.

RESULTS

Expansion to 5 x 10(7) cells was achieved for only 8/115 samples [7%] including two from chest wall recurrences, and one each from a supraclavicular node, an umbilical node, liver, omentum, and pleural fluid. Two of the successful cell lines were established from tissue that originally had been cryopreserved; the others were initiated from fresh tumor. The success rate was better from regional/distant metastases 7/55 (13%) compared to primary tumors 1/56 (1.8%) (p = 0.063). The success rate for tumors harvested at Hoag Hospital was 4/97 (4%) compared to 4/14 from (31%) distant sites, but all but one of the tumors from a distant geographic site was a metastatic lesion. Tumor cell lines were successfully established from metastatic lesions ranging in size from < 1.0 g to 19 g. Four patients were treated with their autologous vaccine in the setting of chemotherapy-refractory metastatic disease without any significant toxicity.

CONCLUSIONS

We were unable to establish short-term cell lines for most patients with primary or metastatic breast cancer using this methodology. However, two long-term cell lines have been established and characterized. Treatment with the autologous irradiated cell product was not associated with acute toxicity.

Persistent Genomic Instability in the YeastSaccharomyces cerevisiaeInduced by Ionizing Radiation and DNA-Damaging Agents

A "hypermutable" genome is a common characteristic of cancer cells, and it may contribute to the progressive accumulation of mutations required for the development of cancer. It has been reported that mammalian cells surviving exposure to gamma radiation display several highly persistent genomic instability phenotypes which may reflect a hypermutability similar to that seen in cancer. These phenotypes include an increased mutation frequency and a decreased plating efficiency, and they continue to be observed many generations after the radiation exposure. The underlying causes of this genomic instability have not been fully determined. We show here that exposure to gamma radiation and other DNA-damaging treatments induces a similar genomic instability in the yeast Saccharomyces cerevisiae. A dose-dependent increase in intrachromosomal recombination was observed in cultures derived from cells surviving gamma irradiation as many as 50 generations after the exposure. Increased forward mutation frequencies and low colony-forming efficiencies were also observed. Persistently elevated recombination frequencies in haploid cells were dominant after these cells were mated to nonirradiated partners, and the elevated recombination phenotype was also observed after treatment with the DNA-damaging agents ultraviolet light, hydrogen peroxide, and ethyl methanesulfonate. Radiation-induced genomic instability in yeast may represent a convenient model for the hypermutability observed in cancer cells.

Induction of anti-mammary cancer immunity by engaging the OX-40 receptor in vivo

The OX-40 receptor (OX-40R) is a member of the tumor necrosis factor receptor (TNF-R) superfamily that is expressed on activated CD4+ T cells. The OX-40R is a costimulatory molecule that induces CD4+ T cell activation when engaged by its ligand (OX-40 L; found on antigen presenting cells). In human and murine tumors, we have shown upregulation of the OX-40R on CD4+ T cells from tumor-infiltrating lymphocytes (TIL) and tumor-draining lymph node cells (TDLNC) but not on systemic CD4+ T cells, such as peripheral blood lymphocytes (PBL) or splenocytes. In order to examine potentially heightened anti-tumor immunity through enhanced costimulation when engaging OX-40R in vivo, we inoculated mice with a murine mammary cancer cell line (SM1) and then treated with a soluble form of the OX-40 L. Mice injected with a lethal inoculum of SM1 cells were given two intraperitoneal injections (days 3 and 7 post-inoculation) of 100 microg soluble OX-40 L. Seven of 28 treated mice survived the lethal tumor inoculum, as compared to one of 28 control mice, demonstrating a significant survival benefit with treatment (p = 0.0136, log rank analysis). Mice that did not develop tumor by day 90 were rechallenged; all remained tumor-free. Mice were also injected with a second mammary tumor line (4T1) and treated with OX-40L:Ig with similar therapeutic results. Activation of OX-40R+ CD4+ T cells during mammary cancer priming stimulated an antitumor immune response resulting in enhanced survival and protective anti-tumor immunity. These results should have practical applications for treatment modalities for patients with breast cancer.

