Overexpression of BLM promotes DNA damage and increased sensitivity to platinum salts in triple-negative breast and serous ovarian cancers.

Background: Platinum-based therapy is an effective treatment for a subset of triple-negative breast cancer and ovarian cancer patients. In order to increase response rate and decrease unnecessary use, robust biomarkers that predict response to therapy are needed. Patients and methods: We performed an integrated genomic approach combining differential analysis of gene expression and DNA copy number in sensitive compared with resistant triple-negative breast cancers in two independent neoadjuvant cisplatin-treated cohorts. Functional relevance of significant hits was investigated in vitro by overexpression, knockdown and targeted inhibitor treatment. Results: We identified two genes, the Bloom helicase (BLM) and Fanconi anemia complementation group I (FANCI), that have both increased DNA copy number and gene expression in the platinum-sensitive cases. Increased level of expression of these two genes was also associated with platinum but not with taxane response in ovarian cancer. As a functional validation, we found that overexpression of BLM promotes DNA damage and induces sensitivity to cisplatin but has no effect on paclitaxel sensitivity. Conclusions: A biomarker based on the expression levels of the BLM and FANCI genes is a potential predictor of platinum sensitivity in triple-negative breast cancer and ovarian cancer.

Abnormalities of the inactive X chromosome are a common feature of BRCA1 mutant and sporadic basal-like breast cancer.

As a clinical entity, breast cancer appears to be a series of subforms, each with a relatively specific molecular phenotype. Among the characteristics that differentiate these subforms are sex hormone receptor expression, HER2 expression, p53 mutation, high-grade histopathology, and particular gene expression array patterns. Sporadic basal-like breast cancer is one such form. It is a relatively common, high-grade, hormone receptor and HER2-expression-negative, p53 mutation-bearing tumor and is particularly lethal. Although wild type for BRCA1, it is a sporadic phenocopy of most cases of BRCA1(/) breast cancer. Not only do the cells of the two tumors resemble one another with respect to the above-noted characteristics, they also share a defect in the maintenance of an intact, inactive X chromosome (Xi). Other high-grade and most low-grade tumors are rarely defective at Xi. This evidence suggests that an Xi defect contributes to the evolution of both sporadic and BRCA1(/) basal-like breast tumors.

Knowledge, satisfaction, and perceived cancer risk among women diagnosed with ductal carcinoma in situ.

The prevalence of ductal carcinoma in situ (DCIS) has increased through more widespread use of screening mammography. Little is known about what women with DCIS understand about their disease and future health. Although there is a wealth of information about the psychological characteristics of women with invasive breast cancer, there is virtually no information about women who have received treatment for DCIS. Seventy-six women diagnosed with DCIS who were identified through the Duke University Tumor Registry completed a mailed self-administered questionnaire including a broad range of items to measure knowledge, satisfaction with care, risk perceptions, and psychological distress. Women with DCIS have knowledge deficits about DCIS and breast cancer, as well as concerns about recurrence and misperceptions about the likelihood for DCIS metastasis. Women were generally satisfied with their care. They were less satisfied with information related to prognosis and with perceived support from their doctors. The results of this study suggest several areas of concern for women diagnosed with DCIS. Data about risk perceptions, knowledge, and attitudes in women diagnosed with DCIS provide important preliminary ideas for future studies. In view of the frequency of the DCIS diagnosis, future investigation should be conducted to build on these findings.

Induction of topoisomerase II activity after ErbB2 activation is associated with a differential response to breast cancer chemotherapy.

