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Biomedical subjects

M E Gleave

Publications and source records attributed to M E Gleave.

At least 19 recordsLinked to original sources
PubMed1998

Butyrate analogue, isobutyramide, inhibits tumor growth and time to androgen-independent progression in the human prostate LNCaP tumor model.

Progression to androgen independence remains the main obstacle to improving survival and quality of life in patients with advanced prostate cancer. Induction of differentiation may serve as a rational basis for prevention of progression to androgen independence by modulating gene expression activated by castration or upregulated during androgen-independent progression. The objectives of this study were to characterize the in vitro effects of sodium butyrate on human prostate cancer cell growth, PSA gene expression, and differentiation in the LNCaP tumor model and to determine whether tumor progression in vivo is delayed by isobutyramide, an orally bioavailable butyrate analogue with a longer half-life. The effects of isobutyramide on LNCaP tumor growth and serum PSA levels in both intact and castrate male mice were compared to controls. At concentrations >1 mM, butyrate induced dose-dependent changes towards a more differentiated phenotype, G1 cell cycle arrest, and an 80% decrease in LNCaP cell growth rates. PSA gene expression was increased threefold by butyrate, indicative of differentiation-enhanced gene expression. The half-life of isobutyramide in athymic mice was determined by gas chromatography to be 4 h. During a 4 week period in intact-placebo mice, tumor volume and serum PSA increased 4.1- and 6.6-fold, respectively, compared to twofold and 2.7-fold increases in tumor volume and serum PSA in intact-treated mice. During a 7 week period in castrate-placebo mice, tumor volume and serum PSA levels increased 2.4-fold and fourfold, respectively, compared to a 50% reduction in tumor volume and a twofold increase in serum PSA above nadir levels in castrate mice treated with adjuvant isobutyramide. Isobutyramide treatment induced pronounced morphological changes in LNCaP tumor cells, with loss of defined nucleoli and dispersion of chromatin distribution. LNCaP tumor PSA mRNA levels actually increased threefold, indicative of differentiation-enhanced gene expression. This study demonstrates that butyrate causes LNCaP cell cycle arrest and increased PSA gene expression, both indicative of differentiation. The combination of castration and adjuvant isobutyramide was synergistic in delaying tumor progression. Decreased tumor cell proliferation and increased PSA gene expression induced by isobutyramide results in disconcordant changes in serum PSA and tumor volume and reduces the utility of serum PSA as a marker of response to therapy.

Administration, Oral↗
PubMed1998

Interferon gamma-1b compared with placebo in metastatic renal-cell carcinoma. Canadian Urologic Oncology Group.

BACKGROUND: Most trials of immunomodulators in metastatic renal-cell carcinoma have been uncontrolled and subject to selection bias. The objective of this blinded, placebo-controlled study was to compare overall response rates, time to disease progression, and survival of patients with metastatic renal-cell carcinoma treated with recombinant human interferon gamma-1b or placebo. METHODS: Patients with biopsy-proved metastatic renal-cell carcinoma were randomly assigned to receive interferon gamma-1b (60 microg per square meter of body-surface area subcutaneously once weekly) or placebo. The primary tumor had been treated by nephrectomy or angioinfarction at least three weeks previously. Patients were evaluated for radiologic evidence of progression, and all responses were independently reviewed by a committee that was unaware of the treatment. RESULTS: A total of 197 patients with metastatic renal-cell carcinoma were enrolled at 17 centers in Canada. One hundred eighty-one patients could be evaluated; of these, 91 were assigned to receive interferon gamma-1b and 90 were given placebo. The groups were well balanced in terms of prognostic factors. Two thirds of all patients had Karnofsky scores of 90 or 100, and more than half had two or more metastatic sites. Grade I and II toxicity, mostly chills, fever, asthenia, or headaches, was reported in 91 percent and 61 percent, respectively, of the patients in the interferon group, as compared with 76 percent and 63 percent in the placebo group. Life-threatening drug-related events were rare, occurring in 1 percent of patients in the interferon group. No significant differences between groups were observed in overall response rates, time to disease progression, or survival. The overall response rate was 4.4 percent (3.3 percent complete response and 1.1 percent partial response) in the interferon group and 6.6 percent (3.3 percent complete response and 3.3 percent partial response) in the placebo group (P=0.54), with a rate of durable complete response of 1 percent in both groups. The median time to disease progression was 1.9 months in both groups (P=0.49), and there was no significant difference in median survival (12.2 months with interferon vs. 15.7 months with placebo, P=0.52). CONCLUSIONS: No difference in outcome was observed in patients with metastatic renal-cell carcinoma who were treated with interferon gamma-1b as compared with placebo. These results emphasize the necessity of testing the efficacy of immunomodulators in randomized studies.