Genetic susceptibility to breast cancer in French-Canadians: role of carcinogen-metabolizing enzymes and gene-environment interactions

Breast cancer is the most frequent malignancy among women. Since genetic factors such as BRCA1 and BRCA2 as well as reproductive history constitute only 30% of the cause, environmental exposure may play a significant role in the development of breast cancer. Likewise, the relevant enzymes involved in the biotransformation of xenobiotics (from tobacco smoke, diet or other environmental sources) might play a role in breast carcinogenesis. Since individuals with modified ability to metabolize these carcinogens could have a different risk for breast cancer, we investigated the role of cytochromes P-450 (CYP1A1, CYP2D6), glutathione-S-transferases (GSTM1, GSTT1, GSTP1) and N-acetyltransferases (NAT1, NAT2) gene variants in breast carcinogenesis. A case-control study was conducted on 149 women with breast carcinoma and 207 healthy controls, both of French-Canadian origin. The CYP1A1*4 allele was found to be a significant risk determinant of breast carcinoma (OR = 3.3, 95% CI 1.1-9.7), particularly among post-menopausal women (OR = 4.0, 95% CI 1.2-13.8). The frequency of NAT2 rapid acetylators was increased among smokers (OR = 2.6, 95% CI 0.8-8.2), while the NAT1*10 allele conferred a 4-fold increase in risk among women who consumed well-done meat (OR = 4.4, 95% CI 1.0-18.9). These data suggest that CYP1A1*4, NAT1 and NAT2 variants are involved in the susceptibility to breast carcinoma by modifying the impact of exogenous and/or endogenous exposures.

Screening for the major malignancies affecting women: current guidelines

Throughout their lifetimes, many women rely on the obstetrician-gynecologist to provide them with regular health care. Therefore the obstetrician-gynecologist should be able to provide comprehensive information regarding consensus screening recommendations for the major malignancies that occur in women. Additionally, a woman's health care provider should continually refine his or her cancer risk--assessment skills and should remain apprised of high-risk habits, family histories, and other cancer-predisposing factors that allow identification of those women in whom heightened surveillance or intervention may be appropriate. This article reviews the epidemiologic and risk factors associated with the major malignancies that affect women today and provides screening guidelines.

The privatization of risk

The privatization, or individualization, of risk factor knowledge has been largely responsible for a rising tide of criticism of epidemiology. The current debate seems polarized into 2 sides, those who support and those who attack "risk factor" epidemiology. This commentary aims to reinvigorate some of Geoffrey Rose's central arguments and show that this debate may miss a key point: a risk factor is a probabilistic concept that applies to an aggregate of individuals, not to a specific individual. Risk factor knowledge compels those in public health to seek actions that shift population distributions of these factors and, to do so, to understand their social, economic, and political determinants. The author links Rose's qualitative distinction between the causes of cases and the causes of incidence to an examination of the conceptual and quantitative limits of "individual risk" estimation. The attempt to predict individuals' futures on the basis of risk factor profile is especially prominent now with breast cancer. The author suggests reasons why a policy promoting private decision making about risk, while likely ineffective from a population standpoint, is viewed as the only feasible primary prevention option against this disease.

Endogenous estrogens as carcinogens through metabolic activation

A common thread linking the main risks for developing breast cancer in women is cumulative, excessive exposure to estrogen. The standard paradigm to account for this association focuses on increased cell proliferation caused by estrogen through estrogen receptor-mediated signal transduction accompanied by increased probability for mutation to occur during DNA synthesis. This chapter provides an overview of the mounting evidence, provided from cell culture and whole animal experimental studies, in support of a role for the oxidative metabolites of estrogen, in particular, the catechol estrogens, in the development of estrogen carcinogenesis. This provides a paradigm for how estrogens may contribute to the development of human breast cancer. The chapters that follow will fill in the details. Evidence shows that the catechols themselves are signaling molecules that work through the estrogen receptor. In addition, upon further oxidation, the catechols can give rise to reactive quinones capable of forming direct adducts with glutathione and purines in DNA and of redox cycling to generate reactive oxygen species that can cause oxidative damage. Estradiol and estrone, as well as their 4-hydroxy catechols, are carcinogenic in the Syrian golden hamster kidney, and ethinyl estradiol is a strong promoter of hepatocarcinogenesis in the rat. Increased oxidative DNA damage has been detected in target tissues after estrogen treatment in both animal model systems. Furthermore, several recent molecular epidemiologic studies have found that a polymorphism associated with a low-activity form of catechol-O-methyltransferase, an enzyme involved in the inactivation of catechol estrogens, is associated with an increased risk for developing breast cancer. The increased risk is observed in certain women, although the studies are not consistent on which subgroup of women (e.g., premenopausal or postmenopausal) is at increased risk, and one study detected no increased risk. Reasons for such discrepancies are discussed in light of factors, such as genetic polymorphisms and environmental/lifestyle susceptibility factors, which control the tissue-specific balance within cells among the estrogen metabolites. It is concluded that such factors will have to be identified through additional mechanistic studies and that, as they are identified, they can be incorporated into future molecular epidemiologic studies designed to determine their actual impact on cancer risk in human populations.

