Neuroblastoma and parental occupation

Objectives: We evaluated parental occupation and the risk of neuroblastoma using data from a large case–control study conducted by the Children's Cancer Group and the Pediatric Oncology Group.Methods: We compared the distribution of 73 paternal and 57 maternal occupational groups among 504 newly diagnosed cases of neuroblastoma and individually matched controls obtained by telephone random digit dialing in the United States and Canada.Results: An increased risk of neuroblastoma was found for fathers employed as broadcast, telephone and dispatch operators (odds ratio [OR]=6.1; 95% confidence interval [CI]=0.7–50.9), electrical power installers and power plant operators (OR=2.7; CI=0.9–8.1), landscapers and groundskeepers (OR=2.3; CI=1.0–5.2), and painters (OR=2.1; CI=0.9–4.8). Elevated odds ratios were found for mothers employed as farmers and farm workers (OR=2.2; CI=0.6–8.8), florists and garden store workers (OR=2.4; CI=0.6–9.9), hairdressers and barbers (OR=2.8; CI=1.2–6.3), electric power installers and power plant operators, and sailors, fishers, and railroad workers. No increase in risk was found for other paternal occupations previously associated, including electricians, electrical equipment assemblers and repairers (OR=1.1; CI=0.6–2.0), or welders (OR=0.5; CI=0.1–1.6).Conclusion: The study reinforced some prior evidence of increased risks in electrical, farming and gardening, and painting occupations, but failed to confirm other previously reported associations. Further analyses of exposure to electromagnetic fields, metals, solvents, and pesticides are currently under way.     

Repetitive 5-aminolevulinic acid-mediated photodynamic therapy on human glioma spheroids

The response of human glioma spheroids to repetitive 5-aminolevulinic acid-mediated photodynamic therapy (PDT) was investigated. In all cases, light fluences were kept below toxic thresholds to simulate conditions typically found at 1–2cm depths in brain adjacent to tumor. Significant inhibition of spheroid growth was observed following multiple PDT treatments at sub-threshold light fluences. The effect appears to be insensitive to the treatment intervals investigated (weekly or bi-monthly). In all cases, suppression of growth was observed for the duration of treatment. Low fluence rates (5mWcm^–2) appear to be more effective than high fluence rates (25mWcm^–2). No evidence of PDT resistance was found in this investigation.     

Role of Ceramide During Cisplatin-induced Apoptosis in C6 Glioma Cells

Cisplatin is commonly used for the treatment of malignant brain tumors. However, the mechanisms of cell death by cisplatin are not fully understood. Therefore, the present study was designed to elucidate the apoptotic signaling pathway(s) activated by cisplatin in a C6 rat glioma cell line. C6 cells were treated with various concentrations of cisplatin (0.2–10g/ml) for 24–72h. At 10g/ml cisplatin, over 90% of the cells became dead at 72h. Apoptotic death was confirmed by condensation and fragmentation of nuclei, and DNA laddering. Even in cells treated with 1.5g/ml cisplatin, typical apoptotic cells were observed at 72h. The intracellular level of ceramide, measured Escherichia coli diacylglycerol kinase markedly increased during 24–72h after the addition of 10g/ml cisplatin. The activity of caspase-3(-like) proteases increased and reached a peak at 48h. Inhibitors of caspases reduced the number of apoptotic cells. Pretreatment of C6 cells with glutathione or N-acetyl-cysteine, which are known to block the activation of neutral magnesium-dependent sphingomyelinase, inhibited ceramide formation, leading to suppression of both activation of caspase-3(-like) proteases and apoptosis by cisplatin. In contrast, pretreatment of the cells with N-oleoylethanolamine (OE), a ceramidase inhibitor, potentiated apoptosis induced by cisplatin. Furthermore, OE enhanced sensitivity of the cisplatin-resistant cells to cisplatin. These results suggest that ceramide is closely implicated in apoptosis of glioma cells by cisplatin through activation of caspase-3(-like) proteases.     

