Prognostic significance of preoperative MRI scans in glioblastoma multiforme

Tumor necrosis, enhancement, and associated edema in patients with glioblastoma multiforme (GBM) represent biological variables that can be quantitated on preoperative MRI scans. We reviewed 48 highly selected patients, all of whom had supratentorial lesions, had undergone gross total tumor resection, and had received adjuvant treatments (radio- and chemotherapies). None of these patients had had surgery for recurrent tumor resection and none had harbored multifocal tumors. The median age was 50 years. The median Karnofsky performance score was 80. Multivariate analysis using the Cox regression model revealed that the strongest prognostic variable was the amount of tumor necrosis on preoperative scan (P < 0.001), with median survivals of 42, 24, 15, and 12 months for tumor necrosis grades of 0 (7 pts), I (11 pts),11 (9 pts), and III (21 pts), respectively. The intensity of enhancement of the tumor nodule was another prognostic factor (P = 0.003), with median survivals of 35, 18, and 13.5 months for enhancement grades of 0 (2 pts), I (22 pts), and II (24 pts), respectively. The extent of peritumoral edema had a quadratic effect (P = 0.001), with grades I (19 pts), II (22 pts), and III (7 pts) surviving for 24,12, and 20 months respectively. Location and volume of tumors were not statistically significant predictors of survival (P < 0.05). In conclusion, in this highly selected group, GBM patients with little or no necrosis and with less tumor nodule enhancement on preoperative MRI survive longer than patients with greater amounts of necrosis and greater degrees of tumor enhancement. In addition, a moderate degree of peritumoral edema is associated with worse prognosis.     

Adding adjuvant CMF chemotherapy to either radiotherapy or tamoxifen: Are all CMFs alike?

The first reported effective adjuvant combination regimen for patients withoperable breast cancer comprised oral cyclophosphamide (C) days 1–14with intravenous methotrexate (M) and fluorouracil (F) on days 1 and 8,repeated every 28 days (classical CMF). These drugs have since beenextensively used with or without endocrine therapies and/or other cytotoxics,as well as with radiation therapy to the chest wall yielding conflictingresults. Although doses and schedules have varied widely, the combination ofthese three drugs has been generically referred to as CMF. Evidence existsthat reducing the dose and/or altering the schedule of CMF (modified CMF)have compromised its efficacy in metastatic breast cancer. Reduction belowstandard dose of a similar regimen also gave inferior results in the adjuvantsetting. In fact, the recently reported improved outcome of adding radiationtherapy to CMF was only demonstrated in comparisons with a modified CMF.Furthermore, trials in women with estrogen receptor-positive breast cancer,which did not demonstrate any significant benefit for the addition of adjuvantCMF to tamoxifen compared with tamoxifen alone, also used modified CMF.Therefore, adherence to the classical dose and schedule is recommended whenCMF is used in adjuvant therapy.     

Metachronous seeding of lymph node metastases in rats bearing the MT-100-TC mammary carcinoma: The effect of elective lymph node dissection

Summary Following the introduction of cancer cells into the lymphatic system, metastases in down-stream lymph nodes often appear in a sequential manner. This could be due to synchronous seeding of the in-line nodes with progressively diminishing numbers of tumorigenic cancer cells, or alternatively, by discrete, stepwise (metachronous) seeding of down-stream nodes by up-stream nodal metastases acting as generalizing sites. Metachronous seeding to local lymph nodes is potentially curable by elective lymph node dissection; synchronous seeding is not.Synchronous versus metachronous seeding of lymph node metastases was investigated using the MT-100-TC mammary carcinoma injected into the hind foot-webs of rats. When the primary tumor was removed by amputation one week after injection, 1/15 animals survived; in contrast, removal of the draining popliteal lymph node in addition to the primary lesion, resulted in 8/19 long-term survivors. At this time, occult metastases detectable by bioassay butnot by conventional histology, were present in all draining popliteal nodes and in 60 percent of lungs. The fact that some amputees were cured when the popliteal node was removed, indicated the metachronous nature of nodal metastases in this system. Further, recurrence of nodal and lung metastases in those amputees in which the popliteal node was left intact, identified the popliteal node as a generalizing site. By the time popliteal node involvement was evident by conventional histology, micrometastases were present in down-stream nodes, and accordingly, removal of the popliteal node and the primary lesion at this time was not curative.     

