Evaluation of cathepsin D as a prognostic factor in breast cancer

The biologic rationale for the importance of cathepsin D in breast cancer is a provocative one. Cathepsin D is both an estrogen inducible and a constitutively produced protease, which may also act directly as a peptide growth factor. Thus it may play a role in tumor invasiveness, and also in driving cell proliferation. Reported clinical studies are conflicting, with some studies showing cathepsin D levels to correlate with clinical outcome, and other studies finding prognostic significance only in selected subsets of patients, if any. Thus cathepsin D is a potentially important prognostic marker whose clinical application awaits further definition.

Neural Network Analysis of DNA flow cytometry histograms

A pattern recognition system based on Neural Network Analysis, a form of artificial intelligence, was used to search DNA flow cytometry histograms for features that correlated with breast cancer patients' risk of relapse. DNA flow cytometry histograms and clinical follow-up information from 796 breast cancer patients were used to train a Neural Network to predict the clinical outcome of patients in a separate independent set of 794 patients. Median follow-up in this patient data base was short, 23 months. Neural Network Analysis resulted in a model that evaluated DNA flow cytometry histograms differently than conventional analysis, which categorizes the histograms by ploidy and S-phase fraction. Neural Network Analysis appeared to identify low risk and high risk subsets of patients as accurately as conventional analysis. Neural Network Analysis placed heavy emphasis on the region to the right of the diploid G2/M peak, where a subpopulation of nuclei with high DNA content is seen even in many histograms scored as diploid by conventional techniques. The number of nuclei in this region was found to be a powerful predictor of patient outcome, and multivariate analysis showed that the number of nuclei in this region and the S-phase fraction both were independently predictive of relapse. This pilot study suggests that conventional analysis (based on a mechanistic interpretation of regions in flow cytometry histograms) might be used in conjunction with and improved by pattern recognition systems or insights derived from them.

Prognosis and treatment decisions in patients with breast cancer without axillary node involvement

BACKGROUND

Every month, treatment decisions must be made for more than 6000 patients with breast cancer without axillary node involvement in the United States. Approximately 70% of these patients will survive more than 10 years after surgery and/or radiation treatment without additional systemic adjuvant therapy. If we had good methods to identify patients who are destined to have a recurrence of their disease, only those patients should receive adjuvant therapy.

METHODS

The authors reviewed the literature supporting the use of currently available prognostic factors for patients with node-negative breast cancer, and formulated a framework on which prognostic factor information can be based to help make these treatment decisions.

RESULTS

The steps involved in making treatment decisions are: use prognostic factors to determine the recurrence probability; calculate the expected treatment benefit; and weigh the expected benefits against the potential risks.

CONCLUSIONS

Prognostic factors can be used to help make treatment decisions for patients with breast cancer without axillary node involvement. However, the final treatment decision must take into account all aspects of the patient and her disease, and the physician must help the patient evaluate her prognostic factors, arrive at an understanding of her particular risk of recurrence, and weigh the potential benefits and risks of adjuvant therapy.

A practical application of neural network analysis for predicting outcome of individual breast cancer patients

It has been previously shown that Neural Networks can be trained to recognize individual breast cancer patients at high and low risk for recurrent disease and death. This paper expands on the initial investigation and shows that by coding time as one of the prognostic variables, a Neural Network can use censored survival data to predict patient outcome over time. In this demonstration a Neural Network was trained, tested, and validated using censored survival data from a group of 1373 patients with node-positive breast cancer. The Neural Network method predicted patient outcome as accurately as Cox Regression modeling. The final Neural Network model can be presented with a patient's prognostic information and make a series of predictions about probability of relapse at different times of follow-up, allowing one to draw survival probability curves for individual patients.

Prognosis and treatment decisions in patients with breast cancer without axillary node involvement

BACKGROUND

Every month, treatment decisions must be made for more than 6000 patients with breast cancer without axillary node involvement in the United States. Approximately 70% of these patients will survive more than 10 years after surgery and/or radiation treatment without additional systemic adjuvant therapy. If we had good methods to identify patients who are destined to have a recurrence of their disease, only those patients should receive adjuvant therapy.