High-dose chemotherapy with autologous stem cell rescue for children with high risk and recurrent medulloblastoma and supratentorial primitive neuroectodermal tumors

Current treatment for high risk and recurrent medulloblastoma (MB) and supratentorial primitive neuroectodermal tumors (stPNET) has a very poor prognosis in children. High dose chemotherapy (HDCT) and autologous stem cell rescue have improved survival rates. We present 19 patients (thirteen classified in the high risk group and six patients with recurrent disease) that received HDCT and autologous stem cell rescue.In the high risk group [Med Pediatr Oncol 38 (2002) 83], all patients underwent neurosurgical debulking. Standard chemotherapy was prescribed in 10 patients. Radiotherapy was given to 4 patients (all older than 4years old). In the recurrence disease group [Childs Nerv Syst 15 (1999) 498], five patients underwent surgery. Radiotherapy was given to those who were not previously irradiated. The HDCT in twelve patients consisted of busulfan 4mg/kg/day, orally over 4days in 6-hourly divided doses and melphalan at a dose of 140mg/m²/day by intravenous infusion over 5min on day –1. Three patients additionally received thiotepa 250mg/m²/day intravenously over 2days and four patients additionally received topotecan 2mg/m²/day over 5days by intravenous infusion over 30min. The other seven patients received busulfan and thiotepa at the same doses.Patients stem cells were mobilized with granulocyte colony-stimulating factor at a dose of 12g/kg twice daily subcutaneously for four consecutive days. Cryopreserved peripheral blood progenitor cells were re-infused 48h after completion of chemotherapy. With a median follow-up of 34months (range 5–93) eight complete responses and one partial response were observed. Three patients died of treatment-related toxicities (15%). The 2 year event-free survival was 37.67±14% in all patients and 57±15% for the high risk group.Therefore we conclude that HDCT may improve survival rates in patients with high risk/recurrent MB and stPNET despite treatment toxicity.     

Hair product use and the risk of breast cancer in young women

Objectives: The reported mutagenic and carcinogenic effects of some chemicals present in hair dyes have raised concern that hair dye use could increase breast cancer risk. This case–control study evaluated how detailed aspects of hair coloring and hair spray application by reproductive-age women may affect breast cancer risk.Methods: Cases were white female residents of three counties of western Washington state 45 years of age or less, who were diagnosed with breast cancer between 1983 and 1990 (n=844). A sample of similarly aged women residing in the same counties served as controls (n=960). Information on hair coloring and hair spray use, as well as other exposures, was ascertained during in-person interviews.Results: Breast cancer cases were slightly more likely than controls to report ever having used some type of hair coloring application, including use of rinses, semi-permanent or permanent dyes, as well as bleaching then dyeing or frosting their hair (relative risk [RR]=1.3, 95% CI=1.0–1.6, adjusted for age, fullterm pregnancies, family history of breast cancer, and weight). In subgroup analyses, women with exclusive use of just one of these methods of hair coloring application had no elevation in risk (similarly adjusted RR=1.1, 95% CI=0.9–1.3), whereas women who used two or more of these methods did have an elevated risk (RR=1.9, 95% CI=1.4–2.5). Hair spray use was not related to the risk of breast cancer (ever versus never users: RR=1.0, 95% CI=0.8–1.3).Conclusion: The lack of an association between exclusive use of a single type of hair coloring application and breast cancer risk argues that hair coloring application does not influence breast cancer risk among reproductive-age women. Thus, the results of the present study, as well as negative ones from most (but not all) prior studies, are most consistent with the conclusion that neither hair coloring application nor hair spray application influences breast cancer risk.     