[Oral contraceptive and breast cancer: a case-control study]

OBJECTIVE

To investigate the association between breast cancer and the duration of use of oral contraceptives (OC), and age it started to be used in a population of Pelotas, Southern Brazil.

METHODS

There were identified 250 incident cases of breast cancer in patients aged 20 to 60 years from records of pathology laboratories and there were enrolled 1,020 controls drawn from hospital and neighbourhood population. For 90 cases identified in Pelotas, 270 hospital controls and 270 neighbourhood controls were selected, for another 78 cases in Pelotas, 234 controls were selected, and for 82 cases from other municipalities, 246 hospital controls were selected. Controls were matched by age. Adjusted analysis was performed using conditional logistic regression.

RESULTS

No association between oral contraceptive use and breast cancer was found (OR=1.1;CI95% 0.7 - 1.6 for hospital controls, and OR=0.9;CI95% 0.6 - 1.6 for neighbourhood controls) neither for different duration of use or starting age. To increase the test power, 250 cases and all 1020 controls were analyzed together, and an odds ratio of 1.6 (CI95% 1.0 - 2.4) was found for women older than 45 years of age who had been using oral contraceptives for five years or more.

CONCLUSIONS

No evidence was found of a general association between oral contraceptive use and breast cancer. When analyzing the whole date set, with all neighbourhood and hospital controls together, for women older than 45 years of age who had been using oral contraceptives for more than 5 years, it was found an increased risk almost statistically significant (p=0.05).

Effects of chemopreventive and antitelomerase agents on the spontaneous immortalization of breast epithelial cells

BACKGROUND

Activation of telomerase is an early event in the development of breast and other cancers that may lead to cell immortalization, a critical and rate-limiting step in cancer progression. Breast epithelial cells from women with Li-Fraumeni syndrome (LFS) immortalize spontaneously and reproducibly in culture. We, therefore, tested whether immortalization of these cells could be prevented by treating them with chemopreventive agents and by inhibiting telomerase activity.

METHODS

Noncancerous, preimmortal breast epithelial cells derived from a patient with LFS were treated for 3 months with nontoxic concentrations of the chemopreventive agents oltipraz, difluoromethylornithine, tamoxifen, and retinoic acid or with two different telomerase inhibitors. The frequency of spontaneous immortalization of LFS-derived cells was estimated by an approach based on fluctuation analyses. Statistical analyses were two-sided.

RESULTS

The frequency of spontaneous immortalization events of LFS-derived breast epithelial cells was reduced by long-term treatment with retinoic acid (P<0.001) or tamoxifen (P<0.05) compared with solvent-treated cells. The frequency of immortalization was also reduced by treating LFS-derived cells with an antitelomerase antisense oligonucleotide (P<0.001) or by inducing the cells to express a dominant negative mutant of telomerase (P<0.025) compared with cells treated with a control oligonucleotide or with empty vector, respectively.

CONCLUSIONS

Treatment of preimmortal LFS breast epithelial cells with chemopreventive and antitelomerase agents decreased the frequency of spontaneous immortalization in vitro. These studies validate the application of a new cell culture model system to screen the effects of novel chemopreventive agents by use of cell immortalization as an end point. The results also suggest that the telomerase ribonucleoprotein complex may be an important molecular target for breast cancer prevention.