METHODS

The authors reviewed the literature supporting the use of currently available prognostic factors for patients with node-negative breast cancer, and formulated a framework on which prognostic factor information can be based to help make these treatment decisions.

RESULTS

The steps involved in making treatment decisions are: use prognostic factors to determine the recurrence probability; calculate the expected treatment benefit; and weigh the expected benefits against the potential risks.

CONCLUSIONS

Prognostic factors can be used to help make treatment decisions for patients with breast cancer without axillary node involvement. However, the final treatment decision must take into account all aspects of the patient and her disease, and the physician must help the patient evaluate her prognostic factors, arrive at an understanding of her particular risk of recurrence, and weigh the potential benefits and risks of adjuvant therapy.

Prognostic significance of progesterone receptor levels in estrogen receptor-positive patients with metastatic breast cancer treated with tamoxifen: results of a prospective Southwest Oncology Group study

PURPOSE

Southwest Oncology Group (SWOG) protocol 8228 is a prospective trial designed to investigate the prognostic significance of progesterone receptor (PgR) levels in estrogen receptor (ER)-positive breast cancer patients who were treated with tamoxifen. This study was undertaken because the value of PgR measurements in advanced breast cancer had been assessed previously only in studies that were small, retrospective, or included heterogeneously treated patients.

METHODS

Receptor assays were performed only in the laboratories that met strict quality control guidelines. Of the 398 patients entered, 342 patients were eligible and assessable for the study end points of objective clinical response, time to treatment failure, and overall survival.

RESULTS

Multivariate analysis shows that elevated PgR levels significantly and independently correlated with increased probability of response to tamoxifen, longer time to treatment failure, and longer overall survival. Overall response rate (defined as complete response [CR], partial response [PR], or stable disease [SD] for greater than 6 months) in this trial was 54%. Response rates to tamoxifen were 43%, 53%, and 61% in subsets of patients with less than 10, 10 to 99, and more than 100 fmol/mg PgR, respectively. Exploratory subset analysis using PgR and other prognostic variables identified ER-positive patient subsets with response rates to tamoxifen ranging from 24% (premenopausal patients) to 86% (postmenopausal patients with ER greater than 38 and PgR greater than 329 fmol/mg). No groups of ER-positive patients were identified who had such a low response rate as to absolutely preclude considering the use of tamoxifen. Multivariate analysis showed the independent, statistically significant predictors were: for response to tamoxifen, menopausal status, PgR, and ER; for time to treatment failure, menopausal status, disease-free interval (DFI), PgR, and ER; and for overall survival DFI, PgR, ER, site of disease, and history of adjuvant therapy.

CONCLUSION

We conclude that knowledge of PgR levels together with other clinical information can improve the pretreatment assessment of ER-positive breast cancer patients with metastatic disease.

A demonstration that breast cancer recurrence can be predicted by neural network analysis

Neural Network Analysis, a form of artificial intelligence, was successfully used to predict the clinical outcome of node-positive breast cancer patients. A Neural Network was trained to predict clinical outcome using prognostic information from 1008 patients. During training, the network received as input information tumor hormone receptor status, DNA index and S-phase determination by flow cytometry, tumor size, number of axillary lymph nodes involved with tumor, and age of the patient, as well as length of clinical followup, relapse status, and time of relapse. The ability of the trained Network to determine relapse probability was then validated in a separate set of 960 patients. The Neural Network was as powerful as Cox Regression Modeling in identifying breast cancer patients at high and low risk for relapse.