Inflammatory Breast Cancer Survival: The Role of Obesity and Menopausal Status at Diagnosis

No previous studies have evaluated the effect of body size and menopausal status at diagnosis on survival from inflammatory breast cancer (IBC). We evaluated whether obesity and menopausal status had an impact on IBC survival in a cohort of 177 female IBC patients seen from 1974 to 1993 at The University of Texas MD Anderson Cancer Center. Survival time was defined as time from diagnosis until death or censorship at last date of contact. We categorized women by body size by using the National Institutes of Health/National Heart, Lung, and Blood Institute's definitions of obesity as body mass index ((BMI)=weight in kg/(height in m)²)30, overweight as 25BMI <30kg/m², and normal/lean as BMI <25kg/m². Cox proportional hazards analysis, adjusting for axillary lymph node involvement and chemotherapy protocol, revealed a modifying effect of menopausal status at diagnosis on the association between obesity and IBC survival (P=0.02). Relative to postmenopausal women, premenopausal women had significantly worse survival (hazard ratio (HR)=1.51, 95% confidence interval (CI)=1.03–2.22). After stratifying by menopausal status, premenopausal obese women had non-significantly better survival than their leaner premenopausal counterparts (HR=0.63, 95% CI=0.34–1.15) while postmenopausal obese women had significantly worse survival than their leaner counterparts (HR=1.86, 95% CI=1.02–3.40). These findings suggest that factors associated with larger body size at diagnosis may contribute to shorter IBC survival among postmenopausal women but not premenopausal women, who were found to have poorer survival regardless of body size.     

Effect of Dose and Infusion Time on the Delivery of p-boronophenylalanine for Neutron Capture Therapy

Clinical trials of boron neutron capture therapy (BNCT) for glioblastoma multiforme are currently in progress using p-boronophenylalanine (BPA) as the 10B delivery agent. Enhancement of tumor boron uptake and/or the tumor-to-blood (T:B) boron concentration ratio would have the potential of significantly improving the therapeutic gain of BNCT. The effects of total dose, infusion time, and route of administration of BPA on tumor and blood boron concentrations were studied in rats bearing the 9L gliosarcoma. Increasing the total dose of BPA from 250 to 1000mg/kg, administered intravenously over a 2-h infusion period, resulted in an increase in tumor boron concentration from 30 to 70µg 10B/g, with a constant T:B boron concentration ratio of about 3.7:1. Similarly, extension of the infusion time from 2 to 6h, at a constant dose-rate of 125mg BPA/kg/h, resulted in an increase in tumor boron concentration from 30 to 80µg 10B/g, while, again, maintaining a constant T:B ratio of about 3.7:1. In contrast, intracarotid infusion of BPA for 1h at a dose rate of 125mg BPA/kg resulted in an increase in the tumor boron concentration from 26 to 38µg 10B/g with a corresponding increase in the T:B ratio from 3.5:1 to 5.0:1. The effects of these results on the therapeutic gain potentially achievable with BNCT are discussed.     

Progression of Premalignant MCF10AT Generates Heterogeneous Malignant Variants with Characteristic Histologic Types and Immunohistochemical Markers

The purpose of this study was to evaluate the pain experience of women during mammography for breast cancer screening. Possible associations with personal and medical history, sociodemographics and/or situational factors were studied. It was also investigated whether this pain influenced the intention to return for future breast cancer screening. In the Netherlands, women between 50–75 years are invited for screening every two years. A total of 1200 participants were asked to fill up a questionnaire. The response rate was 79.5% (n=954), and 945 questionnaires contained adequate information for analyses. A total of 689 women (72.9%) described mammography as mild to severely painful. In this group, compared to the group that reported no pain, the following factors occurred significantly more often: sensitive breasts (P=0.001), family history of breast diseases (P=0.017), expected pain based on former mammography (P=0.001), high education (P=0.008), anxiety (P=0.001), breast sensitivity in last three days (P=0.001), insufficient attention of technologist (P=0.001). Other factors like age, hormonal status, breast size and hormone use were not associated with the pain experienced. Thirty-two women (3.3%) indicated that they would not attend further screening, 25 (2.6%) reported that the pain might deter them, six women (0.6%) had other reasons, one woman (0.1%) was sure not to come because of severe pain. In conclusion, a large majority of women attending breast cancer screening describes mammography as painful (72.9%). Factors associated with pain were described. Relatively few women (2.7%) indicated that the pain might deter them from future mammography. Recommendations are given to reduce the pain experienced during screening mammography.     