ErbB2 (HER-2) gene amplification and overexpression have been shown to predict a better outcome with doxorubicin-based chemotherapy as opposed to alkylator-based chemotherapy in early stage breast cancer. To understand the mechanism of differential response to these two regimens, we have evaluated the effect of signaling through the ErbB2 receptor on downstream enzymes that may affect drug response, using two different models. The first system employs breast cancer cells that have high levels of endogenous ErbB2 by gene amplification (BT-474 and SKBR3 cells). The second system allows us to isolate the effect of ErbB2 receptor-mediated intracellular signaling using an epidermal growth factor receptor-ErbB2 chimeric receptor activated by epidermal growth factor. Our experiments show that the cytotoxicity of doxorubicin is inhibited in ErbB2+ breast cancer cells by the anti-ErbB2 antibody, Herceptin. This is accompanied by a decrease in topoisomerase (topo) IIalpha protein and activity, suggesting that this is the mechanism of change in doxorubicin response. In addition, a 10-100-fold (1-2 log) decrease in the LD(50) of doxorubicin is seen after ErbB2 activation using the chimeric receptor model. Furthermore, we see a 100-fold decrease in the LD(50) of etoposide, another topo II inhibitor. This increase in doxorubicin sensitivity is associated with a 4.5-fold increase in the amount of topo IIalpha protein and an increase in topo II activity as measured by DNA decatenating and unknotting activities, as well as cleavable complex formation. In contradistinction to doxorubicin, we have observed an increased resistance to cyclophosphamide chemotherapy after chimeric receptor activation. We propose that the differential benefit seen with doxorubicin- versus alkylator-based chemotherapy in ErbB2+ breast cancer is due, in some cases, to ErbB2-mediated topo IIalpha activation. These data also suggest hypotheses for the optimal sequencing of Herceptin and chemotherapy agents in ErbB2+ breast cancer.

Surgical management of high-risk patients.

Within the past decade, scientists have reported the discovery of potent genes that predispose to major cancers, including breast, ovarian, and colorectal cancer. The discovery of human cancer susceptibility genes is important for fundamental research into the cause of cancer. In addition, these discoveries will certainly have profound implications for the prevention and diagnosis of breast cancer. However, it is not yet clear whether and to what extent cancer susceptibility genes will alter the treatment of cancer. While breast cancer is an important malignant disease in women, it is hoped that knowledge gained from the management of this common disease will provide a template for the approach to other malignancies, caused by hereditary factors. In this paper, we will review the state of knowledge about genes that predispose to breast cancer. Our focus will be to summarize the available information, addressing how genetic factors may alter the initial approach to cancer in the breast. We will concentrate on the surgical management of early breast cancer. Issues include the use of limited surgery with radiation (breast conservation), the approach to the opposite breast, and prophylactic mastectomy in patients at high risk.

Testing for hereditary breast and ovarian cancer in the southeastern United States.

OBJECTIVES: To detail characterization of mutations and uncharacterized variants in the breast cancer susceptibility genes BRCA1 and BRCA2, as observed in a population of breast cancer patients from the southeastern United States, and to examine baseline characteristics of women referred for counseling and testing and provide a preliminary look at how counseling and testing affected intentions toward prophylactic surgery. BACKGROUND: Mutations in the BRCA1 and BRCA2 genes give rise to a dramatically increased risk of developing breast or ovarian cancer or both. There are many reports about special populations in which deleterious mutations are present at a high frequency. It is useful to study these genes in more heterogeneous populations, reflecting different geographic regions. Interest in preventive surgery for gene carriers is high in women and their surgeons. METHODS: Women were recruited through a prospective clinical trial of counseling and free genetic testing. BRCA1 and BRCA2 were screened for mutations using standard techniques, and results were given to participants. Baseline questionnaires determined interest in preventive surgery at the beginning of the study. Follow-up questionnaires for those who completed testing surveyed interest in prophylactic surgery after counseling and receiving test results. RESULTS: Of 213 women who completed counseling and testing, 44 (20.6%) had 29 separate mutations; there were 11 Jewish women carrying three founder mutations. Twenty-eight women (13.1%) had uncharacterized variants in BRCA1 or BRCA2; nine were not previously reported. Women overestimated their chances of possessing a deleterious gene mutation compared to a statistical estimate of carrier risk. A number of women changed their intentions toward preventive surgery after genetic counseling and testing. CONCLUSIONS: Hereditary breast cancer due to mutations in BRCA1 and BRCA2 was a heterogeneous syndrome in the southeastern United States. Most mutations were seen just once, and uncharacterized variants were common and of uncertain clinical significance. In general, positive test results tended to reinforce intentions toward prophylactic surgery. In contrast, women not interested in surgery at the time of entry tended to remain reluctant after testing and counseling.

