Validation of a new prognostic model to easily predict outcome in renal cell carcinoma: the GRANT score applied to the ASSURE trial population.

Background: Prognostic scores have been developed to estimate the risk of recurrence and the probability of survival after nephrectomy for renal cell carcinoma (RCC). The use of these tools, despite being helpful to plan a customized schedule of follow-up, to the patient's tailored counselling and to select individuals who could potentially benefit from adjuvant treatment, currently is not routine, due to their relative complexity and to the lack of histological data (i.e. necrosis). Patients and methods: We developed a simple score called GRade, Age, Nodes and Tumor (GRANT) based on four easily obtained parameters: Fuhrman grade, age, pathological nodal status and pathological tumor size. Patients with 0 or 1 factor are classified as favorable risk, whereas patients with two or more risk factors as unfavorable risk. The large population of RCC patients from the ASSURE adjuvant trial was used as independent dataset for this external validation, to investigate the prognostic value of the new score in terms of disease-free survival and overall survival and to evaluate its possible application as predictive tool. Statistical analyses were carried out by the Department of Biostatistics & Computational Biology, Dana-Farber Cancer Institute (Boston, USA) for the ASSURE trial patients' population. Results: The performance of the new model is similar to that of the already validated score systems, but its strength, compared with the others already available, is the ease and clarity of its calculation, with great speed of use during the clinical practice. Limitations are the use of the Fuhrman nuclear grade, not valid for rare histologies, and the TNM classification modifications over time. Conclusion: The GRANT score demonstrated its potential usefulness for clinical practice. ClinicalTrials.gov Identifier for the ASSURE trial: NCT00326898.

Primary radiotherapy vs conservative management for localized prostate cancer--a population-based study.

BACKGROUND: Radiotherapy is the most common curative cancer therapy used for elderly patients with localized prostate cancer. However, the effectiveness of this approach has not been established. The purpose of this study is to evaluate the long-term outcomes of primary radiotherapy compared with conservative management in order to facilitate treatment decisions. METHOD: This population-based study consisted of 57,749 patients with T1-T2 prostate cancers diagnosed during 1992-2007. We utilized an instrumental variable (IV) analytical approach with competing risk models to evaluate the outcomes of primary radiotherapy vs conservative management. The IV was comprised of combined health service areas with high- and low-use areas corresponding to the top and bottom tertile in radiotherapy usage rates. RESULTS: In patients with low-/intermediate-risk prostate cancer, 10-year prostate cancer-specific and overall survival was similar in high- and low-radiotherapy use areas (96.1 vs 95.4% and 56.6 vs 56.3%, respectively). In patients with high-risk disease, however, areas with high-radiotherapy use had a higher 10-year cancer-specific survival (90.2 vs 88.1%, difference 2.1%; 95% CI 0.3-4.0%) and 10-year overall survival (53.3 vs 50.2%, difference 3.1%; 95% CI 1.3-6.3%). Results were similar irrespective of the type of radiotherapy used. To assess the robustness of our choice of IV, we repeated the IV analytical approach using different IVs (using the median utilization rate as the cutoff) and found the results to be similar. CONCLUSIONS: Among men >65 years of age, the benefit of primary radiotherapy for localized disease is largely confined to patients with high-risk prostate cancer (Gleason scores 7-10).

Contribution of serine, folate and glycine metabolism to the ATP, NADPH and purine requirements of cancer cells.

Recent observations on cancer cell metabolism indicate increased serine synthesis from glucose as a marker of poor prognosis. We have predicted that a fraction of the synthesized serine is routed to a pathway for ATP production. The pathway is composed by reactions from serine synthesis, one-carbon (folate) metabolism and the glycine cleavage system (SOG pathway). Here we show that the SOG pathway is upregulated at the level of gene expression in a subset of human tumors and that its level of expression correlates with gene signatures of cell proliferation and Myc target activation. We have also estimated the SOG pathway metabolic flux in the NCI60 tumor-derived cell lines, using previously reported exchange fluxes and a personalized model of cell metabolism. We find that the estimated rates of reactions in the SOG pathway are highly correlated with the proliferation rates of these cell lines. We also observe that the SOG pathway contributes significantly to the energy requirements of biosynthesis, to the NADPH requirement for fatty acid synthesis and to the synthesis of purines. Finally, when the PC-3 prostate cancer cell line is treated with the antifolate methotrexate, we observe a decrease in the ATP levels, AMP kinase activation and a decrease in ribonucleotides and fatty acids synthesized from [1,2-(13)C2]-D-glucose as the single tracer. Taken together our results indicate that the SOG pathway activity increases with the rate of cell proliferation and it contributes to the biosynthetic requirements of purines, ATP and NADPH of cancer cells.