Tolerance of the Normal Canine Brain to Epithermal Neutron Irradiation in the Presence of p-boronophenylalanine

Twelve normal dogs underwent brain irradiation in a mixed-radiation, mainly epithermal neutron field at the Brookhaven Medical Research Reactor following intravenous infusion of 950mg of ¹⁰B-enriched BPA/kg as its fructose complex. The 5 × 10cm irradiation aperture was centered over the left hemisphere. For a subgroup of dogs reported previously, we now present more detailed analyses including dose–volume relationships, longer follow-ups, MRIs, and histopathological observations. Peak doses (delivered to 1cm³ of brain at the depth of maximum thermal neutron flux) ranged from 7.6Gy (photon-equivalent dose: 11.8Gy-Eq) to 11.6Gy (17.5Gy-Eq). The average dose to the brain ranged from 3.0Gy (4.5Gy-Eq) to 8.1Gy (11.9Gy-Eq) and to the left hemisphere, 6.6Gy (10.1Gy-Eq) to 10.0Gy (15.0Gy-Eq). Maximum tolerated threshold doses were 6.7Gy (9.8Gy-Eq) to the whole brain and 8.2Gy (12.3Gy-Eq) to one hemisphere. The threshold peak brain dose was 9.5Gy (14.3Gy-Eq). At doses below threshold, some dogs developed subclinical MRI changes. Above threshold, all dogs developed dose-dependent MRI changes, neurological deficits, and focal brain necrosis.     

Differential Effect of Cycloheximide on Neuronal and Glioma Cells Treated with Chemotherapy and Radiation

Dividing cells and non-dividing cells are distinct in their cell cycle kinetics, and react differently when facing cytotoxic stimuli. A protein synthesis inhibitor, cycloheximide (CHX), has recently been found to protect neuronal cells from oxidative stress. We investigated whether CHX exerts differential effects on dividing and non-dividing cells in the brain under cytotoxic stimuli. Mitotic C6 rat glioma cells and postmitotic neuronal cells were studied with a cytotoxic regimen combining -irradiation (RT) and 1,3-bis,2-chloroethyl-1-nitrosurea (BCNU). Cells were exposed to BCNU (1µg/ml) for 15h before -irradiation and incubated with CHX (1µg/ml) from 30min before and until 5h after irradiation. Clonogenic assay was used to assess cytotoxic effects on C6 glioma cells. LDH assay was used for the viability of H19-7 postmitotic neuronal cells. A 2.27–3.75 fold enhancement of cytotoxicity was noticed with the addition of CHX to BCNU and 2–10Gy of radiation. Our data demonstrated that CHX enhanced cytotoxocity of RT plus BCNU, while no additional toxicity was incurred to the postmitotic neuronal cells when CHX was added. We further studied whether the inhibition of DNA repair, assayed by single-cell DNA electrophoresis (comet assay), is a contributing factor for the enhanced cytotoxicity on C6 glioma cells.Interestingly, the initial DNA damage after RT plus BCNU was equivalent; whereas DNA repair was significantly less at 5h after radiation in CHX-treated C6 glioma cells. Protecting non-dividing neuronal cells to avoid excesive functional deficit is an integral part of a successful brain tumor treatment regimen. Taking advantage of the differential effect of CHX on glioma and neuronal cells may improve tumor control without excessive neural toxicity.     