Inhibition of mitogen-activated protein kinase and phosphatidylinositol 3-kinase activity in MCF-7 cells prevents estrogen-induced mitogenesis.

Estrogen acts to promote DNA synthesis in the MCF-7 human breast cancer cell line via its interaction with high levels of estrogen receptor. The primary mode of estrogen action has been considered to be through transcriptional activation of genes containing estrogen response elements, including the immediate early genes c-myc and fos. Recent reports have indicated that estrogen, acting through the estrogen receptor, is capable of inducing the mitogen-activated protein kinase (MAPK) cytoplasmic signaling cascade. In this study, specific small molecule inhibitors of MAPK and phosphatidylinositol 3-kinase activity were used to determine the influence of these cascades on estrogen-mediated mitogenesis. Phosphatidylinositol 3-kinase inhibitors, LY294002 and wortmannin, as well as inhibitors of MAPK kinase-1, PD098059 and U0126, decreased the fraction of cells entering DNA synthesis after treatment with 17beta-estradiol. These compounds did not inhibit expression of myc or fos. However, the drugs did prevent the accumulation of cyclin D1 and hyperphosphorylated retinoblastoma protein, indicating that the block occurred at, or prior to, this point in the cell cycle. Although these compounds were effective in preventing estrogen-mediated mitogenesis, the downstream kinases extracellular signal-regulated kinase 1, extracellular signal-regulated kinase 2, and protein kinase B were not activated over basal levels by estrogen treatment. These studies suggest that estrogen initiates mitogenesis by inducing the transcription of immediate early genes, but cytoplasmic signaling pathways play an important role in the control of subsequent events in the cell cycle.

Plasma D-dimer levels in operable breast cancer patients correlate with clinical stage and axillary lymph node status.

PURPOSE: To investigate the relationship between preoperative plasma D-dimer levels and extent of tumor involvement in operable breast cancer patients. PATIENTS AND METHODS: A total of 140 preoperative plasma specimens were obtained from women scheduled to undergo diagnostic breast biopsies. Ninety-five patients in the initial group went on to undergo axillary lymph node dissection. Of the 140 patients from whom plasma samples were obtained, 102 were subsequently diagnosed with invasive breast carcinoma, nine were subsequently diagnosed with ductal carcinoma-in-situ, and 20 were subsequently diagnosed with benign breast disease. Plasma D-dimer levels were quantitated using a commercially available immunoassay kit (DIMERTEST; American Diagnostica, Greenwich, CT). The relationships between plasma D-dimer and other prognostic variables (tumor size, estrogen receptor, progesterone receptor, nuclear grade, histologic grade, lymphovascular invasion, and clinical stage grouping) were then examined using univariate and multivariate linear and logistic regression analyses. RESULTS: Median plasma D-dimer levels were significantly higher in patients with invasive carcinoma than those patients with either benign breast disease or carcinoma-in-situ (P =.0001). A significant relationship existed between the presence of elevated D-dimer (> 100 ng/mL) and involved axillary lymph nodes (chi(2) test; P =.001). Elevated D-dimer levels predicted positive lymph node involvement in both univariate regression (P =.0035) and multivariate linear regression (P =.012) models. In addition, elevated D-dimer levels predicted the presence of lymphovascular invasion in univariate logistic regression (P =. 0025) and multivariate logistic regression analysis (P =.0053). Quantitative D-dimer levels were highly correlated with clinical stage grouping (analysis of variance test; P =.002). CONCLUSION: Plasma D-dimer levels were markers of lymphovascular invasion, clinical stage, and lymph node involvement in operable breast cancer. This correlation suggests that detectable fibrin degradation, as measured by plasma D-dimer, is a clinically important marker for lymphovascular invasion and early tumor metastasis in operable breast cancer.

Isolation and initial characterization of the BRCA2 promoter.