Differences in genetic alterations between primary lobular and ductal breast cancers detected by comparative genomic hybridization

Infiltrating ductal (DC) and lobular carcinoma (LC) of the breast represent the most frequently observed varieties of invasive breast cancer, characterized by differences in their histological and clinical properties. Although comparative genomic hybridization (CGH) of invasive breast carcinomas has revealed a complex and consistent pattern of DNA copy number changes, the data with regard to type specific aberrations are limited. A comprehensive study was therefore performed on 19 LCs and 29 DCs to ascertain type-specific differences of unbalanced DNA copy number changes by CGH. Statistical analysis revealed significantly higher frequencies for underrepresentation of chromosomes 16q (p<0.01), 22 (p<0.05), and 17q (p<0.05), and a lower frequency for overrepresentation of chromosome 8q (p<0.01) in LC. Similar frequencies of non-random chromosomal changes in LC and DC were obtained for gain of 1q (74%/59%) and loss of 19p (53%/52%), parts of 1p (42%/41%) and 11q (21%/24%). Less frequently, gains mainly involving parts of chromosomes 20q, 20p, 3q, and 5p and partial losses of chromosomes 17p and 13 were observed in both groups of tumours. Minimal regions of overlapping amplifications were mapped to 17q23 exclusively in DC (17%) and 11q13-q14 in both DC and LC (21% and 11%, respectively). High occurrences of DNA copy number decreases were detected at the distal part of chromosomes 1p, 19 and 22, but further analysis is required to confirm these imbalances. It is suggested that the observed differences are involved in the development of type-specific properties of DC and LC.

Roles of Fas and Fas ligand during mammary gland remodeling

Mammary involution is associated with degeneration of the alveolar structure and programmed cell death of mammary epithelial cells. In this study, we evaluated the expression of Fas and Fas ligand (FasL) in the mammary gland tissue and their possible role in the induction of apoptosis of mammary cells. FasL-positive cells were observed in normal mammary epithelium from pregnant and lactating mice, but not in nonpregnant/virgin mouse mammary tissue. Fas expression was observed in epithelial and stromal cells in nonpregnant mice but was absent during pregnancy. At day 1 after weaning, high levels of both Fas and FasL proteins and caspase 3 were observed and coincided with the appearance of apoptotic cells in ducts and glands. During the same period, no apoptotic cells were found in the Fas-deficient (MRL/lpr) and FasL-deficient (C3H/gld) mice. Increase in Fas and FasL protein was demonstrated in human (MCF10A) and mouse (HC-11) mammary epithelial cells after incubation in hormone-deprived media, before apoptosis was detected. These results suggest that the Fas-FasL interaction plays an important role in the normal remodeling of mammary tissue. Furthermore, this autocrine induction of apoptosis may prevent accumulation of cells with mutations and subsequent neoplastic development. Failure of the Fas/FasL signal could contribute to tumor development.

Electric blanket use and breast cancer in the Nurses' Health Study

Electric and magnetic fields (EMFs) have been hypothesized to increase the risk of breast cancer, and electric blankets represent an important source of exposure to EMFs. The authors examined the relation between electric blanket use and invasive breast cancer in the Nurses' Health Study. On the biennial questionnaire in 1992, 87,497 women provided information on this exposure during three consecutive time periods. In a prospective analysis with 301,775 person-years of follow-up through 1996 (954 cases), the relative risk for any electric blanket use was not elevated (relative risk (RR) = 1.08, 95% confidence interval (CI): 0.95, 1.24) after controlling for breast cancer risk factors. There was a weak association between breast cancer and electric blanket use at least 16 years before diagnosis and long-term use in age-adjusted analyses but not in multivariate models. In a retrospective analysis of 1,318,683 person-years of follow-up (2,426 cases), the multivariate relative risk associated with use before disease follow-up began was null (RR = 1.05, 95% CI: 0.95, 1.16). Similar results were obtained in analyses stratified by menopause and restricted to estrogen receptor-positive breast cancers. While 95% confidence intervals for these estimates did not exclude small risks, overall, results did not support an association between breast cancer risk and exposure to EMFs from electric blankets.

