Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0376358 (prostate cancer)
 59,338 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We hypothesize that each cell in low-grade (Gleason grade 1-3) prostate cancer tissue is at risk of transformation into a cell which produces a high-grade (Gleason grade 4-5) clinical cancer after a short period of growth. As a consequence, the volume of low-grade, latent cancer tissue in the prostate glands of men at any age determines their incidence rate for high-grade, clinical cancer a few years later. Autopsy and incidence data for both white men and black men support this conclusion, with a tumor growth period of about 7 years. The transformation rate is similar for black men and for white men, about 0.024 high-grade cancers per year per cm3 of low-grade, latent cancer volume. Our hypothesis explains the infrequent occurrence of clinical cancer despite the high prevalence of latent cancer, the steep rise of clinical cancer incidence with age despite the slow rise of latent cancer prevalence with age, and the disparities in clinical cancer incidence among some populations despite their similar latent cancer prevalence. This hypothesis suggests that low-grade cancer volume is a critical determinant of clinical cancer risk.
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PMID:Low-grade, latent prostate cancer volume: predictor of clinical cancer incidence? 187 Jan 41

Inhibitory effects of the sustained delivery systems (microcapsules and microgranules) of a potent antagonist of luteinizing hormone-releasing hormone N-Ac-[3-(2-naphthyl)-D-alanine1, 4-chloro-D-phenylalanine2, 3-(3-pyridyl)-D-alanine3, D-citrulline6, D-alanine10]LH-RH (SB-75) on the growth of experimental prostate cancers were investigated. In the first experiment, three doses of a microcapsule preparation releasing 23.8, 47.6, and 71.4 micrograms of antagonist SB-75 per day were compared with microcapsules of agonist [D-Trp6]LH-RH liberating 25 micrograms/day in rats bearing Dunning R3327H transplantable prostate carcinoma. During 8 weeks of treatment, tumor growth was decreased by [D-Trp6]LH-RH and all three doses of SB-75 as compared to untreated controls. The highest dose of SB-75 (71.4 micrograms/day) caused a greater inhibition of prostate cancer growth than [D-Trp6]LH-RH as based on measurement of tumor volume and percentage change in tumor volume. Doses of 23.8 and 47.6 micrograms of SB-75 per day induced a partial and submaximal decrease, respectively, in tumor weight and volume. Tumor doubling time was the longest (50 days) with the high dose of SB-75 vs. 15 days for controls. The body weights were unchanged. The weights of testes, seminal vesicles, and ventral prostate were greatly reduced in all three groups that received SB-75, and testosterone levels were decreased to nondetectable values in the case of the two higher doses of SB-75. LH levels were also diminished. Similar results were obtained in the second experiment, in which the animals were treated for a period of 8 weeks with microgranules of SB-75. Therapy with microgranules of SB-75 significantly decreased tumor growth as measured by the final tumor volume, the percentage change from the initial tumor volume, and the reduction in tumor weight. The results indicate that antagonist SB-75, released from sustained delivery systems, can produce a state of chemical castration and effectively inhibit the growth of experimental prostate cancers. The efficacy of the antagonist SB-75 in inhibiting androgen-dependent Dunning prostatic carcinoma and the absence of side effects suggest its possible usefulness for the treatment of hormone-sensitive tumors.
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PMID:Inhibition of growth of experimental prostate cancer with sustained delivery systems (microcapsules and microgranules) of the luteinizing hormone-releasing hormone antagonist SB-75. 199 76

The effect of radiation and/or hyperthermia on a human prostatic carcinoma xenograft in athymic nude mice was investigated. A human prostate carcinoma subline (1-LN-PC-3-1A) was inoculated subcutaneously in the thigh of male athymic nude mice. When tumors reached a size of approximately 200 mm.3, they were treated with either radiation (X) or hyperthermia (H) alone, or in combination (X + H). In the combined treatment, hyperthermia was delivered immediately after radiation exposure. Comparison of the time required to reach twice the tumor volume observed at the time of treatment was used to define therapeutic impact on tumor growth. The combined treatment resulted in median tumor volume doubling time of 35.5 days, compared to 18 days and 25.5 days, respectively, for hyperthermia or radiation alone. Analysis of tumor doubling time using a proportional hazards regression indicates that under the conditions of this experiment, the effect of radiation and hyperthermia for 1-LN-PC-3-1A tumors is additive. The impact of this treatment regimen in the management of prostatic cancer requires further investigation.
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PMID:The effect of radiation therapy and hyperthermia on a human prostatic carcinoma cell line grown in athymic nude mice. 199 25