The hereditary breast cancer susceptibility gene, BRCA2, is considered to be a tumor suppressor gene that may be involved in the cellular response to DNA damage. The transcript for this gene is cell cycle regulated with mRNA levels reaching a peak just before the onset of DNA synthesis. In order to define the mechanisms by which BRCA2 is transcriptionally regulated, we have begun to study upstream regulatory sequences. In this report, we define a minimal promoter region that has strong activity in human breast epithelial cells. Deletions of this sequence narrowed the strong basal activity to a region extending from -66 to +129 with respect to the BRCA2 transcriptional start site. This sequence demonstrated cell cycle regulated activity with kinetics similar to the endogenous transcript. Examination of the sequence revealed several consensus binding sites for transcription factors including an E-box, E2F and Ets recognition motifs. Electrohoretic mobility shift assays revealed specific protein binding to two sequences upstream of the start site; the palindromic E-box and an Ets/E2F site. Site-directed mutagenesis of either of these sites reduced both the basal activity in log phase cells and the cell cycle regulated activity of the promoter. Mutational inactivation of both sites within the same construct effectively eliminated promoter activity. Antibodies to candidate transcription factors used in super shift experiments revealed specific interactions between the BRCA2 promoter and the basic region/helix - loop - helix containing USF-1 and 2 proteins and Elf-1, an Ets domain protein. Binding of these factors depended upon the presence of intact recognition sequences. The USF factors were shown to bind predominantly as a heterodimeric complex of USF-1 and 2 while Elf-1 bound the promoter when it was not occupied by USF. Co-transfection studies with USF proteins and the varicella zoster IE62 protein provide evidence for the involvement of endogenous and exogenous USF in the activation of the BRCA2 promoter. We propose that interactions between USF-1, USF-2 and Elf-1 play an important role in the transcriptional regulation of the BRCA2 gene.

Bcl10 is not a target for frequent mutation in human carcinomas.

The recently described Bcl10 gene has been suggested to be a major target gene for inactivation in a variety of human cancers. In order to further evaluate the role of this gene in human adult malignancies, we have analysed a series of carcinomas for mutations in the Bcl10 gene. We have screened a panel of 174 carcinoma samples in total, comprised of 47 breast, 36 epithelial ovarian, 36 endometrial, 12 cervical, 23 colorectal and 20 head/neck carcinomas, all unselected for grade or stage. This panel reflects, in part, tumours reported to have involvement of the 1p22 region of chromosome 1, the region harbouring the Bcl10 gene. No deleterious mutations were detected in any of the samples analysed, strongly suggesting that Bcl10 is not a common target for inactivation in adult malignancies and that BCL10 is not the gene targeted for frequent inactivation at 1p22.

Is axillary lymph node dissection indicated for early-stage breast cancer? A decision analysis.

PURPOSE: Axillary lymph node dissection (ALND) has been a standard procedure in the management of breast cancer. In a patient with a clinically negative axilla, ALND is performed primarily for staging purposes, to guide adjuvant treatment. Recently, the routine use of ALND has been questioned because the results of the procedure may not change the choice of adjuvant systemic therapy and/or the survival benefit of a change in adjuvant therapy would be small. We constructed a decision model to quantify the benefits of ALND for patients eligible for breast-conserving therapy. METHODS: Patients were grouped by age, tumor size, and estrogen receptor (ER) status. The model uses the Oxford overviews and three combined Cancer and Leukemia Group B studies. We assumed that patients who did not undergo ALND received axillary radiation therapy and that the two procedures are equally effective. All chemotherapy combinations were assumed to be equally efficacious. RESULTS: The largest benefits from ALND are seen in ER-positive women with small primary tumors who might not be candidates for adjuvant chemotherapy if their lymph nodes test negative. Virtually no benefit results in ER-negative women, almost all of whom would receive adjuvant chemotherapy. When adjusted for quality of life (QOL), ALND may have an overall negative impact. In general, the benefits of ALND increase with the expected severity of adjuvant therapy on QOL CONCLUSION: Our model quantifies the benefits of ALND and assists decision making by patients and physicians. The results suggest that the routine use of ALND in breast cancer patients should be reassessed and may not be necessary in many patients.