Adjuvants, Immunologic↗
PubMed1998

Transurethral electrovaporization of the prostate versus transurethral prostatic resection: a comparison of postoperative hemorrhage.

OBJECTIVES: To determine the acute and delayed hemorrhage rate of transurethral electrovaporization of the prostate (TEVP) versus standard transurethral resection of the prostate (TURP). METHODS: A retrospective review of 524 consecutive patients who underwent TURP and 302 consecutive patients who underwent TEVP was conducted. The indications for both procedures were identical and based on history, physical examination, American Urological Association symptom score, and uroflowmetry. Parameters of evaluation included the incidence of both initial and delayed hemorrhages, the time until a delayed bleed occurred, blood transfusion rates, and the average length of stay in hospital after a bleed. RESULTS: The overall hemorrhage rate for TURP and TEVP was 4.8% and 4.0%, respectively. In the TURP group, there was a 1.1% incidence of acute bleeds and 3.6% incidence of delayed bleeds. For the TEVP group, 0.3% had an acute hemorrhage, and 3.6% were readmitted for clot retention. The average length of time from original discharge to readmission was 12.9 days for the TURP group with a mean repeat stay of 5.7 days. For the TEVP group, the average interval to readmission was 15.4 days with a stay of 3.1 days. CONCLUSIONS: The overall rate of hemorrhage for the TEVP group was slightly lower than for the TURP group due to fewer acute bleeds. However, the incidence of delayed bleeds and clot retention between the two was identical at 3.6%. Because of improved hemostasis intraoperatively with similar functional results in the long term as shown by other investigators, we foresee TEVP continuing as a viable alternative to TURP.

Acute Disease↗
PubMed1998

Retroperitoneal lymphadenectomy for post-chemotherapy residual masses: is a modified dissection and resection of residual masses sufficient?

OBJECTIVE: To determine if post-chemotherapy retroperitoneal lymphadenectomy for residual masses can be limited to resection of the residual masses and a modified template dissection, without loss of therapeutic efficacy. PATIENTS AND METHODS: Between 1985 and 1995, 50 patients underwent one of three types of retroperitoneal lymphadenectomy for a residual mass after cisplatin-based chemotherapy for stages II and III testicular non-seminomatous germ cell tumour. The pre-operative imaging, operative record and pathology reports were reviewed to determine the location of the residual masses and whether tumour, defined as teratoma or viable carcinoma, was within the boundaries of the modified template and/or residual masses. The median (range) follow-up was 56 (1-140) months. RESULTS: Of 39 patients undergoing a bilateral dissection, one (2.6%) with a left testicular cancer had teratoma identified outside the boundaries of the modified template and the residual masses. The nine patients who underwent resection of residual masses and a modified-template dissection were relapse-free at a median follow-up of 55 months. One of two patients undergoing resection of residual mass alone had two recurrences arising from incomplete resection. Four of eight patients undergoing a modified dissection retained ejaculation, compared with seven of 25 (28%) undergoing a non-nerve sparing bilateral dissection. CONCLUSION: This retrospective study suggests that in patients whose tumour markers become normal and have a residual mass after chemotherapy, residual masses can be resected with a modified-template dissection with no significant risk of leaving tumour in the retroperitoneum.

Adolescent↗
PubMed1997

Androgenic induction of prostate-specific antigen gene is repressed by protein-protein interaction between the androgen receptor and AP-1/c-Jun in the human prostate cancer cell line LNCaP.