The objective of this study was to test the hypothesis that androgen administration prior to chemotherapy (androgen priming) may potentiate tumor cytotoxicity in hormone-responsive prostate cancer. Accordingly, six groups of Copenhagen rats bearing small (i.e., 40-mm3 median volume) Dunning R3327 G tumors were left untreated or received castration, chemotherapy, or a combination of the two, with or without androgen priming. Groups without priming included: intact untreated, castrate alone, intact plus chemotherapy, and castrate plus chemotherapy (cyclophosphamide, 30 mg/kg/day, for 2 days, with repeat cycle in 24 days) (Cx). To specifically evaluate the effect of androgen priming on Cx cytotoxicity, two additional castrate groups were studied. One received testosterone propionate (4 mg/kg/day) for 2 days prior to Cx and the other after Cx. Treatment effect was evaluated by quantitating tumor volume as well as animal survival to an ethically allowable, maximal tumor burden. As expected, castration and Cx produced a retardation of tumor growth and prolongation of survival when compared to untreated animals. The addition of androgen priming prior to but not after Cx enhanced the degree of tumor suppression. Specifically, 26 days after the second Cx cycle, all androgen-primed tumors had regressed; 70% of tumors had disappeared and those remaining were barely palpable. At this same time point, tumors in all the other groups were actively growing and had volumes greater than initial values (P less than 0.01). Although tumor regrowth occurred, median survival for the androgen-primed group was significantly prolonged, to 186 days versus 39 days (P less than 0.01) for untreated animals and 153 days for the non-primed castrate plus Cx animals (P less than 0.01). These data suggested that androgen priming potentiates the effects of Cx in castrate animals bearing R3327 G tumors.
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PMID:Beneficial effects of androgen-primed chemotherapy in the Dunning R3327 G model of prostatic cancer. 200 59

A series of experiments were conducted to evaluate the effects of Win 49,596, a novel steroidal androgen receptor antagonist, in animal models of prostate cancer. In the first experiment, oral administration of Win 49,596 at doses of 30, 100, or 300 mg/kg/day for 28 days inhibited (P less than 0.05) the growth of the androgen-sensitive PAP variant of the Dunning R-3327 prostatic carcinoma in intact male rats relative to intact controls. The degree of inhibition at 100 and 300 mg/kg/day Win 49,596 was similar (P greater than 0.10) to that observed in castrate controls as well as in intact rats administered the nonsteroidal androgen receptor antagonist flutamide orally at 15 mg/kg/day. Castration as well as treatment with either Win 49,596 or flutamide also decreased (P less than 0.05) the weight of the prostate in tumor-bearing animals. Additional studies were conducted to determine the effect of Win 49,596 on the growth of the androgen-dependent PC-82 human prostatic carcinoma xenografted into athymic nude male mice. Oral administration of Win 49,596 at 30, 100, or 300 mg/kg/day for 35 days inhibited (P less than 0.05) tumor growth relative to intact controls. The degree of tumor inhibition was similar to that observed in intact male mice administered the nonsteroidal androgen receptor antagonist flutamide orally at 30 mg/kg/day but was less than that observed following castration. Ventral prostate weights were also reduced (P less than 0.05) in castrate mice as well as in intact mice administered either Win 49,596 or flutamide. In the last experiment, at equivalent total daily dosages of either 150 or 300 mg/kg/day Win 49,596, twice a day (BID) dosing was more effective than once a day (SID) dosing in inhibiting tumor growth. The inhibitory effects of Win 49,596 at 150 mg/kg BID on tumor growth were similar to those observed following castration. Although Win 49,596 treatment reduced (P less than 0.05) ventral prostate weights relative to intact controls, there was no difference (P greater than 0.10) between SID vs. BID dosing. Based on the results of these studies and subject to further testing, Win 49,596 may have utility in the treatment of hormonally dependent metastatic prostate cancer in humans.
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PMID:Evaluation of Win 49,596, a novel steroidal androgen receptor antagonist, in animal models of prostate cancer. 200 17

Rats bearing Dunning R-3327 hormone-dependent prostate tumors were treated with LH-RH antagonist SB-75 in the form of microcapsules for sustained delivery administered every 3 weeks and which released 24, 48, 72 micrograms/day respectively. The effects were compared with those of microcapsules of the agonist D-Trp-6-LH-RH releasing 25 micrograms/day. Both types of LH-RH analogs significantly inhibited tumor growth over a period of treatment lasting 8 weeks. The effect of SB-75 was dose-dependent. The total inhibition of spermatogenesis, as well as atrophic signs in the prostate and seminal vesicles, demonstrated a marked suppression of the pituitary-gonadal system by these analogs. The histological signs of tumor regression were analyzed. The vascular content of tumors did not change after the treatments, but an increased amount of connective tissue was found in the treated tumors, especially after administration of SB-75. Both the agonist and the antagonist caused a moderate decrease of the number of mitotic cells and a marked increase of apoptosis in the tumors. The apoptotic index, i.e. the percentage of tumorous glands showing signs of apoptosis, reached 40-50% in treated groups, compared to only 15% in controls. An apoptotic index of 60% was noted in a separate group of rats treated with 200 micrograms SB-75/animal/day for 3 days. The signs of enhanced apoptosis disappeared 1 week after the short-term treatment. The induction of apoptosis by LH-RH analogs seemed to be of greater importance in tumor growth inhibition than their antimitotic effect. These results extend our previous observations on the efficacy of LH-RH antagonists in inhibition of various cancers. This histopathologic evaluation clearly supports our contention that modern antagonists of LH-RH, free of edematogenic effects, inhibit the growth of Dunning prostate tumors. Because of the immediate inhibitory effects, the use of LH-RH antagonists might lead to an improvement in the clinical response in patients with prostate cancer.
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PMID:Histological changes in Dunning prostate tumors and testes of rats treated with LH-RH antagonist SB-75. 202 Jun 21