Impact of videotaped information on frequency and confidence of breast self-examination

Background Videotaped education materials to teach breast self-examination (BSE) are used worldwide. However, evaluation of videotaped BSE instructions is lacking. Methods Premenopausal women (mean age 33.4±11.2 years) without history of breast cancer were approached to participate in this experimental study and randomly assigned to a video intervention group (VG; n=130; length of the video=15 min) or non-video comparison group (NVG; n=121). All participants answered a questionnaire on BSE behavior and health beliefs. No additional training was given. The total duration of the session including completion of the questionnaire was 15min for the NVG and 30min for the VG. Three months later, changes in BSE behavior were compared in the two groups. The influence of health beliefs on actual BSE behavior was investigated as well. Results Women of both the VG and NVG performed BSE significantly more frequently at follow-up than at baseline. Analysis of covariance, using the baseline BSE-frequency as co-variate and the follow-up BSE frequency as the dependent variable, revealed that women in the VG (adjusted mean=7.9 times per year, 95%CI=6.5–9.4) performed BSE more frequently than women of the NVG (adjusted mean=6.1 times per year, 95%CI=4.6–7.5) (F=4.2, df=2, p=0.02). Among motivational predictors, having an example of a role model (modeling) was shown by regression analysis to explain the greatest amount of variance (13%) in BSE frequency. Conclusion Use of an educational videotape increased the frequency of BSE among premenopausal women.     

A prospective study of plasma ascorbic acid concentrations and breast cancer (United States)

Objectives:To investigate the association between prediagnostic plasma ascorbic acid concentrations and subsequent breast cancer risk in a nested case–control study. Methods:Female volunteer residents of Washington County, MD, donated 14,625 non-fasting blood samples in 1989. Incident breast cancer cases (n=115) and controls (n=115) were matched by age, menopausal status at donation, and date and hour of blood donation. Results:Median ascorbic acid concentrations were similar between cases and controls (1.44mg/dl vs. 1.39mg/dl, p=0.78). There was no evidence for a dose–response relationship between higher plasma ascorbic acid concentrations and breast cancer risk [highest vs. lowest fifths: OR_adjusted=0.90, p _trend=0.98). Conclusions:Findings from this prospective study do not suggest a protective association between prediagnostic plasma ascorbic acid concentrations and breast cancer risk in the subsequent 5years of follow-up.     

Low body mass index is an independent predictive factor of local recurrence after conservative treatment for breast cancer

Background. Obesity or increased body mass index (BMI) has been shown to have two important adverse effects related to breast cancer. First, several studies have identified an association between increased BMI and advanced stage breast cancer. Second, increased BMI has been shown to be associated with poorer prognosis. In a previous report, we had identified low BMI as a risk factor for local reccurence at five years. The objectives of this study were to evaluate the relationship between BMI and local control and to confirm this prognostic factor in a larger population with an important follow-up. Materials and methods. Between 1976 and 1988, 605 women with invasive breast carcinoma less than 4cm in diameter underwent conservative surgery with axillary dissection and radiation therapy. The median follow-up time was 82 months. The risk of local recurrence and distant metastasis was evaluated by univariate retrospective analysis using Kaplan–Meier method for the main clinical and histologic factors. Those found to be significant were entered in a Cox model for multivariate analysis. Results. Since the beginning of the study, 80 patients had developed local recurrence. The 5 years and 10 years local control rates were 91% and 83%, respectively. Four parameters were independent predictive factors of local recurrence: Age lower than 40 years (HR=2.42 95% CI=[1.35–4.34]), BMI: elevation of one unit reducing the local recurrence of 0.92 95%CI=[0.85–0.99], multifocality of the tumor on pathological examination (HR=2.12 95% CI=[1.16–3.88]) and positive axillary nodes HR=0.54 95% CI=[0.31–0.95]. Size of the breast was not a predictive factor for local cancer recurrence. Low BMI did not increase risk of distant. Conclusion. Our study offers new data concerning the possibility that thinness may be related to local recurrence of breast cancer.     