Enzalutamide for the treatment of castration-resistant prostate cancer.

Castration-resistant prostate cancer (CRPC) remains a major clinical challenge, given the mechanistic heterogeneity due to a complex signal transduction network. Enzalutamide (MDV-3100), recently approved by the U.S. Food and Drug Administration (FDA) at a dose of 160 mg/day for the treatment of CRPC, blocks androgen signaling by directly binding to the androgen receptor (AR) and inhibiting nuclear translocation and coactivator recruitment of the ligand-receptor complex. In preclinical studies, enzalutamide has been shown to block the binding of AR to DNA, resulting in apoptosis and retardation of tumor growth. Clinically, a phase I/II study (N = 140) revealed that enzalutamide had an optimal safety profile and significant antitumor activity in patients with CRPC regardless of prior chemotherapy. In the AFFIRM phase III trial (N = 1,199), oral enzalutamide significantly improved survival in men with metastatic CRPC after chemotherapy. Currently, a phase III trial (PREVAIL) is under way to determine the effectiveness of enzalutamide in patients who have not received prior docetaxel chemotherapy.

Phase II trial of weekly patupilone in patients with castration-resistant prostate cancer.

BACKGROUND: Drug resistance mechanisms can reduce response rate and duration in men with castration-resistant prostate cancer (CRPC) receiving docetaxel-based therapy. Patupilone (epothilone B), a microtubule-targeting agent, may be unaffected by some resistance mechanisms. Therefore, a phase II study assessed the patupilone safety and activity in CRPC patients with and without previous chemotherapy. METHODS: CRPC patients received patupilone 2.5 mg/m(2) weekly for 3 weeks of a 4-week cycle. Patients were required to have measurable disease or prostate-specific antigen (PSA) progression (levels>20 ng/ml). RESULTS: All 45 enrolled patients (median age, 69 years) were safety and response assessable. Sixty-four percent had previous chemotherapy (55% had previous taxane therapy). Patients received a median of three patupilone cycles. Patupilone was generally well tolerated. Ten (22%) patients experienced grade 3 diarrhea, six (13%) grade 3 fatigue, and one (2%) grade 3 neuropathy with no neutropenia or thrombocytopenia incidence. Six (13%) patients had >or= 50% decline in PSA (three had previous taxane therapy). No patient with measurable disease had a response. Median overall survival was 13.4 months. CONCLUSIONS: The safety profile of weekly patupilone in CRPC patients compares favorably with that of other microtubule inhibitors. At the dose and schedule tested, patupilone demonstrated minimal activity in CRPC.

A phase I trial of pox PSA vaccines (PROSTVAC-VF) with B7-1, ICAM-1, and LFA-3 co-stimulatory molecules (TRICOM) in patients with prostate cancer.

PURPOSE: Based on previous studies that demonstrated the safety profile and preliminary clinical activity of prostate specific antigen (PSA) targeted therapeutic vaccines, as well as recent laboratory data supporting the value of the addition of co-stimulatory molecules B7-1, ICAM-1, and LFA-3 (designated TRICOM) to these vaccines, we conducted a Phase I study to evaluate the safety and immunogenicity of a novel vaccinia and fowlpox vaccine incorporating the PSA gene sequence and TRICOM. METHODS: In this study, ten patients with androgen independent prostate cancer with or without metastatic disease were enrolled. Patients were treated with 2 x l0(8) pfu of a recombinant vaccinia virus vaccine (PROSTVAC-V) followed by 1 x 10(9) pfu of the booster recombinant fowlpox virus (PROSTVAC-F) both with gene sequences for PSA and TRICOM. The mean age of patients enrolled in the study was 70 (range 63 to 79). The mean PSA at baseline was 434 (range 9-1424). RESULTS: There were no deaths, and no Grade 3 or 4 adverse events. The most commonly reported adverse events, regardless of causality, were injection site reactions and fatigue. One serious adverse event (SAE) occurred that was unrelated to vaccine; this patient developed progressive disease with a new sphenoid metastasis. PSA was measured at week 4 and week 8. Four patients had stable disease (with less than 25% increase in PSA) through the week 8 study period. Anti-PSA antibodies were not induced with therapy: however, anti-vaccinia titers increased in all patients. CONCLUSION: This study demonstrated that vaccination with PROSTVAC-V and PROSTVAC-F combined with TRICOM is well-tolerated and generated an immune response to vaccinia. Therefore, PROSTVAC-VF/TRICOM represents a feasible therapeutic approach for further phase II and III study in patients with prostate cancer.