A phase I clinical and pharmacokinetic trial of hepsulfam

Hepsulfam (1,7-heptanediol-bis-sulfamate) is one of a series of bis-sulfamate acid esters that was synthesized in an attempt to improve the antitumor efficacy of busulfan. Hepsulfam has shown broad antineoplastic activity in preclinical studies. This Phase I trial evaluated hepsulfam given as a single i.v. dose every 21-35 days. Twenty-nine patients with refractory solid tumors participated in this study. Twenty-six of these patients had had either prior chemotherapy or radiation therapy. Fifty-two courses of treatment were given at doses ranging from 30 to 360 mg/m2/day. The dose limiting toxicity was prolonged thrombocytopenia and granulocytopenia. This toxicity was cumulative with Grade 3 or 4 thrombocytopenia occurring in 3 of 15, 4 of 9, and 2 of 2 patients in the first, second, and third courses of greater than or equal to 210 mg/m2, respectively. This toxicity was noted in patients with less than or equal to 1 prior chemotherapeutic regimen, as well as in patients with greater than 1 prior chemotherapeutic regimens. Nonhematological toxicities included Grade 1 or 2 nausea and vomiting and fatigue. There was no evidence of pulmonary toxicity. Plasma levels of hepsulfam were quantified by gas chromatography in 12 patients. The plasma and blood half-lives were 15.9 +/- 4.6 and 90 +/- 13 h, respectively. No objective tumor responses were seen. We conclude that the maximally tolerated dose when hepsulfam is given as a single dose every 35 days is 210 mg/m2, but that there is significant risk of cumulative hematological toxicity at this level.

Endocrine status of premenopausal node-positive breast cancer patients following adjuvant chemotherapy and long-term tamoxifen

The endocrine status of 49 premenopausal women taking tamoxifen after completion of adjuvant chemotherapy for breast cancer was determined by radioimmunoassay from serial blood samples. Of these 49 women, 7 had regular menses, 14 had irregular menses, 23 were amenorrheic, and 5 had undergone hysterectomies. A group of 12 premenopausal women who had no history of breast cancer and were not taking tamoxifen served as a control group. Evidence of ovarian function (estradiol levels of greater than 100 pg/ml) was seen in 7 of 7, 9 of 14, 2 of 23, and 1 of 5 women with a clinical history of regular menses, irregular menses, amenorrhea, and hysterectomy, respectively. Supraphysiological levels of estradiol (greater than 350 pg/ml) were noted in 13 of 19 women with endocrine evidence of ovarian function. Supraphysiological progesterone levels (greater than 20 ng/ml) were also seen in 5 of 7 of the regularly menstruating women taking tamoxifen. Supraphysiological levels of estradiol were associated with elevated follicle-stimulating hormone levels, but there was no mean change in the luteinizing hormone levels. Minimum and maximum serum follicle-stimulating hormone levels were 1.9 and 9.0 mIU/ml in the 12 normal women and 5.2 and 24.3 mIU in the 13 women with supraphysiological estradiol levels. Our findings demonstrate that the majority of women who continue to menstruate while taking continuous tamoxifen following cytotoxic chemotherapy have supraphysiologic estradiol levels. This is a potential mechanism for failure of tamoxifen therapy in these premenopausal women.

Active immunization to luteinizing hormone releasing hormone to inhibit the induction of mammary tumors in the rat

Immunization of female rats with a bovine serum albumin-luteinizing hormone releasing hormone conjugate results in suppression of dimethylbenzanthracene mammary tumor incidence. Tumor incidence was 1.3, and 1.29 tumors per rat in bovine serum albumin alone (n = 10) and unimmunized (n = 18) control groups, but no tumors were found in the bovine serum albumin-luteinizing hormone releasing hormone conjugate immunized animals (n = 10). In a second experiment immunization with bovine serum albumin-luteinizing hormone releasing hormone conjugates reduced tumor incidence to 0.3 tumors per rat (n = 10) from the 1.2 tumors per animal seen in the control animals (n = 10) immunized with bovine serum albumin alone. Bovine serum albumin-luteinizing hormone immunization caused the production of anti-LHRH antibodies, an interruption of estrous cycles, lowered serum estradiol and progesterone levels, and atrophy of the ovaries and uteri. Immunization BSA-hormone conjugates is a novel anti-tumor strategy.

Estrogenic effects of phenolphthalein on human breast cancer cells in vitro

There is a structural similarity between phenolphthalein and the triphenylethylenes which are known to interact with the estrogen receptor of human breast tissue. Phenolphthalein (10 microM) competed with estrogen for binding to MCF-7 human breast cancer cells in tissue culture and induced the synthesis of the progesterone receptor. The antiestrogen 4-hydroxytamoxifen blocked progesterone receptor induction both by estradiol and by phenolphthalein. Both estradiol (0.1 nM) and phenolphthalein (10 microM) stimulated cell growth as measured by DNA and protein assays. This growth stimulation was blocked by 4-hydroxytamoxifen. Phenolphthalein glucuronide, the major phenolphthalein metabolite, did not inhibit estrogen binding, induce progesterone receptor synthesis, or stimulate MCF-7 cell growth in culture. Yellow phenolphthalein, an impure phenolphthalein preparation used in nonprescription laxative preparations, had similar properties to pure phenolphthalein. Physicians should be aware of the weak estrogenic action of phenolphthalein, especially when recommending laxatives for breast cancer patients with confirmed liver and mesenteric metastases.