Infertility and risk of fatal ovarian cancer in a prospective cohort of US women

Objectives: It is difficult to separate the possible role of fertility drugs from underlying infertility as risk factors for ovarian cancer. The present study examined the relationship between self-reported infertility and death from ovarian cancer among married women unlikely to have been exposured to fertility drugs.Methods: Women were selected for study from the 676,526 female participants in Cancer Prevention Study II (CPS-II). After twelve years of follow-up, 797 deaths from ovarian cancer were observed among women with no prior history of cancer or hysterectomy and 40 years of age or older in 1967 when ovulatory stimulants were approved in the United States. Cox proportional hazards modeling was used to compute rate ratios (RRs) and to adjust for other potential risk factors.Results: Overall, self-reported infertility was not significantly associated with ovarian cancer mortality (adjusted rate ratio (RR)=1.1, 95 percent confidence interval (CI)=0.9-1.3). Ovarian cancer death rates among nulligravid women with self-reported infertility, however, were 40 percent higher than for nulligravid women who never tried to become pregnant (RR=1.4, 95 percent CI=0.9-2.4). Multigravid women who reported infertility problems were not at increased risk.Conclusions: These results suggest that infertility itself, without concomitant exposure to fertility drugs, may increase risk of fatal ovarian cancer among nulligravid women.     

Alcohol consumption and risk of breast cancer: a cohort study

Objectives: To study the association between alcohol consumption and breast cancer risk. Methods: A case–cohort analysis was undertaken within the cohort of 56,837 women who were enrolled in the Canadian National Breast Screening Study (NBSS) and who completed a self-administered dietary questionnaire. (The NBSS is a randomized controlled trial of screening for breast cancer in women aged 40–59 at recruitment.) The cohort was recruited between 1980 and 1985, and during follow-up to the end of 1993 a total of 1469 women in the dietary cohort were diagnosed with biopsy-confirmed incident breast cancer. For comparative purposes a subcohort consisting of a random sample of 5681 women was selected from the full dietary cohort. After exclusions for various reasons the analyses were based on 1336 cases and 5238 noncases. Results: When compared to nondrinkers the adjusted incidence rate ratios (95% confidence intervals) for those consuming>0 and 10g of alcohol/day, >10 and 20g/day, >20 and thinsp;30g/day, >30 and 40g/day, >40 and 50g/day, and >50g/day were 1.01 (0.84–1.22), 1.16 (0.91–1.47), 1.27 (0.91–1.78), 0.77 (0.51–1.16), 1.00 (0.57–1.75), and 1.70 (0.97–2.98), respectively; the associated p value for the test for trend was 0.351. Similar findings were obtained when analyses were conducted separately in the screened and control arms of the NBSS, in premenopausal and postmenopausal women, for screen-detected and interval-detected breast cancer, and by levels of other breast cancer risk factors. Conclusions: The results of this study suggest that alcohol consumption might be associated with increased risk of breast cancer at relatively high levels of intake.     

Ultrastructural Changes of the Vascular Endothelium after Intra-arterial Administration of Tumor Necrosis Factor-alpha (TNFα) in Rat Gliomas

The ensuing ultrastructural changes in tumor vascular endothelial cells following intra-arterial administration of tumor necrosis factor- (TNF) were studied in an experimental rat glioma model. C6 glioma cells were implanted in Wistar rats and then after 14 days, 5×10³U of human natural-type TNF (1.7×10⁵U/m²) was administered through the carotid artery. The animals were sacrificed at 3 or 24h after TNF treatment. A detailed examination with transmission electron microscope revealed swelling of the tumor vascular endothelial cell nuclei and mitochondria with matrix densities at 3h. At 24h, these cells demonstrated the presence of high amplitude mitochondrial swelling or the violent blebbing characteristic of damaged mitochondria; the cytoplasm was swollen enormously and there were dissolution of cytoplasmic organelles and rupture of the plasma membrane. The observed findings were typical of cell necrosis and confirms yet another mechanism by which TNF exerts its anti-tumor effects, that is, necrotizing effects on tumor vascular endothelium. The information appears to be important in the context of clinical application of intra-arterial TNF in the treatment of malignant gliomas.     