Expression of Bcl-2 but not Bax or p53 correlates with in vitro resistance to a series of anticancer drugs in breast carcinoma

Programmed cell death is an important determinant of the response to chemotherapy. Among the factors controlling this process, a significant role is played by bcl-2, bax and p53. The in vitro chemosensitivity of the 177 breast carcinomas was assessed by the histoculture drug response assay (HDRA) using mitomycin C (MMC), 5-fluorouracil (5-Fu), adriamycin (ADM), cisplatin (CDDP), and cyclophosphamide (CPA). The susceptibility of Bcl-2-negative tumors to all the drugs killing was significantly higher than that of Bcl-2-positive tumors. No relationship between Bax or p53 immunoreactivity and sensitivity for any of anticancer drugs studied was demonstrated. Immunohistochemical results regarding Bcl-2 are promising in the evaluation of the sensitivity of cancer cells to a series of anticancer drugs and might be therapeutically useful as an indicator of response to adjuvant chemotherapy for breast cancer.

The value of early and double phase 99Tcm-sestamibi scintimammography in the diagnosis of breast cancer

The aim of this study was to assess the additional value of early and double phase scintimammography (SMM) with 99Tcm-sestamibi in the detection of breast cancer following initial evaluation by palpation and mammography. Altogether, 322 women with breast lesions evaluated prospectively by palpation, fine-needle aspiration and mammography were assigned a malignancy risk according to the results. Scintimammography was performed in all patients in the prone breast dependent position. Immediate and delayed views were obtained. Acquisition of immediate tracer uptake was termed 'early phase' SMM, whereas a combination of both immediate and delayed phase images was termed 'double phase' SMM. All patients underwent breast biopsy. Both early phase and double phase SMM detected eight of nine tumours in the low-risk group (88.8% sensitivity). In the uncertain cases (moderate-risk group), early phase SMM detected all malignant tumours, but double phase SMM missed one (92.3% sensitivity). In the high-risk group, early phase SMM missed two breast cancers (94.6% sensitivity) and double phase SMM missed four (89.2% sensitivity). Overall, early phase SMM had a sensitivity of 94.9% and a specificity of 80.2% in detecting breast cancer, whereas double phase SMM had a sensitivity of 89.8% and a specificity of 94.3%. Both methods had 100% sensitivity for tumours larger than 1 cm. In conclusion, SMM detected additional breast cancers following an initial evaluation by palpation, fine-needle aspiration and mammography. Our results suggest that double phase SMM is more specific than early phase SMM, although early phase SMM is more sensitive. Whether the interpretation of SMM results should rely on both early and delayed images, or early images alone, should be based on the relative risk of malignancy of the breast lesion as estimated by the initial evaluation.

Breast cancer in Mexican women: an epidemiological study with cervical cancer control

INTRODUCTION

In Mexico, breast cancer (BC) is one of the main causes of cancer deaths in women, with increasing incidence and mortality in recent years. Therefore, the aim of the study is identify possible risk factors related to BC.

METHODS

An epidemiological study of hospital cases of BC and controls with cervical uterine cancer (CUCA) was carried out at eight third level concentration hospitals in Mexico City. The total of 353 incident cases of BC and 630 controls with CUCA were identified among women younger than 75 years who had been residents of the metropolitan area of Mexico City for at least one year. Diagnosis was confirmed histologically in both groups. Variables were analyzed according to biological and statistical plausibility criteria. Univariate, bivariate and multivariate analyses were carried out. Cases and controls were stratified according to the menopausal hormonal status (pre and post menopause).

RESULTS

The factors associated with BC were: higher socioeconomic level (OR= 2.77; 95%CI = 1.77 - 4.35); early menarche (OR= 1.32; 95%CI= 0.88 - 2.00); old age at first pregnancy (>31 years: OR= 5.49; 95%CI= 2.16 - 13.98) and a family history of BC (OR= 4.76; 95% CI= 2.10 - 10.79). In contrast, an increase in the duration of the breastfeeding period was a protective factor (>25 months: OR= 0.38; 95%CI= 0.20 - 0.70).

CONCLUSIONS

This study contributes to the identification of risk factors for BC described in the international literature, in the population of Mexican women. Breastfeeding appears to play an important role in protecting women from BC. Because of changes in women's lifestyles, lactation is decreasing in Mexico, and young women tend not to breastfeed or to shorten the duration of lactation.