Attitudes, knowledge, and risk perceptions of women with breast and/or ovarian cancer considering testing for BRCA1 and BRCA2.

PURPOSE: This study examined baseline knowledge, beliefs, and risk perceptions among a group of 200 women with breast and/or ovarian cancer who participated in a trial designed to improve decision making about genetic testing for BRCA1 and BRCA2. PATIENTS AND METHODS: Women were identified by self-referral, physician referral, and tumor registry extraction and invited to participate in a randomized trial in which testing for BRCA1 and BRCA2 was offered free of charge. Subjects completed baseline questionnaires and interviews that assessed knowledge, attitudes, and perceptions of risk of having an alteration in BRCA1 or BRCA2. RESULTS: Sixty percent of women overestimated their chances of having a BRCA1 or BRCA2 mutation compared with estimates from a BRCA1/BRCA2 risk model. Women who have at least three relatives with breast or ovarian cancer were one third (95% confidence interval, 0.2 to 0.6) as likely to overestimate their risk of having a BRCA1 or BRCA2 mutation compared with women who have two or fewer affected relatives. Knowledge was limited about BRCA1 and BRCA2 mutations and cancer risk associated with gene mutations. Eighty-four percent of the women indicated a probable or definite interest in testing. CONCLUSION: A high proportion of the high-risk women in this study had knowledge deficits about BRCA1 and BRCA2 and overestimated their risk of having a mutation. Although some degree of caution should be used in generalizing the results of this study to practice settings, the data provide insight into the challenges clinicians will face in communicating with patients about cancer genetics.

Overestimation of hereditary breast cancer risk.

OBJECTIVE: To find out how women with breast or ovarian cancer rate their chances of carrying hereditary factors for these cancers and to determine the extent to which they overestimate their risk. SUMMARY BACKGROUND DATA: BRCA1 and BRCA2 are genes that cause breast and ovarian cancer when they are inherited in families. Testing for disease-associated mutations in these genes is now available commercially. Previous studies have shown that women overestimate their chances of carrying mutations. However, women's perceptions of risk have not been compared to objective estimates or to actual BRCA1 and BRCA2 testing results. METHODS: This study examines estimates of carrying BRCA1 and BRCA2 mutations among women participating in a randomized trial comparing alternative precounseling educational materials. Estimates were provided by participants in a baseline mailed survey. Estimates given by participants were compared to those given by an expert panel and by a statistical model. Testing was offered free of charge and was done in an academic laboratory using standard techniques. Baseline estimates of participating women were compared to the estimates of the expert panel, to the carrier probability provided by the statistical model, and to actual testing results. RESULTS: Women who have a personal history of breast or ovarian cancer significantly overestimate their risk of carrying hereditary factors for breast and ovarian cancer. Self-estimates exceeded the estimates of experts and a statistical model. One hundred women completed testing, and 21 mutations in BRCA1 or BRCA2 were found. Many test-negative women also overestimated their hereditary risk. Some women with a high carrier probability were negative for BRCA1 and BRCA2 mutations. CONCLUSIONS: Overestimation of hereditary factors is common among affected women with a family history of cancer. Pretest education and counseling should reduce these high-risk perceptions. Better estimates of carrier probability will direct more intensive clinical services and research.

Complex response of breast epithelial cell lines to topoisomerase inhibitors.