Increased risk of second cancers following breast cancer: Role of the initial treatment

Objectives and methods.The risk of second primary malignancies (SMN) was studied in a cohort of 4,416 one-year survivors of a breast cancer. The role of the menopausal status and of the initial treatment modalities (surgery, radiotherapy, and chemotherapy) was investigated. Results.Excluding second primary breast cancer and non-melanoma skin cancer, a total of 193 (4.4%) patients developed a SMN between 1973 and 1992, compared with 136 expected (Standardised Incidence Ratio, SIR=1.4, 95% CI (1.2–1.6)). No trend towards either an increase or a decrease was noted in the SIR with time after treatment (p=0.2). The greatest increase in the relative risk concerned soft tissue cancers (SIR=13.0, 95% CI: 6.8–22.3), followed by leukaemia (SIR=3.1, 95% CI: 1.7–5.0), melanoma (SIR = 2.7, 95% CI: 1.4–4.8), kidney (SIR=2.5, 95% CI: 1.2–4.5), ovary (SIR=2.0, 95% CI: 1.2–3.1) and uterine tumours (SIR=1.9, 95% CI: 1.4–2.5). The SIR was 3.0 (95% CI 1.8–4.7) in women under 40 at the time of the breast cancer, 1.9 (95% CI : 1.4 – 2.4) in those aged 40–49 and 1.2 (95% CI 1.0–1.4) in those aged 50 or more. In the 2,514 women who had received radiotherapy as initial treatment without chemotherapy, the SIR for all SMN was 1.6 (95% CI: 1.1–2.3) fold higher than in those who had not received radiotherapy as initial treatment. Conclusion.In conclusion, this study confirms the increased risk of second malignancies in women treated for a breast cancer, and particularly in those who were younger at the time of treatment for breast cancer. Our results also suggest that radiotherapy may play a role in the onset of these second lesions.     

Prevention of rat mammary carcinoma utilizing leuprolide as an equivalent to oophorectomy

A clinical trial is currently under way to examine the effectiveness of leuprolide as a breast cancer chemopreventive agent and contraceptive. This trial, as well as similar proposed studies, is based on the assumption that leuprolide is as effective as surgical castration in preventing the onset of mammary tumors; however, this has not been well documented in the DMBA animal model. We directly compared leuprolide and oophorectomy in this model and examined a combined therapy of leuprolide/bromocriptine. Twenty-seven day old female Sprague-Dawley rats were randomly allocated into one of eight groups. All rats received a 20-mg dose of DMBA at the age of 55 days. Group 1 (n=10), no treatment; Group 2 (n=9), leuprolide (100g/kg/day) for eight weeks beginning four weeks prior to DMBA; Group 3 (n=10), oophorectomy four weeks prior to DMBA with replacement estrogen beginning four weeks following DMBA. Estrogen replacement was achieved with a 0.05-mg estradiol tablet releasing 0.833g/day over a 60-day period. Group 4 (n=10), leuprolide (100g/kg/day) initiated two weeks prior to DMBA and continuing for two weeks following DMBA; Group 5 (n=9), oophorectomy two weeks prior to DMBA with 0.05mg of estradiol in depot form, releasing 0.833g/day, beginning four weeks following DMBA and continuing until week 16 of the study; Group 6 (n=10), leuprolide (100g/kg/day) beginning two weeks prior to DMBA and continuing for the duration of the experiment; Group 7 (n=10), leuprolide (100g/kg/day) for eight weeks beginning two weeks prior to DMBA; Group 8 (n=9), leuprolide (100g/kg/day) and bromocriptine (83g/day) for eight weeks beginning two weeks prior to DMBA. At nineteen weeks (15 weeks post DMBA), animals were sacrificed and autopsies performed. One hundred percent of untreated animals developed tumors. No animals undergoing oophorectomy four weeks prior to DMBA or receiving leuprolide four weeks prior to and simultaneously with DMBA developed tumors. In animals pretreated two weeks prior to DMBA with leuprolide or oophorectomy, each group had one animal with tumor development. No tumors developed in the animals receiving ongoing injections of leuprolide. However, one tumor developed in those receiving leuprolide for the first eight weeks beginning two weeks prior to DMBA administration. One animal receiving both leuprolide and bromocriptine developed one tumor. We conclude that chemical oophorectomy (with leuprolide) is as effective as surgical oophorectomy in inhibiting DMBA induced carcinogenesis.     