Exploratory study of drug plasma levels during bicalutamide 150 mg therapy co-administered with tamoxifen or anastrozole for prophylaxis of gynecomastia and breast pain in men with prostate cancer

Objective:A randomized multicenter (14 centers) trial was conducted in 114 men with prostate cancer to determine whether the antiestrogen tamoxifen (Nolvadex) 20 mg or the aromatase inhibitor anastrozole (Arimidex) 1 mg prevent gynecomastia and breast pain during treatment with the non-steroidal antiandrogen bicalutamide (Casodex) 150 mg, without compromising efficacy, safety, or quality of life. Plasma samples were collected in a subgroup of these patients to investigate whether trough (pre-dose) concentrations of bicalutamide 150 mg are influenced by concomitant administration of tamoxifen 20 mg or anastrozole 1 mg; the results of this pilot study are reported in this article. Methods: A subpopulation of patients from a randomized placebo-controlled trial evaluating tamoxifen 20 mg and anastrozole 1 mg for the prevention of gynecomastia and breast pain in men receiving bicalutamide 150 mg for early or recurrent prostate cancer were selected on a voluntary basis from three of the trial centers. Plasma samples were collected on days 7, 14, 28, and 84 of therapy and analyzed to determine the plasma concentrations of (R)–bicalutamide and (S)-bicalutamide. In addition, plasma concentrations of tamoxifen, N–desmethyltamoxifen, and anastrozole were determined. Results: A total of 21 patients were selected. There was no significant difference between treatment groups with respect to the trough plasma concentrations of either bicalutamide enantiomer at any point during the study. Plasma concentrations of the enantiomers, and the relative proportion of the ®)- and (S)–enantiomers, were consistent with those reported in previous studies. Plasma concentrations of tamoxifen, N–desmethyltamoxifen, and anastrozole were also similar to those described elsewhere in the literature. Conclusions: The findings of this pilot study suggest that trough plasma concentrations of bicalutamide enantiomers following administration of bicalutamide 150 mg are not markedly influenced by concomitant administration of tamoxifen 20 mg or anastrozole 1 mg. However, an effect of tamoxifen on bicalutamide pharmacokinetics can not be completely excluded due to the size of this study. Further studies are needed to clarify the effect of tamoxifen on bicalutamide pharmacokinetics and prostate cancer control in bicalutamide-treated patients. Arimidex, Casodex, and Nolvadex are trademarks of the AstraZeneca group of companiesThis trial was sponsored by AstraZeneca (Milan, Italy)     

A phase II study to evaluate the combination of fludarabine, mitoxantrone and dexamethasone (FMD) in patients with follicular lymphoma

Background:Molecular response is being investigated as atherapeutic goal in follicular lymphoma (FL). High response rates in FL withthe fludarabine combination FMD have been associated with molecularremission. A phase II study of FMD in FL was therefore conducted. Patients and methods:Fifty-four patients, ten of whom were newlydiagnosed received FMD. Forty-four percent of the previously treated patientshad chemoresistant disease. Treatment comprised: fludarabine 25mg/m² days 1–3, mitoxantrone 10 mg/m² day 1, anddexamethasone 20 mg days 1–5. Blood/bone marrow was collected forquantitation of t(14;18) by real-time PCR. Results:The overall response rate was 37 of 54 (69%),complete responses being seen in 11 patients (20%), with no differencebetween newly diagnosed and the previously treated patients. However, theresponse rate in chemosensitive relapse was 84%, compared to44% in patients in whom the last prior regimen had failed. Molecularresponses were seen in 17 of 25 and PCR negativity in 8 of 25, althoughmolecular and clinical responses did not always correlate. Toxicity wasmoderate, 19 patients required admission. However, in 6 of 12 patients,subsequent G-CSF mobilised stem cell harvests failed. Conclusions:FMD was well tolerated but with a lower than expectedresponse rate. Molecular responses were seen in the majority of respondingpatients however, molecular remission was rare.     

On the development of an interstitial radiation protocol for a multicenter consortium. Experience with permanent low-dose rate and temporary high-dose rate125I implants in ‘failed’ and ‘newly diagnosed’ glioblastoma patients: Quality assurance methodology and a possible future adjuvant for therapeutic enhancement

Summary Three interstitial implant trial groups (one permanent low-dose rate¹²⁵I and two temporary high-dose rate¹²⁵I implants) in glioblastoma patients (newly diagnosed and failed) were compared to non-randomized similar control groups for efficacy. The results formed the basis for the BTCG 87-01 national implant trial. The pilot trial demonstrated: 1) the effectiveness of a temporary high-dose rate¹²⁵I implant in failed and newly diagnosed patients; 2) the ability of a multicenter consortium to adhere to a standard protocol; 3) a methodology to insure quality assurance; and 4) the possibility of the future adjuvant application of hyperthermia using a single catheter system.     