Internalization of alpha-bungarotoxin on neurons induced by a neurotoxin that blocks neuronal acetylcholine sensitivity

A protein neurotoxin (Bgt 3.1) present as a minor component in the venom of Bungarus multicinctus has been shown previously to block acetylcholine (ACh) sensitivity on chick ciliary ganglion (CG) neurons in cell culture. Alpha-bungarotoxin (Bgt. 2.2) binds to the neurons but does not block ACh sensitivity; the function of the Bgt. 2.2 binding site is unknown. The present studies demonstrate that Bgt 3.1 can induce the rapid internalization of Bgt 2.2 bound on the surface of CG and sympathetic neurons. The rapid internalization of bound Bgt 2.2 caused by Bgt. 3.1 can be seen with fluoresence microscopy using rhodamine-labeled Bgt 2.2 as the probe and by immunological techniques using anti-Bgt 2.2 antiserum to locate the bound 125I-Bgt 2.2. The rapid internalization is blocked by low temperature or by high concentrations of Bgt 2.2 and is not induced by Bgt 2.2 itself or by small cholinergic ligands. Bound 125I-Bgt 2.2 is released into the medium as degraded material after internalization is induced. Bgt 3.1 does not induce internalization of Bgt 2.2 bound to skeletal myotubes in culture nor does it induce the internalizaton of rhodamine-labeled nerve growth factor bound to sympathetic neurons, suggesting that its effect on neuronally bound Bgt 2.2 might be a specific one. Competition binding studies suggest that Bgt 3.1 may trigger the internalization of bound Bgt 2.2 by direct interaction with a Bgt 2.2 binding site. The effect of Bgt 3.1 on neuronal ACh sensitivity, however, does not depend on internalization of Bgt 2.2 binding sites since full inhibition of ACh sensitivity is still achieved by Bgt 3.1 under conditions where internalization is blocked. Neurons may have more than one class of Bgt 2.2 on the neurons. The internalization of Bgt 2.2 binding sites induced by Bgt 3.1 provides an unusual opportunity to study cellular mechanisms by which neurons can regulate the number and distribution of their surface components.

Inhibition of neuronal acetylcholine sensitivity by alpha-toxins from Bungarus multicinctus venom

Bungarus multicinctus venom contains several alpha-toxins in addition to the widely used alpha-bungarotoxin (Bgt 2.2). We have found that two of the alpha-toxins (Bgt 3.1 and 3.3) inhibit neuronal acetylcholine (AcCho) sensitivity when tested on ciliary ganglion neurons in cell culture. Over 90% of the AcCho sensitivity recorded in response to iontophoretic application of AcCho was blocked when the neurons were incubated with either of the toxins at 10(-7) M for 1 hr at 37 degrees C. The blockade could be partially reversed by incubating the neurons for 1-2 hr in medium lacking the toxins. The neurons also had a high-affinity binding site for Bgt 2.2, as indicated by binding studies with rhodamine-labeled Bgt 2.2. Concentrations of Bgt 2.2(10(-7) M) that should be nearly adequate to saturate the high-affinity site, however, had no detectable effect on AcCho sensitivity of the neurons. Higher concentrations of Bgt 2.2(10(-5) M) produced a partial inhibition of AcCho sensitivity, suggesting either that the neurons had two classes of binding sites for Bgt 2.2 (with the low-affinity site affecting AcCho sensitivity) or that the preparation of Bgt 2.2 contained minor components (e.g., Bgt 3.1 or 3.3) that were responsible for the blockade. The mechanisms by which Bgt 3.1 and 3.3 inhibit neuronal AcCho sensitivity remain unknown. If they bind specifically to the AcCho receptor, they will be useful agents for studying the distribution and regulation of this membrane component.