Rat strain-specific actions of 17beta-estradiol in the mammary gland: correlation between estrogen-induced lobuloalveolar hyperplasia and susceptibility to estrogen-induced mammary cancers

The genetically related ACI and Copenhagen (COP) rat strains display diametrically opposed susceptibilities to mammary cancer development when treated chronically with 17beta-estradiol (E2). Here, we compare the actions of E2 on cell proliferation and lobuloalveolar development in the mammary glands of female ACI and COP rats. After 12 wk of E2 treatment, the mammary glands of ACI rats exhibited a significantly greater proliferative response to E2, compared with COP rats, as evidenced by quantification of S phase fraction and development of lobuloalveolar hyperplasia. Focal regions of atypical epithelial hyperplasia were observed in ACI, but not COP, rats. These strain differences were not because of differences in circulating E2, progesterone or, prolactin. Two-thirds of the induced mammary cancers in ACI rats exhibited aneuploidy. The E2-induced mammary cancers regressed when hormone treatment was discontinued, indicating that they were estrogen-dependent. Progesterone receptor was expressed by the great majority of epithelial cells within the E2-induced atypical hyperplastic foci and the mammary carcinomas, suggesting a link between these lesions. These data demonstrate a correlation between E2 action in the induction of mammary cell proliferation and atypical epithelial hyperplasia and genetically conferred susceptibility to E2-induced mammary cancers.

Herceptin: increasing survival in metastatic breast cancer

Growth factors and their receptors play an important role in the pathogenesis of human cancer. The human epidermal growth factor receptor-2 (HER2) is overexpressed in approximately 30% of breast cancers and this is associated with poor clinical outcome. Overexpression of HER2 has been demonstrated to play a direct role in oncogenic transformation. Murine monoclonal antibodies (muMAbs) targeting the extracellular domain of the HER2 receptors suppress HER2-positive cancer cell growth, with muMAb 4D5 having particularly potent activity. A humanized form of muMAb 4D5 was generated by converting all but the antigen-binding region of muMAb 4D5 into human IgG consensus sequences. The humanized monoclonal antibody, Herceptin, preferentially targets HER2-overexpressing cells, produces responses in breast cancer patients and is well tolerated. In a pivotal phase III trial, Herceptin administered in combination with chemotherapy (anthracycline/cyclophosphamide or paclitaxel) was compared with chemotherapy alone. The combination was found to produce significant survival benefits in HER2-positive metastatic breast cancer patients. These results have led to the approval of Herceptin for clinical use in the USA and elsewhere.

The interferon-induced gene ISG12 is regulated by various cytokines as the gene 6-16 in human cell lines

The gene for ISG12 (originally designated p27) was isolated as an oestrogen-induced gene. The authors undertook a comprehensive study using quantitative RT-PCR, in which we delineate the regulation of ISG12 by seven different cytokines including interferons and poly(I). poly(C) in seven human cell lines of different origin. In all cell lines ISG12 is strongly induced by IFN-alpha and only slightly by IFNgamma. Poly(I).poly(C) induces ISG12 in a cell line-dependent manner, whereas none of the other cytokines tested elicited a response. Comparing the induction pattern of ISG12 to that of 6-16 a high degree of similarity was found. The induction levels varied, however, between cell lines.

Does antibacterial treatment for urinary tract infection contribute to the risk of breast cancer?

Low lignan status has been reported to be related to an elevated risk of breast cancer. Since lignan status is reduced by antibacterial medications, it is plausible to hypothesize that repeated use of antibiotics may also be a risk factor for breast cancer. History of treatment for urinary tract infection was studied for its prediction of breast cancer among 9,461 Finnish women 19-89 years of age and initially cancer-free. During a follow-up in 1973-1991, a total of 157 breast cancer cases were diagnosed. Women reporting previous or present medication for urinary tract infection at baseline showed an elevated breast cancer risk in comparison with other women. The age-adjusted relative risk was 1.34 (95% confidence interval (CI) = 0.98-1.83). The association was concentrated to women under 50 years of age. The relative risk for these women was 1.74 (95% CI 1.13-2.68), whereas it was 0.97 (95% CI 0.59-1.58) for older women. The relative risk in the younger age-group was 1.47 (95% CI 0.73-2.97) during the first 10 years of follow-up, and 1.93 (95% CI 1.11-3.37) for follow-up times longer than 10 years. These data suggest that premenopausal women using long-term medication for urinary tract infections show a possible elevated risk of future breast cancer. The results are, however, still inconclusive and the hypothesis needs to be tested by other studies.