Intermittent Blood Flow in Solid Tumours – an under-appreciated Source of ‘drug Resistance’

As the search for improved anti-cancer drugs continues, new paradigms concerning the reasons for clinical failures in common human solid tumours are also evolving. Classical drug resistance is now perhaps less often invoked to explain lack of treatment efficacy than are newer concepts, including contact resistance, tumour heterogeneity, regrowth resistance, and physiological barriers to drug delivery. This commentary will explore the resistance of solid tumours to chemotherapy from yet another, largely ignored perspective: that of tumour-specific fluctuations in blood flow. Transient decreases in blood flow have significant implications for delivery of chemotherapeutic agents, cellular responsiveness to those agents, and the regrowth potential of the surviving tumour cells.     

A sequential cell kinetic study of meningioma cells in primary explant culture using bromodeoxyuridine

The present study was undertaken to evaluate the sequential BrdU-LI at weekly intervals upto four weeks in 18 primary explant cultures of meningiomas. This revealed three distinct patterns of growth which could be arbitrarily defined as degenerating (group I), proliferating (group II) and adaptive (group III) types. Interestingly two cases of malignant and two of recurrent meningiomas fell into the degenerating group I pattern. The possible explanations for the observed relatively higherin vitro LI values compared to lowerin vivo values as reported in the literature and the theoretical implications of the three distinct patterns of sequential LI values are discussed.     

START: A European state-of-the-art on-line instrument for clinical oncologists

START (State-of-the-Art Oncology in Europe), a freely available resource on the Internet, is a European information base of current clinical approaches to human tumours. Its aim is to help clinical oncologists make appropriate clinical decisions by providing them with updated information reflecting state-of-the-art cancer treatment as perceived by the European oncology community. It is based upon contributions from authors and internal reviewers from all over Europe as selected by START's editorial board under the supervision of an advisory board and a scientific committee. Close collaborations with the main European cancer societies are ongoing. An external feedback process augments the mechanisms for rendering START a truly European instrument. START is concerned with evidence-based cancer medicine, and the main clinical options are thus codified and their bases indicated in accord with a scale worked out from the perspective of clinical decision-making. Therapeutic options may be standard, investigational, or suitable for individual clinical use (within the context of a decision made jointly by the patient and the physician). The goal of instruments such as START is to improve the quality of patient care. In addition, START hopes to make contributions to the methodology by which medical research is transformed into clinical decisions.     

Mitotic rate,DNA distribution,and chromatinin situ sensitivity to heparin in breast cancer

Summary The purpose of this study was to characterize breast carcinomas by cell kinetic parameters. Mitotic rate (MR) and flow cytometrically (FCM) measured cell cycle distribution as well as chromatin testing in situ employing heparin for determination of activated chromatin, provided the following results:MR counted in 73 unselected carcinomas showed an increase up to a tumor size of 4.2cm (p < 0.05); beyond this diameter, the MR was found to decrease.In T1-T2 carcinomas, cell cycle stage analysis yielded higher percentages of cells in S and G₂M phase for ductal (13% and 12%, N = 22) than for lobular (8% and 7%, N = 8) node-negative carcinomas (p < 0.002). In ductal carcinomas, lymph node involvement was reflected by higher % G₂M values (15%, N = 26) compared with negative cases (12%, N = 22) (p < 0.05).Ductal node-positive T3-T4 carcinomas (N = 10) revealed a higher % S value (16%) than their T1-T2 counterparts. A correlation between MR and % G₂M was established only up to a tumor size of 4.2 cm (r = 0.39, p < 0.05).A highly sensitive (H) and a poorly sensitive (P) subgroup of carcinomas with respect to heparininduced changes in fluorescence intensity of the G_1/0 peak of the DNA aneuploid cell line were identified, as previously shown [1]. These subgroups were here updated with a larger number of carcinomas and were limited to T1-T2 cancers (N = 57). Group H included more younger patients (p < 0.005), less cases with nodal involvement in ductal carcinomas (p < 0.05), and lower % G₂M values in lobular node-negative cases (p < 0.05), than group P. DNA diploid cells always existing in DNA aneuploid carcinomas are more sensitive than their aneuploid counterparts (p < 0.01); however, they strengthen the stratification to H and P. We suggest H carcinomas to be less aggressive than P carcinomas. Small breast carcinomas are recommended to cell kinetic investigations for individualizing adjuvant therapy.     