Death related to prostate cancer is invariably due to the tumor metastasis (to lungs, skeleton and lymph nodes). Tumor cell metastatic behaviour is still poorly understood. The R3327 prostate tumor model in the male Copenhagen rat offers an opportunity to investigate the different aspects of metastatic processes in vivo and to evaluate effects of current and new treatment approaches. Lymphatic spread of cancer cells can be measured by determining volume of local load in successive draining lymph node stations. Surgical removal of primary tumor and inguinal lymph node shows that lymphatic metastasis in the R3327-MATLyLu tumor variant is a continuous progressive phenomenon, which starts already in early stages of tumor growth after subcutaneous transplantation. Spread to the lungs can be quantified by enumeration of macroscopically visible pleural lung colonies. Metastatic spread to the lungs can be mimicked by intravenous injection of monodispersed tumor cell suspension. Within 10 days pleural tumor colonies become visible. Effects of different agents and treatments like chemotherapeutic drugs, heparin, surgery and high energy shock wave (HESW) treatment have been described using these methods. Recently, metastasis to the vertebral column was induced by temporal occlusion of venous blood flow through the caval veins while injecting tumor cells in the lateral tail vein. The resulting osteoblastic metastatic lesions in the lumbar vertebrae and the concomitant spinal cord compression led in time to the loss of motoric and sensory function of the hind legs. These observations permit investigation of the mechanisms of bone metastasis based on biological functions, i.e. sensory and motoric function of the hind legs. Finally, it can be said that the various variants of the R3327 rat prostate tumor offer an appropriate model to study various aspects of prostate cancer and metastasis.
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PMID:Factors in prostate cancer metastasis. 224 Nov 6

The present review is concerned with the value of bone scanning in the follow-up of patients with malignant tumors. The scintigraphic sensitivity depends on the type of bone metastases. Osteoplastic metastases (e.g., from prostatic cancer) can be detected much more easily than purely osteolytic foci (e.g., of multiple myeloma). One controversial point is the role of bone scans in the follow-up of patients with breast carcinoma. This particular malignancy is used as an example to point out irrationalities in the recommendations on the selection of imaging modalities in routine follow-up. Such recommendations are based on the present knowledge of the tumor growth kinetics, which is still inadequate. In view of this, follow-up strategies should not be based solely on statistical and epidemiological considerations and cost-benefit ratios.
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PMID:[The importance of bone scintigraphy in the aftercare of patients with malignancies]. 225 52

A current hypothesis suggests that androgen administration prior to chemotherapy (androgen priming) may potentiate tumor cytotoxicity in prostate cancer. The Dunning R3327G rat prostatic tumor model was used to test this concept experimentally. Control groups without priming included (1) intact untreated, (2) castrate alone and (3) castrate+ chemotherapy (cyclophosphamide, 30 mg/kg/day for 2 days with repeat cycle in 25 days- CTX). Two experimental groups received androgens, one before and one after chemotherapy. Treatment effect was monitored by quantitating tumor volume and animal survival. Control groups receiving castration and chemotherapy had a retardation of tumor growth and a prolongation of survival when compared to untreated animals. Androgen priming before but not after chemotherapy enhanced the degree of tumor suppression. With the androgen-priming protocol, all androgen-primed tumors had regressed, 3/6 tumors had disappeared and 3 were only palpable. At the same time point, tumors in all the other groups were actively growing and had volumes greater than the initial values (P less than 0.01). Median survival was significantly prolonged in primed animals 191 vs 40 days for untreated animals and 150 days for the nonprimed castration + chemotherapy animals (P less than 0.02). These findings have been repeated with several replicate experiments. These observations confirm the hypothesis that androgen priming can potentiate chemotherapy in an experimental system.
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PMID:Androgen-primed chemotherapy-experimental confirmation of efficacy. 228 85

Based upon a large body of experimental and clinical data, it is evident that multiple malignant events are necessary for a normal cell to give rise to a fully malignant cancer cell. A critical issue with regard to human prostatic carcinogenesis is the clinical significance of the large number of cancers that are present histologically in the elderly male prostate gland. A possibility is that these histological prostate cancers already have undergone all of the malignant events necessary to produce clinically manifest cancer and, thus, only further tumor growth is required to produce a clinical tumor. Alternatively, these histological cancers may have undergone some but not all of the events necessary to produce clinical disease and, therefore, despite host longevity the cancer will remain clinically silent as long as no further malignant changes occur. This issue has importance clinically with respect to the diagnosis, therapy and possible prevention of prostatic cancer. Clinical observations and the mathematical relationship between prostate cancer prevalence and host age (time) support the fact that, in addition to growth, histological prostate cancer requires further malignant events to produce clinical disease. A better understanding of the events involved in prostate cancer development will be necessary to have a greater impact on this disease in the future.
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PMID:Clinical evidence for and implications of the multistep development of prostate cancer. 231 98


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