In exploring the possible mechanisms of androgen independence of prostate-specific antigen (PSA) gene expression, we investigated the effect of elevating AP-1 by both 12-O-tetradecanoylphorbol 13-acetate (TPA) treatment and transfection of the c-Jun expression vector in LNCaP cells. Transcription of PSA is initiated when ligand-activated androgen receptor (AR) binds to a region in the PSA promoter that contains an androgen-responsive element (ARE). It was found that TPA inhibited androgen-induced PSA gene expression by a mechanism that did not alter nuclear levels of AR protein. Overexpression of AP-1 (jun and fos proteins) also inhibited androgen-induced PSA promoter activity. These observations were apparently related to the disruption of AR.ARE complexes as demonstrated by the results of electrophoretic mobility shift assays. Specifically, c-Jun inhibited the formation of AR.ARE complexes and conversely that AR-glutathione S-transferase proteins inhibited the formation of c-Jun.TPA-responsive element (TRE) complexes. Consistent with the inhibitory effect of both proteins, anti-c-Jun antibody blocked the inhibition of AR.ARE complex formation by c-Jun. A similar, but less marked, effect was obtained when anti-AR antibody was used to prevent AR inhibition of c-Jun.TRE complex formation. These findings together with results obtained from co-immunoprecipitation experiments strongly suggest that mutual repression of DNA binding activity is due to direct interaction between the two proteins and that the degree of repression may be determined by the ratio of AR to c-Jun. The mechanism of repression studied in mutant analysis experiments yielded evidence of an interaction between the DNA- and ligand-binding domains of AR and the leucine zipper region of c-Jun. Thus, the AR is similar to other nuclear receptors in its ability to interact with AP-1. This association provides a link between AP-1 and AR signal transduction pathways and may play a role in the regulation of the androgen-responsive PSA gene.

Androgens↗
PubMed1997

A metastatic and androgen-sensitive human prostate cancer model using intraprostatic inoculation of LNCaP cells in SCID mice.

Several metastasizing murine and human animal models for prostate cancer are available. However, these models are androgen-independent and lack differentiated features such as androgen receptor and androgen-regulated gene expression like prostate-specific antigen (PSA). The objective of this study was to develop a metastasizing prostate cancer model with differentiated features using the human LNCaP cell line. Athymic and SCID mice were injected either s.c. or intraprostatically with 1 x 10(6) LNCaP cells. Changes in serum and tumor PSA mRNA levels were determined before and after castration to assess time to androgen-independent progression. Local tumor and metastatic growth was assessed at sacrifice after 12 weeks. Reverse transcription-PCR (RT-PCR) was used to detect circulating LNCaP cells. LNCaP tumor incidence after s.c. injection was 100% (65 of 65) in SCID mice and 80% in athymic mice. No lymph node or distant metastases were observed with s.c. tumors, and RT-PCR for PSA transcripts was negative. Primary tumor incidence after intraprostatic injection was 89% (39 of 44) in SCID mice and 60% in athymic mice. In 10 SCID mice with primary tumors followed for 12 weeks, retroperitoneal or mediastinal lymph node metastases were found in 100%, and microscopic pulmonary metastases were identified in 40%. RT-PCR for PSA transcripts was positive in 3 of 10 mice tested. Serum PSA levels in mice with s.c. and intraprostatic tumors decreased by 65% to nadir levels at 7 and 4 days after castration, respectively. Serum PSA and LNCaP tumor PSA mRNA levels increased to precastration levels earlier in SCID mice with intraprostatic tumors compared to those with s.c. tumors. Intraprostatic injection of LNCaP cells in SCID mice provides a useful animal model to investigate mechanisms of metastasis and to evaluate therapies targeted toward inhibiting the metastatic cascade.

Animals↗
PubMed1997

Early experience with high-intensity focused ultrasound for the treatment of benign prostatic hypertrophy.

OBJECTIVE: To evaluate the safety and effectiveness of high-intensity focused ultrasound (HIFU) in patients with benign prostatic hypertrophy (BPH). PATIENTS AND METHODS: The study comprised 25 patients (mean age 67 years: range 47-84) with BPH treated using the Sonoblate HIFU device. Patients were evaluated before and after one treatment of HIFU using the American Urological Association (AUA) symptom score, peak urinary flow rate (Qmax) and a quality-of-life (QOL) score, and any complications were noted. RESULTS: Five patients with large glands were withdrawn because the failure rate was high in these patients. The remaining 20 patients showed a mean improvements in the AUA symptom score (20.25 to 9.56), Qmax (9.2 to 13.7 mL/s) and QOL score (4.75 to 2.50). There were no major complications. CONCLUSIONS: HIFU is safe, produces minimal side-effects or complications and relieves the symptoms of prostatism.

Aged↗
PubMed1997

Neoadjuvant androgen withdrawal therapy decreases local recurrence rates following tumor excision in the Shionogi tumor model.