Pediatric Medulloblastoma: Prognostic Value of p53, bcl-2, Mib-1, and Microvessel Density

The aim of this study was to retrospectively assess the prognostic value of p53 and bcl-2 protein expression, cell proliferation index (Mib-1 index), and tumor microvessel density (factor VIII-related antigen) in pediatric medulloblastoma patients. Tumor specimens of 55 patients (age 2–18 years) with medulloblastoma treated with a curative intent between 1972 and 1991 were studied. Slides of paraffin embedded tissue were stained with monoclonal antibodies (mAb) and examined under high power light microscopy for the presence of immunoreactivity. Microvessel density was scored both in the area of most intense staining (Angio-max) and in 3 additional randomly selected areas. The sum of these 4 scores was termed Angio-total. Angio-max and Angio-total were evaluated separately by two independent investigators to assess reproducibility. None of the parameters studied, i.e. p53 or bcl-2 expression, Mib-1 index or microvessel density scores were associated with patient survival. Microvessel scores between observers were significantly but weakly correlated, with correlation coefficients (r)<0.5 for both Angio-max and Angio-total. Leptomeningeal spread at diagnosis was the only independent factor associated with a poor survival (p=0.003). There was no association of leptomeningeal metastasis with any of the biological markers tested in this study.     

EORTC 10941: A phase II study of liarozole in postmenopausal patients with ‘Chemotherapy-Resistant’ or ‘Potentially Hormone Sensitive’ metastatic breast cancer

Liarozole is an imidazole compound that inhibits enzymes involved in steroid hormone aromatisation and retinoid metabolism. The IDBBC branch of the EORTC has performed a series of phase II studies of the agent in four groups of postmenopausal women with metastatic breast cancer. This paper reports the results of the first two groups: Chemotherapy Resistant (unrestricted ER status, 1 or 2 prior chemotherapy regimens, 0–2 prior hormonal therapies) and Potentially Hormone Sensitive (ER positive or unknown, 1 or 2 prior hormonal therapies with a substantial disease free interval or progression free survival, and no history of chemotherapy for metastatic disease). Liarozole was administered at 150–300 mg orally bid. The objective response rate was 12% in the Chemotherapy Resistant group (n=34), and 22% in the Potentially Hormone Sensitive group (n=37), with median response durations of 9 and 14 months, respectively. Median time to treatment failure was only 2 months in both groups, due largely to the significant percentage (24%) of patients who ceased treatment following excessive mucocutaneous and gastrointestinal toxicity. This adverse event profile will limit its use in breast cancer. Results of the ER negative and Tamoxifen Refractory groups will be reported in a future paper.     

Cytosol and nuclear estrogen receptors (occupied and unoccupied sites) and progesterone receptors in human breast cancer

Summary Estrogen and progesterone receptor concentrations in cytosol and nucleus were measured in 21 primary breast cancer tumors. Twelve out of the 21 tumor samples were cytosol estrogen receptor positive, 8 of which contained only unoccupied estrogen binding sites in the cytosol, but 2 of the 9 estrogen receptor negative samples did contain cytosol binding sites already occupied by endogenous homone. Four other estrogen receptor negative tumors only showed nuclear binding sites. Only 3 of the 12 estrogen receptor positive tumors also contained progesterone receptors. All of these tumors also had estrogen receptor in the nucleus. However, three of the 17 progesterone receptor negative samples had progesterone receptor only in the nucleus. The present data indicate that 3 possible classes of false negative tumors can be encountered: 1) estrogen receptors occupied by endogenous hormone, 2) tumors containing only nuclear estrogen receptors, and 3) tumors having only nuclear progesterone receptors. Measurement of nuclear estrogen receptor together with the progesterone receptor provides further information on whether the estrogen receptor system is not only present but also functional, and should be of value in the prediction of hormone dependent breast cancer.     