Furanosesquiterpenoids of Commiphora myrrha.

An investigation on the gum exudates of Commiphora myrrha has led to the isolation of six sesquiterpenoids. On the basis of spectroscopic data interpretation, they were determined as two new furanosesquiterpenoids, rel-1S,2S-epoxy-4R-furanogermacr-10(15)-en-6-one (1) and rel-2R-methyl-5S-acetoxy-4R-furanogermacr-1(10)Z-en-6-one (2), and four known furanosesquiterpenoids, rel-3R-methoxy-4S-furanogermacra-1E,10(15)-dien-6-one (3), rel-2R-methoxy-4R-furanogermacr-1(10)E-en-6-one (4), furanogermacra-1(10)Z,4Z-dien-6-one, and curzerenone [6,7-dihydro-5beta-isopropenyl-3,6beta-dimethyl-6-vinylbenzofuran-4(5H)-one]. This is the first report of the relative stereochemistry for the known compounds 3 and 4. Compound 1 exhibited weak cytotoxic activity against a MCF-7 breast tumor cell line in a clonogenic assay, while the other five compounds were inactive in this assay.

Mitoxantrone in patients with prostate specific antigen progression after local therapy for prostate carcinoma.

BACKGROUND: Molecular mechanisms of chemotherapy resistance are present in prostate carcinoma, some of which increase after androgen ablation (AA) therapy. Therefore, the authors hypothesized that chemotherapy in patients with prostate specific antigen (PSA) progression after local therapy, before androgen ablation therapy, will have greater antitumor activity. METHODS: Twenty-three hormone-naive patients with PSA progression after prostatectomy or radiation therapy were registered in this study. Twenty-two were treated with 10 mg/m(2) of mitoxantrone initially, followed by 12 mg/m(2) every 3 weeks for a maximum of 8 cycles. Prostatectomy specimens were assessed, when possible, for topoisomerase II alpha, multidrug resistance protein MRP, and bcl-2 by immunohistochemistry. RESULTS: Twenty-two patients received a total of 131 cycles of therapy. Three patients had transient Grade 3 or 4 neutropenia without fever. During treatment, 10 of 22 patients showed a decrease in PSA, without an associated decrease in testosterone. In this group of 10 patients, the mean PSA decrease was 29% at 3 months and 43% at 6 months. Overall, 4 of 22 patients had a decrease in PSA of greater than or equal to 50%. The PSA decreased in three of seven patients whose cancer overexpressed MRP and in three of seven patients who overexpressed bcl-2. No patient with overexpression of topoisomerase II alpha (n = 4) had a decrease in PSA during the study. CONCLUSIONS: To the authors' knowledge, this is the first reported study of mitoxantrone in patients with hormone-naive prostate carcinoma and PSA progression after local therapy; mitoxantrone was safe and biochemically active, similar to prior studies in hormone refractory prostate carcinoma, suggesting that critical molecular mechanisms of chemotherapy resistance are present independent of AA. Further studies are warranted to determine whether pharmacogenomic assessment of topoisomerase II, MRP, or bcl-2 may predict for response to mitoxantrone.

Targeting apoptosis in prostate cancer.

The understanding of apoptotic pathways provides new insights into cancer therapy. Therapies that modulate these pathways may induce apoptosis or sensitize tumor cells to other agents. Because many of the components of these pathways are altered in tumor cells compared with normal cells, therapies that target these abnormal apoptotic proteins may be more selective than traditional cytotoxic agents. Difficulties include the translation of the knowledge of these pathways into clinical trials and monitoring the predicted biologic effects in patients. The continued study of new targets, agents capable of modulating these targets, and markers of biologic effect in patients should improve clinical results.

Metastatic renal cell carcinoma presenting as an oral tumor.