The topoisomerase inhibitors, camptothecin and etoposide target the activity of topoisomerase I and II respectively. These agents, or their analogues, are undergoing clinical trials for the treatment of metastatic breast cancer. In this study, we examined the response of eight breast epithelial cell lines, including six lines derived from breast cancers and two immortalized normal epithelial lines to camptothecin and etoposide. The lines varied by 700 fold in their sensitivity to the growth inhibiting effects of camptothecin and 30 fold in their response to etoposide. The BT474 line was the most resistant to both agents. The other cell lines did not have uniform sensitivity to both drugs, i.e., some lines were sensitive to one drug but relatively resistant to the other. A variety of parameters in these lines were analyzed to elucidate mechanisms of resistance including S phase, doubling time, expression and activity of topoisomerase I and II, expression of mdr-1, p53 status, cell cycle arrest, level of apoptosis, and expression of the apoptotic proteins Bcl-2 and Bax. We found that low levels of the topo I protein and its enzymatic activity were associated with increased resistance to camptothecin. This was not true for topo II activity and etoposide. Increased apoptotic responses were generally observed in cell lines that were sensitive to etoposide and this correlated with low ratios of Bcl-2/Bax protein. No single parameter was entirely predictive of response. However, the BT474 line displayed a series of characteristics including slow growth, the presence of mutant p53, low topo I activity, and a high Bcl-2/Bax ratio which together likely contributed to the resistance of this line to both etoposide and camptothecin.

Use of paravertebral block anesthesia in the surgical management of breast cancer: experience in 156 cases.

OBJECTIVE: To assess safety and efficacy of the regional anesthetic technique paravertebral block for operative treatment of breast cancer, and to compare postoperative pain, nausea, vomiting, and length of hospital stay in patients undergoing breast surgery using paravertebral block and general anesthesia. BACKGROUND: General anesthesia is currently the standard technique used for surgical treatment of breast cancer. Increasing hospital costs have focused attention on reducing the length of hospital stay for these patients. However, the side effects and complications of general anesthesia preclude ambulatory surgery for most patients undergoing breast surgery. In April 1994, the authors initiated the use of paravertebral block anesthesia for patients undergoing primary breast cancer surgery. A review of our early experience revealed that this regional anesthetic technique enables effective anesthesia for operative procedures of the breast and axilla, reduces postoperative nausea and vomiting, and provides prolonged postoperative sensory block that minimizes narcotic requirements. METHODS: A retrospective analysis of 145 consecutive patients undergoing 156 breast cancer operations using paravertebral block and 100 patients undergoing general anesthesia during a 2-year period was performed. Anesthetic effectiveness and complications, inpatient experience with postoperative pain, nausea, vomiting, and length of stay were measured. RESULTS: Surgery was successfully completed in 85% of the cases attempted by using paravertebral block alone, and in 91% of the cases, surgery was completed by using paravertebral block supplemented with local anesthetic. There was a 2.6% incidence of complications associated with block placement. Twenty percent of patients in the paravertebral group required medication for nausea and vomiting during their hospital stay compared with 39% in the general anesthesia group. Narcotic analgesia was required in 98% of general anesthesia patients, as opposed to 25% of patients undergoing paravertebral block. Ninety-six percent of patients having paravertebral block anesthesia were discharged within the day of surgery, compared with 76% of patients who had a general anesthetic. CONCLUSIONS: Paravertebral block can be used to perform major operations for breast cancer with minimal complications and a low rate of conversion to general anesthesia. Paravertebral block markedly improves the quality of recovery after breast cancer surgery and provides the patient with the option of ambulatory discharge.

Predicting response to adjuvant and radiation therapy in patients with early stage breast carcinoma.

BACKGROUND: Screening and surveillance is increasing the detection of early stage breast carcinoma. The ability to predict accurately the response to adjuvant therapy (chemotherapy or tamoxifen therapy) or postlumpectomy radiation therapy in these patients can be vital to their survival, because this prediction determines the best postsurgical therapy for each patient. METHODS: This study evaluated data from 226 patients with TNM Stage I and early Stage II breast carcinoma and included the variables p53 and c-erbB-2 (HER-2/neu). The area under the receiver operating characteristic curve (Az) was the measure of predictive accuracy. The prediction endpoints were 5- and 10-year overall survival. RESULTS: For Stage I and early Stage II patients, the 5- and 10-year predictive accuracy of the TNM staging system were at chance level, i.e., no better than flipping a coin. Both the 5- and 10-year artificial neural networks (ANNs) were very accurate--significantly more so than the TNM staging system (Az 5-year survival, TNM = 0.567, ANN = 0.758; P < 0.001; Az 10-year survival, TNM = 0.508, ANN = 0.894; P < 0.0001). For patients not receiving postsurgical therapy and for either chemotherapy or tamoxifen therapy, the ANNs containing p53 and c-erbB-2 and the number of positive lymph nodes were accurate predictors of survival (Az 5-year survival, 0.781, 0.789, and 0.720, respectively). CONCLUSIONS: The molecular genetic variables p53 and c-erbB-2 and the number of positive lymph nodes are powerful predictors of survival, and using ANN statistical models is a powerful method for predicting responses to adjuvant therapy or radiation therapy in patients with breast carcinoma. ANNs with molecular genetic prognostic factors may improve therapy selection for women with early stage breast carcinoma.