Effect of the aromatase inhibitor vorozole on estrogen and progesterone receptor content of rat mammary carcinomas induced by 1-methyl-1-nitrosourea

Vorozole, a nonsteroidal aromatase inhibitor, impedes the post-initiation stage of chemically induced mammary carcinogenesis. While various aspects of vorozole's effects on mammary carcinoma development have been investigated, little attention has been directed to determining the estrogen receptor (ER) and progesterone receptor (PR) content of mammary carcinomas that arise despite vorozole treatment. Female Sprague–Dawley rats were given an i.p. injection of 50mg MNU/kg body weight at 21 days of age and placed on diet supplemented with 0 or 3mg vorozole/kg, which had no effect on mammary tumor development. Histologically confirmed carcinomas were evaluated for ER and PR by immunohistochemistry. In the control group, 78.8% of carcinomas were ER positive with an ER content ranging from 13.8 to 40.0%, similar to ER content of mammary ductal epithelial cells from non-carcinogen treated animals. PR content ranged from 4.4 to 45.2% and also was similar to levels of PR observed in ductal epithelial cells. ER was not correlated with PR in mammary carcinomas (r=0.05, p>0.80), whereas there was a significant correlation in ductal epithelium (r=0.86, p=0.006). In vorozole-treated rats, no ER negative carcinomas were observed and overall ER expression by vorozole was elevated (p<0.03). All carcinomas from vorozole-treated rats expressed PR (2.5–60.2%) and correlation between ER and PR content was numerically greater in carcinomas from vorozole-treated animals (r=0.42, p=0.09). These data, which are considered hypothesis generating, provide evidence that low doses of vorozole in the diet select for mammary carcinomas with an increased ER positive phenotype.     

Flow cytometric analysis of primary tumors and their corresponding metastatic nodes in breast cancer

Human breast carcinoma is biologically heterogeneous, and its clinical course may vary from one which is indolent to one which rapidly progresses. Although it is the metastasis rather than the primary tumor that ultimately overwhelms the patients, studies concerning the DNA pattern have focused on the primary tumors. This study was undertaken to identify heterogeneities between primary tumors and metastases, and to evaluate the prognostic significance of the ploidy pattern and the S-phase fraction (SPF) of metastatic nodes in axillary node positive patients. Seventy-four frozen specimens of the primary and corresponding metastatic nodes from 37 patients have been analyzed by flow cytometry and the SPF calculated. The results of ploidy pattern analysis in primaries revealed 25 diploidy (67.6%) and 12 aneuploidy (32.4%), while those in metastasis showed 17 diploidy (46.0%) and 20 aneuploidy (54.0%). The aneuploidy group in metastatic nodes had the poorer histological grade (85.0% vs. 15.0%, p=0.02), and more mean metastatic nodes (5.75±2.10 vs. 3.05±1.56, p=0.018), and more frequent lymphatic vessel invasion (65.0% vs. 11.8%, p=0.031) than its counterpart. Decreased expression of ER (70.6% vs. 25.0% p=0.006) and increased expression of c-erbB2 (65.0% vs. 23.5%, p=0.012) were observed in the aneuploidy of metastatic nodes. The group with higher SPF in metastatic nodes had more metastatic nodes (5.47±2.31 vs. 4.00±1.78, p=0.042), and the higher incidence of lymphatic vessel invasion (57.9% vs. 22.2%, p=0.027), and poor histological grade (71.4% vs. 37.5%, p=0.039). In conclusion, the cell populations in metastatic nodes revealed DNA pattern which differed from that of primary tumors. The ploidy pattern and SPF in metastatic nodes might be considered as discriminate measure for risk factors in breast cancer patients with positive axillary node.