PURPOSE: The role of neoadjuvant androgen withdrawal before radical prostatectomy continues to be defined and remains investigational. It is unknown whether decreases in positive margin rates will translate into lower biochemical and local recurrence rates until long-term followup is available. We determined whether local recurrence rates after tumor excision were less with neoadjuvant compared to adjuvant androgen ablation in the Shionogi tumor model. Androgen withdrawal in this model triggers apoptosis and complete tumor regression but rapidly growing androgen independent tumors inevitably recur after 1 month. Conceptually, the ideal time for excision is after maximal castration induced tumor involution but before outgrowth of androgen resistant clones. MATERIALS AND METHODS: Shionogi tumors were allowed to grow to 1 to 2 gm. before mice were randomly assigned to group 1-tumor excision with wide margins and castration at tumor recurrence and group 2-neoadjuvant castration for 10 days followed by wide excision of the regressed tumor. RESULTS: Tumors recurred locally in 87% of group 1 mice after a median of 17 days (range 6 to 24) and all regressed completely with adjuvant castration. However, androgen independent tumors recurred in 92% of mice after a median of 36 days. In group 2 androgen independent disease recurred in 44% of mice after a median of 40 days. Tumor-free survival was significantly greater in group 2 than in group 1 (56 versus 20%, respectively, p <0.05). Inked surgical resection margins were positive in two-thirds of group 1 and one-third of group 2 mice. CONCLUSIONS: Neoadjuvant androgen withdrawal decreases local recurrence and positive margin rates by 50% after tumor excision in the Shionogi tumor model. Although this model cannot address the issue of effect of neoadjuvant therapy on subclinical metastases, extrapolation of these results to the clinical disease suggests that neoadjuvant therapy may help to decrease not only the positive margin rates but also the subsequent risk of local recurrence following radical prostatectomy.

Animals↗
PubMed1997

[In vitro and in vivo models developed from human prostatic cancer].

The possibility of maintaining and studying human prostatic cancers in an in vitro and in vivo environment has allowed the development of rare but essential tools to study many aspects of the biology of these cancers. Although none of the available models is perfect, the sum of the studies conducted with these models over more than 20 years constitutes the basis for major progress in our understanding of this disease. The most widely used cell lines (cultured in vitro) are PC-3, DU-145 and LNCaP. They are limited by the fact that they are essentially androgen-independent cell lines, derived from metastatic sites. Due to the slow growth of prostatic cancers, it is very difficult to obtain cancer cell lines which can be transplanted in immunodeficient animals (such as athymic mice) and only a few xenografts are currently available, some of which, like PCV-82, LuCaP 23, CWR-22, are androgen-dependent or sensitive. These models can be used to study host-tumour interactions as well as endocrinological interactions, stroma-tumour cell interactions, and to analyse molecular phenomena related to stages of hormone dependence and hormone resistance. In vitro and in vivo models of metastatic prostatic cancer have also been developed and appear to have a crucial impact on the understanding of metastatic mechanisms and new therapeutic approaches. This paper describes the main experimental models developed from human prostatic cancers, their main characteristics, their value compared to clinical cancers and some of the major studies conducted with these models. Due to the exponential progress in molecular biology techniques and oncogenetics, it appears essential to increase the number and diversity of experimental models of prostatic cancer in order to advance research concerning the crucial phenomena occurring during the course of this disease, from oncogenesis to currently incurable metastatic stages.

Androgens↗
PubMed1996

Teratoma in primary testis tumor reduces complete response rates in the retroperitoneum after primary chemotherapy. The case for primary retroperitoneal lymph node dissection of stage IIb germ cell tumors with teratomatous elements.