Metastatic cancer presenting as an oral lesion is exceedingly uncommon. To the best of our knowledge this is the first reported instance of renal cell carcinoma presenting initially as an oral lesion.

Bioactive constituents from gum guggul (Commiphora wightii).

Bioactivity-directed fractionation and purification afforded cytotoxic components of Commiphora wightii. The exudates of C. wightii were extracted with EtOAc and the extract was subjected to repeated column chromatography. A fraction showing cytotoxic activity was characterized as a mixture of two ferulates with an unusual skeleton by spectral and chemical methods, including by NMR, GC-MS and chemical derivatization. This fraction also showed moderate scavenging effect against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals.

State-of-the-art prostate cancer treatment and research. A report from the Cancer Institute of New Jersey.

Prostate cancer is a devastating disease that will be diagnosed in approximately 200,000 men in 2001. New methods for screening, prevention, and treatment are being developed. In addition, novel agents for the treatment of resistant prostate cancer are being developed in clinical trials. This review summarizes the recent efforts in diet, screening, novel systemic therapies, and alternative medicine for prostate cancer.

Modulation of bcl-2 and cytotoxicity by licochalcone-A, a novel estrogenic flavonoid.

Herbal therapies are commonly used by patients with cancer, despite little understanding about their clinical and biological activity. We recently demonstrated that the herbal combination PC-SPES, which contains licorice root, had potent estrogenic activity in vitro, in animals, and in patients with prostate cancer. Licochalcone-A (LA) is one flavonoid extracted from licorice root with antiparasitic and anti-tumor activity, but the effect on the human estrogen receptor and mechanism of anti-tumor activity is unknown. Recent studies demonstrated that the mechanism of cytotoxic effect by some estrogens may involve modulation of the anti-apoptotic protein bcl-2. In the present study, we determined if LA had estrogenic activity, anti-tumor activity, and modulated the apoptotic protein bcl-2 in human cell lines derived from acute leukemia, breast cancer, and prostate cancer. A yeast growth-based assay under the control of the human estrogen receptor (hER) demonstrated that LA was a phytoestrogen. A cell viability assay demonstrated that LA had anti-tumor activity in all cell lines tested and enhanced the effect of paclitaxel and vinblastine chemotherapy. LA induced apoptosis in MCF-7 and HL-60 cell lines, as demonstrated by cleavage of PARP, the substrate of ICE-like proteases. Immunoblot analysis demonstrated that LA decreased the anti-apoptotic protein bcl-2 and altered the bcl-2/bax ratio in favor of apoptosis. In contrast, the parent compound chalcone or estradiol did not decrease bc1-2 expression. Therefore, these data demonstrate that LA is a phytoestrogen with anti-tumor activity and is capable of modulating bcl-2 protein expression. The modulation of bcl-2 may be dependent on specific structural differences between LA and the parent compound chalcone and independent of LA estrogenicity.

Extracellular catalytic subunit activity of the cAMP-dependent protein kinase in prostate cancer.

The role of cAMP in cell growth and differentiation, gene expression, and neuronal function is mediated by the cAMP-dependent protein kinase (PKA). Differential expression of type I and type II PKA has been correlated with neoplastic transformation and differentiation, respectively. PKA is primarily an intracellular enzyme. However, it has been demonstrated that PKA may be associated with the plasma membrane and is exposed to the extracellular environment. Here we report the first evidence for the presence of a free extracellular kinase activity of PKA in the growth media of cultured prostate and other cancer cells, as well as in plasma samples from prostate cancer patients. This PKA activity is specific due to its phosphorylation of the PKA-specific substrate kemptide and its inhibition by the potent and specific PKA inhibitor PKI, but not by other protein kinase-inhibitory peptides. Intriguingly, this exoprotein kinase activity is cAMP independent, suggesting that only the catalytic subunit is secreted, and therefore the kinase activity is not modulated by the regulatory subunit of PKA. Western blot analysis of the culture supernatant from prostate cancer cells indicates the presence of the catalytic subunit. This increase in extracellular PKA catalytic subunit activity in prostate cancer may have profound effects on the tumorigenesis of prostate cancer and may serve as a novel marker and therapeutic target for the disease.

Approaches to the treatment of patients with hormone-sensitive prostate cancer.