Metallothionein-like proteins and cell resistance tocis-dichlorodiammineplatinum(II) in L1210 cells

Summary Our studies on the mechanism of resistance of the murine leukemia L1210-PDD line tocis-dichlorodiammineplatinum(II) (cis-DDP) have not shown why it is 10-fold more resistant to the drug than the L1210 line. For this reason we investigated metallothionein-like proteins (MTs) in these cells. Soluble protein extracts from cultures treated for 24 h withcis-DDP, zinc sulphate or saline were anaerobically eluted from columns of chemically reduced Sephadex G-75, and the profiles of zinc, copper and platinum were determined along with those for incorporated radioactive cyst(e)ien and tyrosine. Both salinetreated cell lines contained similar levels of MTs, which were induced by exposure to a minimally toxic level of zinc (100 M). Zinc induction of MTs was nearly 4-fold greater in L1210 than in L1210-PDD cells. The levels of mRNA for metallothionein I (MTI) and (MTII) in uninduced cells were measured by dot-blotting with a cDNA probe. The L1210-PDD cells contained 80% of the MTI and 41% of the MTII compared with L1210 cells, confirming the similar levels in uninduced cells. L1210-PDD cells were 2-fold more sensitive than L1210 cells to cadmium and equally sensitive to zinc. Thus, the resistance of L1210-PDD cells tocis-DDP was not associated with cross-resistance to group II_b metals, whereas their sensitivity to cadmium did reflect the relative inability of the cells to synthesize MTs. The L1210 cells produced MTs when treated with 0.5 and 5.0 M cis-DDP, but the L1210-DDP cells did not when treated with 5.0–40 M cis-DDP. Small amounts of platinum (<21% of the total eluted) were bound to MTs in both cell lines, but platinum provided a minor portion of the MT-bound metals, with zinc and copper contributing the bulk. The basis for the resistance of L1210-PDD cell tocis-DDP is neither an increased level of MTs in the resistant cells nor an enhanced ability to increase the synthesis of MTs after drug exposure.This work was funded from a Peter Crimmins Research Fellowship held by P. G. F.     

Impact of the axillary nodal status on sentinel node mapping in breast cancer and its relevance for technical proceeding

Objective. The aim of this study is to analyze whether the axillary status influences the lymphatic mapping procedure in malignant breast disease and whether clinically relevant consequences for the technique of Sentinel Node (SN) biopsy may be drawn from this information. Materials and methods. SN biopsy was performed in 150 consecutive patients using a combination of the radioguided and the blue-dye technique. Axillary status was compared with the number of detected nodes. In cases of numerous nodes with tracer uptake, the radioactivity of each radiolabeled node was measured separately in a dose calibrator. We analyzed whether an increased tracer uptake could possibly indicate a true or dominant SN. Blue dye uptake was registered and compared with radioactivity. The findings were related to the histologic results. Results. In patients with a positive axillary status, significantly more radiolabeled nodes were detected than in node negative patients (median 3 vs. 2; p<0.001). In 54/86 patients with numerous SNs a dominant node with at least twice the radioactivity than other marked nodes could be identified (62.8%). From 26 cases with axillary involvement, 20 patients (76.9%) were identified by the dominant and the remaining six women (23.1%) by others than the seemingly leading SN. Conclusion. Axillary lymph node involvement influences the drainage pattern in breast cancer. Patients with numerous SNs have an increased risk of axillary involvement. A high tracer uptake does not permit the identification of a true SN. A lack of surgical accuracy may lead to pitfalls if the axilla is not screened carefully for all radioactive nodes.     

Efficacy of ‘8-drugs-in-one-day’ combination in treatment of recurrent GBM patients

Summary Thirty-five adult recurrent GBM patients, divided randomly in two groups of 19 and 16 cases, had been treated with two regimens of chemotherapy: a) eight-drugs-in-one-day; b) procarbazine + CCNU + vincristine (PCV) respectively. Chemotherapy was planned at the tumor relapse and delivered as long as tolerated without irreversible sequelae or until the CT scan showed tumor progression.Multiple agents are used simultaneously in the therapeutic approach using eight-in-one to kill as many heterogeneous cells of malignant glial tumor as possible and minimize the emergence of cellular resistance to chemotherapy. Rate response to chemotherapy and the median adjunctive survival time (6.5 and 6 months, respectively) are not significantly different in the two arms of this study. Our experience with such an aggressive multi-drugs combination eight-in-one-day was disappointing if compared with less toxic, better tolerated and easy delivered (PCV) regimen.     