Comparison of FDG-PET with MIBI-SPECT in the detection of breast cancer and axillary lymph node metastasis

PURPOSE

The purpose of this work was to compare [18F]2-deoxy-2-fluoro-D-glucose (FDG) PET and 99mTc-methoxyisobutylisonitrile (MIBI) SPECT in the detection of breast cancer and axillary lymph node metastasis in the same patients.

METHOD

FDG-PET and MIBI-SPECT were performed within 3 days for 40 women (age range 25-86 years old) with suspected breast cancer, in whom biopsies and/or mastectomies were performed. Both images were visually assessed, and the count ratio between tumor and normal tissue (T/N ratio) was calculated.

RESULTS

Thirty-eight patients had breast cancer, and the remaining two had benign breast lesions. The sensitivities of FDG-PET and MIBI-SPECT were 78.9 and 76.3% for breast cancer and 50.0 and 37.5% for axillary lymph node metastasis, respectively. The T/N ratio of breast cancer was significantly higher in FDG-PET (6.01 +/- 3.08 mean +/- SD) than that in MIBI-SPECT (3.48 +/- 1.21) (p = 0.01). Nonmalignant diffuse uptake of FDG in the breasts and the accumulation of MIBI in heart and liver occasionally obscured tumor uptake.

CONCLUSION

These results indicate that MIBI-SPECT is comparable with FDG-PET in detecting breast cancer. Neither FDG-PET nor MIBI-SPECT is sufficiently sensitive to rule out axillary lymph node metastasis.

Meta-analysis of studies on breast cancer risk and diet: the role of fruit and vegetable consumption and the intake of associated micronutrients

A meta-analysis was carried out, in order to summarise published data on the relationship between breast cancer, fruit and vegetable consumption and/or the intake of beta-carotene and vitamin C. Relative risks were extracted from 26 published studies from 1982 to 1997. Random and fixed effects models were used. Between studies, heterogeneity was found for vegetables, fruit, vitamin C but not for beta-carotene. Summary relative risk (RR) estimates based upon a random effects model, except for beta-carotene, for 'high consumption' compared with 'low consumption', derived from the studies satisfying the inclusion criteria were as follows: vegetable consumption: RR=0.75 (95% CI (confidence interval) 0.66-0.85) from 17 studies; fruit consumption: RR=0.94 (95% CI 0.79-1.11) from 12 studies; vitamin C: RR=0.80 (95% CI 0.68-0.95) from 9 studies; beta-carotene: RR=0.82 (95% CI 0.76-0.91) from 11 studies. This analysis confirms the association between intake of vegetables and, to a lesser extent, fruits and breast cancer risk from published sources. Increasing vegetable consumption might reduce the risk of breast cancer.

Economic evaluation of letrozole in the treatment of advanced breast cancer in postmenopausal women in Canada

OBJECTIVE

To determine the cost-effectiveness of initiation of second-line hormone therapy with letrozole in the treatment of advanced breast cancer in postmenopausal women in Canada, compared to megestrol acetate.

METHODS

A modified Markov model, incorporating seven health states, was designed to simulate the treatment of patients with advanced breast cancer from second-line hormone therapy to death. The model was constructed with data from a clinical trial, literature sources, and interviews with breast cancer treatment experts. Canadian experts provided information on resource utilization patterns and local costs were attached to these resources. The model was used to calculate mean survival time, time without progression, and total direct medical costs for patients initiating treatment with letrozole 2.5 mg or megestrol acetate 160 mg.

RESULTS

The mean survival time and time without progression for letrozole 2.5 mg patients were 28.3 months and 19.0 months, respectively, compared to 25.7 months and 16.5 months for megestrol acetate 160 mg patients. Total treatment costs for both groups were similar with the letrozole 2.5 mg group costing dollar 20,068 per patient, dollar 1061 more than the megestrol acetate 160 mg group (dollar CAN, 1996). The cost-effectiveness ratio for letrozole 2.5 mg with respect to megestrol was dollar 5051 per year of life gained. Sensitivity analysis showed that this ratio was sensitive to variations in the probabilities governing disease progression.

CONCLUSIONS

Advanced breast cancer patients initiating second-line hormone therapy with letrozole 2.5 mg have better clinical outcomes than patients receiving megestrol acetate 160 mg. Furthermore, this benefit comes at an acceptable cost to the Canadian health care system.