Androgen ablation therapy provides effective palliation for patients with advanced cancer of the prostate for only a short duration because the tumor eventually develops resistance. Among the many potential molecular mechanisms involved in the development of tumor resistance to both androgen ablation therapy and chemotherapy, mutations in the p53 tumor suppressor gene, overexpression of the antiapoptotic protein bcl-2, and overexpression of the multidrug resistance protein probably play a role. Because hormone-resistant tumors demonstrate greater expression of bcl-2 and because transfection of the bcl-2 gene into hormone-sensitive tumor cells confers resistance to both hormone therapy and chemotherapy, efforts to abrogate bcl-2 in prostate tumors represent one approach to improve clinical results. Of several agents recently shown to reduce prostate-specific antigen levels in phase II studies, 13-cis-retinoic acid and interferon-alpha can reduce the expression of bcl-2 and overcome bcl-2-mediated resistance to paclitaxel in resistant cell lines. For these reasons, our current studies test the hypothesis that reducing the expression of bcl-2 with 13-cis-retinoic acid and interferon-alpha in combination with taxanes will improve clinical results. Additionally, other studies test the hypothesis that treatment early, before the development of resistance mechanisms, in hormone-sensitive disease will improve results. Studies with docetaxel (Taxotere; Rhône-Poulenc Rorer, Collegeville, PA) and with estramustine combination therapy are also ongoing.

Phase I clinical and pharmacologic study of 13-cis-retinoic acid, interferon alfa, and paclitaxel in patients with prostate cancer and other advanced malignancies.

PURPOSE: Recent studies demonstrate that retinoids decrease expression of the anti-apoptotic protein bcl-2, enhance the effect of chemotherapy, and act synergistically with interferon alfa (IFNalpha) to inhibit tumor cell growth in vitro. A phase I trial of 13-cis-retinoic acid (CRA), IFNalpha, and paclitaxel (TAX) was conducted to determine the toxicity and recommended phase II dose of this combination. Pharmacodynamic studies were performed to determine whether CRA and IFNalpha could modulate bcl-2 expression in vitro and in patients. PATIENTS AND METHODS: Twenty-two patients with prostate cancer or other advanced malignancies were treated with CRA/IFNalpha and escalating doses of TAX. The effect of CRA/IFNalpha on TAX pharmacokinetics was analyzed in both patients and human liver microsomes. The effect of CRA/IFNalpha on bcl-2 expression was assessed in vitro and in peripheral-blood mononuclear cells (PBMCs) by immunoblotting. RESULTS: CRA 1 mg/kg on days 1 to 4, IFNalpha 6 MU/m(2) subcutaneously on days 1 to 4, and TAX 175 mg/m(2) on day 3 was well tolerated. Pharmacokinetic studies demonstrated that CRA/IFNalpha caused a 33% decrease in TAX clearance and a 23% decrease in the area under the concentration-time curve values of the TAX metabolite 6-alfa-hydroxytaxol (6-HT). CRA alone reduced conversion of TAX to 6-HT by 41% in human liver microsomes. CRA/IFNalpha decreased bcl-2 expression in vitro and in PBMCs. CONCLUSION: CRA/IFNalpha and TAX is a well-tolerated regimen. CRA/IFNalpha increases TAX area under the concentration-time curve through an inhibitory effect of CRA on the metabolism of TAX to 6-HT. CRA/IFNalpha can modulate bcl-2 expression in vitro and demonstrates similar biologic activity in patients. Further studies will determine the activity of CRA/IFNalpha/TAX and validate the assessment of bcl-2 in PBMCs as a marker of tumor response.

Neurologic protection by amifostine.

Amifostine (Ethyol; Alza Pharmaceuticals, Palo Alto, CA/US Bioscience, West Conshohocken, PA) is a thiophosphate cytoprotectant agent with the potential to abrogate many chemotherapy-induced toxicities. In preclinical studies, amifostine protected against the cytotoxic effects of alkylating agents, platinum analogs, and radiation therapy in normal tissues, but preserved antineoplastic activity of these therapeutic modalities in tumor tissue. Most normal tissues were protected, including bone marrow, kidney, lung, and peripheral nerves. Recently, the protective effects of amifostine were confirmed by clinical studies, including a randomized trial demonstrating protection from cisplatin-induced myelosuppression, nephrotoxicity, and neurotoxicity. Many common chemotherapeutic agents, such as cisplatin, paclitaxel, and vinca alkaloids, cause dose-limiting neurotoxicity. Therefore, a neurologic protectant may help to reduce toxicity to patients, improve the tolerability of combination therapy with multiple neurotoxic agents, or allow investigators to intensify chemotherapy dose. This report reviews the potential role of amifostine as a neuroprotectant. Future clinical trials may expand the use of amifostine to abrogate neurotoxicity from multiple agents and combinations and compare amifostine with other neuroprotective agents.