Genes associated with tumor suppression and growth control in the human nervous system

Cancer, the uncontrolled proliferation of a population of somatic cells, is fundamentally a genetic disorder. Although the specific array of genetic changes causing individual tumor types remains largely obscure, the past two decades have witnessed a tremendous increase in our understanding of the specific genes regulating cell differentiation, proliferation, and senescence. There appear to be two distinct fundamental genetic mechanisms of tumorigenesis. One mechanism is associated with the activation of growth-promoting factors such as proto-oncogenes. Altermatively, tumor formation may be induced as the result of the loss or inactivation of genes which normally regulate or suppress cell growth. These genes have been termed tumor suppressor genes or anti-oncogenes. This review focuses on the role of tumor suppressor genes in tumor formation and growth control of the human nervous system.     

Drug and radiation resistance in spheroids: cell contact and kinetics

Cells from multicellular spheroids are often more resistant than monolayers to drugs and radiation. While explanations for resistance can be based on differences in cell cycle distribution, inability of the drug to penetrate the spheroid, or the presence of hypoxic cells, these mechanisms do not adequately explain resistance to all agents. Small spheroids (containing about 25–50 cells) exposed to ionizing radiation, hyperthermia, photodynamic therapy, or topoisomerase II inhibitors, are more resistant to killing than monolayers; the close three-dimensional contact in spheroids has been implicated in this resistance. Proposed mechanisms for the contact effect include gap junctional reciprocity, cell shape mediated changes in (repair-related) gene expression, and alterations in chromatin packaging which influence DNA repair. The consequences of the contact effect are especially important for multifraction exposures. Another form of resistance can be demonstrated during repetitive treatments; regrowth resistance reflects the capacity of spheroid cells to proliferate more efficiently to compensate for cell killing.     

Oestrogen receptor concentration in primary breast cancer and axillary node metastases

Summary The primary tumour and 1–3 invaded, axillary nodes from each of 24 patients were examined both histologically for the proportion of the specimen constituted by malignant epithelial cells (cellularity index) and biochemically for oestrogen receptor concentration. Both malignant epithelial cell content and oestrogen receptor concentration were significantly higher in the nodal metastases than in the primary tumours, malignant cells constituting approximately half of the former tissue and three quarters of the latter. On average, receptor concentrations were 1.6 × (protein basis) to 2.3 × (wet weight basis) higher in nodes than in the primary tumours, probably due at least in part to the difference in cellularity. When, to eliminate the effect of the latter, receptor concentration in each tumour deposit was corrected using the appropriate cellularity index, the difference in receptor concentration between primary and node was significantly diminished, but not quite eliminated. In one patient, progestogen receptor concentrations were also studied and found to be higher in the nodes than in the primary tumour. If the actual quantity of receptor is to be used for predictive/prognostic purposes, then either a different cut-off point should be used for invaded nodes from that used for assessment on the primary tumour, or receptor concentrations should be corrected for differences in cellularity. Reprints: No reprints are supplied by this Department.     

Sex hormone-induced mammary carcinogenesis in the female Noble rats: Expression of Bcl-2 and Bax in hormonal mammary carcinogenesis

We have established a Noble rat model to explore the mechanisms of hormonal mammary carcinogenesis, in which the role of androgen in promoting mammary carcinogenesis was highlighted. We have also established that stromal-epithelial interactions may be responsible for the promotional effects of testosterone in mammary carcinogenesis. Based on these understandings, in the present study we examined the expression of Bcl-2 and Bax in pre-malignant mammary glands from rats treated with different protocols of sex hormones for 7 weeks as well as sex hormone induced mammary tumours. We observed that Bcl-2 was strongly expressed in most of mammary tumour cells, whereas weak or negative in adjacent normal or hyperplastic ductal structures. On the contrary, Bax immunoreactivity was weak in mammary tumour cells while strongly expressed in adjacent normal or hyperplastic ductal structures. More importantly, the results from comparative study of pre-malignant glands further showed that when animals were treated with 17-oestradiol, the mammary epithelial cells expressed high levels of Bcl-2. The results from rats treated with testosterone, either alone or in combination with oestrogen, give rise to high levels of Bax expression in pre-malignant mammary glands. These observations indicate that in pre-malignant mammary glands, treatment with testosterone, either alone or in combination with 17-oestradiol, may induce high apoptotic activities. However, in fully developed mammary tumours, the apoptotic activities apparently decrease in tumour cells. TUNEL assay provides further data to support this conclusion. Our study, thus, suggests that androgens may play a promoting role in mammary carcinogenesis by upregulation of Bax expression and induction of high apoptotic activities in pre-malignant stage, which would provide a selective pressure favouring the expansion of the initiated cells.