Expression of Tie2/Tek in breast tumour vasculature provides a new marker for evaluation of tumour angiogenesis.

Endothelial receptor tyrosine kinases may play important roles in pathological vascular growth, particularly in tumours. In this study, immunohistochemistry was used to evaluate the expression of a novel endothelial receptor tyrosine kinase, Tie2/Tek, in the endothelium of vascular 'hotspots' in normal breast tissue (n = 10), benign breast lesions (n = 10) and in breast tumours (n = 123). Tie2 expression was detected in the endothelium of all breast tissues examined. However, the strongest expression of Tie-2 was seen in vascular 'hot spots' within the inflammatory infiltrate at the periphery of invasive tumours. Moreover, the proportion of Tie2-positive vessels (Tie2 counts/CD31 counts) was significantly higher in breast tumours than the proportion of Tie2-positive vessels in either normal breast tissue or benign breast lesions (P = 0.004 and 0.0001 respectively). These data are consistent with a role for Tie2 in tumour angiogenesis and demonstrate the potential use of Tie2 expression as a novel marker of the tumour vasculature.

Predicting breast cancer invasion with artificial neural networks on the basis of mammographic features.

PURPOSE: To evaluate whether an artificial neural network (ANN) can predict breast cancer invasion on the basis of readily available medical findings (ie, mammographic findings classified according to the American College of Radiology Breast Imaging Reporting and Data System and patient age). MATERIALS AND METHODS: In 254 adult patients, 266 lesions that had been sampled at biopsy were randomly selected for the study. There were 96 malignant and 170 benign lesions. On the basis of nine mammographic findings and patient age, a three-layer backpropagation network was developed to predict whether the malignant lesions were in situ or invasive. RESULTS: The ANN predicted invasion among malignant lesions with an area under the receiver operating characteristic curve (Az) of .91 +/- .03. It correctly identified all 28 in situ cancers (specificity, 100%) and 48 of 68 invasive cancers (sensitivity, 71%). CONCLUSION: The ANN used mammographic features and patient age to accurately classify invasion among breast cancers, information that was previously available only by means of biopsy. This knowledge may assist in surgical planning and may help reduce the cost and morbidity of unnecessary biopsy.

BRCA1 expression is not directly responsive to estrogen.

Expression of the breast cancer susceptibility gene, BRCA1, is induced by 17-beta estradiol (E2) in estrogen receptor containing breast cancer cell lines. Our previous studies have shown that BRCA1 transcription is also regulated with the cell cycle, reaching maximal levels just before the onset of DNA synthesis. In this study, we have examined whether the estrogen induction of BRCA1 is direct or is a result of the mitogenic activity of the hormone. Four lines of evidence lead us to conclude that E2 induces BRCA1 primarily through an increase in DNA synthesis: (1) The kinetics and magnitude of induction are different from the directly E2 inducible gene, pS2; (2) Induction of BRCA1, but not pS2, is blocked by cycloheximide indicating that de novo protein synthesis is required; (3) Other hormonal and growth factor treatments that induce DNA synthesis have a similar effect, including IGF-1, EGF and DNA synthetic flares induced by tamoxifen and retinoic acid; (4) BRCA1 genomic fragments near the 5' end of the gene containing putative estrogen response elements fail to respond to E2 when transfected into breast cancer cell lines. The most consistent explanation for these findings and other published studies is that BRCA1 transcription is induced as a result of the mitogenic activity of E2 in estrogen receptor positive cells.