Overcoming bcl-2- and p53-mediated resistance in prostate cancer.

Most prostate cancers eventually develop resistance to hormonal therapy and chemotherapies. Many mechanisms for resistance to chemotherapy have been identified. Mutations or inactivation of the p53 suppressor gene and overexpression of bcl-2 are among such mechanisms. Mutations in the p53 gene can lead to resistance to certain chemotherapy agents, and such mutations are seen more often in metastatic than in primary prostate cancers. Thus, agents that are active in the setting of mutated p53 may have some advantage in prostate cancer. Overexpression of bcl-2 occurs frequently in prostate cancer and is associated with both hormonal therapy and chemotherapy resistance. In experimental systems, bcl-2 overexpression occurs after androgen deprivation and transfection of bcl-2 into sensitive cell lines makes them resistant to chemotherapy and hormonal therapies. Bcl-2 can be inactivated by phosphorylation as occurs with taxanes. The retinoids, as a class, can inhibit the growth of resistant cell lines that overexpress bcl-2, and the combination of interferon (IFN) and cis-retinoic acid (CRA) demonstrated increased antitumor activity. In our cell line model the combination of IFN and CRA greatly enhanced the cytotoxicity of paclitaxel (Taxol; Bristol-Myers Squibb Company, Princeton, NJ). Based on these observations, we conducted a phase I/II trial of CRA and IFN-alpha in patients with biochemical recurrence of prostate cancer. Twenty-six percent achieved a decrease of prostate-specific antigen (PSA), which was correlated to elevated serum transforming growth factor-beta. We then conducted a phase I trial of 13-CRA, IFN-alpha, and escalating doses of paclitaxel. Eighteen patients were treated with 1 mg/kg CRA and 1x10(6) unit IFN on days 1 to 4 and paclitaxel at doses from 100 to 175 mg/m2. Eleven patients received the 175 mg/m2 paclitaxel dose. Two patients in the phase I study achieved partial responses (one cervix and one prostate cancer). We subsequently initiated a phase II study of 13-CRA, IFN-alpha, and paclitaxel in hormone refractory prostate cancer. For entry patients must show progressive disease after androgen ablation. To test the mechanism of action, we are assaying peripheral blood monocytes and, when possible, tumor tissue for bcl-2 expression. As our understanding of the mechanisms of tumor resistance to chemotherapy improves, we will be able to design better approaches in treatment targeted to overcome the mechanisms of resistance.

Clinical and biologic activity of an estrogenic herbal combination (PC-SPES) in prostate cancer.

BACKGROUND: Herbal mixtures are popular alternatives to demonstrated therapies. PC-SPES, a commercially available combination of eight herbs, is used as a nonestrogenic treatment for cancer of the prostate. Since other herbal medicines have estrogenic effects in vitro, we tested the estrogenic activity of PC-SPES in yeast and mice and in men with prostate cancer. METHODS: We measured the estrogenic activity of PC-SPES with transcriptional-activation assays in yeast and a biologic assay in mice. We assessed the clinical activity of PC-SPES in eight patients with hormone-sensitive prostate cancer by measuring serum prostate-specific antigen and testosterone concentrations during and after treatment. RESULTS: In complementary yeast assays, a 1:200 dilution of an ethanol extract of PC-SPES had estrogenic activity similar to that of 1 nM estradiol, and in ovariectomized CD-1 mice, the herbal mixture increased uterine weights substantially. In six of six men with prostate cancer, PC-SPES decreased serum testosterone concentrations (P<0.05), and in eight of eight patients it decreased serum concentrations of prostate-specific antigen. All eight patients had breast tenderness and loss of libido, and one had venous thrombosis. High-performance liquid chromatography, gas chromatography, and mass spectrometry showed that PC-SPES contains estrogenic organic compounds that are distinct from diethylstilbestrol, estrone, and estradiol. CONCLUSIONS: PC-SPES has potent estrogenic activity. The use of this unregulated mixture of herbs may confound the results of standard or experimental therapies and may produce clinically significant adverse effects.