BACKGROUND: Recent advances in the therapy of advanced testicular nonseminomatous germ cell tumors (NSGCT) have resulted in increased attention to avoiding double therapy in cases where single modality therapy will suffice. METHODS: Over an 8-year period, 104 patients with Stage II and III testicular NSGCT received primary chemotherapy. Seventy-nine patients had retroperitoneal lymph nodal metastases, 33 of whom had a radiologic complete response, 43 a radiologic incomplete response, and 3 were not re-evaluated after induction chemotherapy. Thirty-nine patients underwent retroperitoneal lymph node dissection (RPLND). The radiologic and pathologic response of the nodes to primary chemotherapy was correlated with tumor burden (lymph node metastasis size < or = 2 cm, 2.1-5 cm, 5.1-10 cm, and >10 cm), primary tumor pathology, and prechemotherapy marker levels. RESULTS: Larger initial lymph node size, metastases size, the presence of teratoma in the primary tumor, and prechemotherapy alpha-fetoprotein (alpha-FP) > 80 mg/L and beta-HCG (bHCG) 10000 IU/L were found to correlate significantly with an incomplete radiologic response. Lymph node metastases size was the only independent prognostic factor on multivariable logistic regression analysis. Prechemotherapy alpha-FP > 80 mg/L and beta-HCG > 10000 IU/L were associated with the presence of teratoma or carcinoma in the retroperitoneal nodes. The presence of teratoma in the primary tumor is associated with a higher incomplete response rate and residual teratoma in the retroperitoneal lymph nodes after primary chemotherapy. CONCLUSIONS: Predictors of need for postchemotherapy RPLND include large lymph node metastasis size and presence of teratomatous elements in the primary tumor. To reduce the need for and morbidity of double therapy, patients with low volume clinical Stage II, NSGCT and teratomatous elements in the primary tumor are arguably better served by primary RPLND.

Adolescent↗
PubMed1996

Intermittent androgen suppression delays progression to androgen-independent regulation of prostate-specific antigen gene in the LNCaP prostate tumour model.

In most patients with prostate cancer, continuous androgen suppression (CAS) therapy causes tumour regression and an accompanying decrease in serum prostate specific antigen (PSA). However, with tumour progression, regulation of both tumour growth and PSA gene expression becomes androgen-independent. Because androgen resistance develops, in part, from adaptive cell survival mechanisms activated by androgen withdrawal, we hypothesize that intermittent re-exposure to androgens may prolong time to androgen-independent progression. The objective of this study was to determine whether intermittent androgen suppression (IAS) could delay the onset of androgen-independent PSA gene regulation in LNCaP prostate tumour model when compared to CAS. Five or six cycles of IAS were possible before progression developed. IAS prolonged time to androgen-independent PSA gene regulation from an average of 26 days in CAS to 77 days in IAS. Serum PSA increased above pre-castrate levels in all mice treated with CAS by 28 days post-castration, but remained below pre-castrate levels in 75% of IAS-treated mice by 60 days post-castration. By 15 weeks post-castration, serum PSA levels increased 7-fold above pre-castrate levels in CAS-treated mice compared to 1.9-fold increase in IAS-treated mice. PSA mRNA expression levels highly correlated with serum PSA levels in both groups. Maintenance of androgen dependency through IAS may be due to androgen-induced differentiation and/or down-regulation of androgen-suppressed gene expression.

Androgens↗
PubMed1996

Low-dose cyproterone acetate plus mini-dose diethylstilbestrol--a protocol for reversible medical castration.

OBJECTIVES: To determine whether a low dose of cyproterone acetate (CPA) (50 mg twice a day) with minidose diethylstilbesterol (DES) is efficacious in rapidly reducing and maintaining serum testosterone at less than 10% of pretreatment level and whether the effect is reversible upon cessation of therapy. METHODS: Data were collected prospectively on 62 subjects, aged 50 to 90 years (mean 69) with histologically confirmed prostate cancer and normal serum testosterone levels. Treatment was initiated with CPA 50 mg twice a day plus DES 0.11 mg once a day, both administered orally, and continued or 6 months unless discontinued for reasons unrelated to the study. Subsequent management was at the discretion of the investigator/managing physician. Treatment was discontinued with determination of at least one follow-up testosterone level in 28 patients. RESULTS: Mean pretreatment testosterone level was 13.8 nmol/L (range 4.5 to 46.6, median 14.0, 95% confidence interval [CI] 12.0 to 15.0). Testosterone dropped to a mean of 0.6 nmol/L (range 0.1 to 2.2, median 0.5, 95% CI 0.4 to 0.6) by first follow-up (usually 1 month) in all patients (P <0.001) and remained at this level as long as treatment continued. Testosterone normalized in all subjects whose treatment was discontinued. Side effects were minimal. CONCLUSIONS: An oral dosage of CPA of 50 mg twice a day in combination with a mini-dose of DES results in rapid and reversible reduction in serum testosterone to castrate levels. This regimen minimizes morbidity and monetary costs of therapy and allows the implementation of novel treatment approaches such as intermittent or neoadjuvant withdrawal therapy.

Aged↗
PubMed1996

Ability of serum prostate-specific antigen levels to predict normal bone scans in patients with newly diagnosed prostate cancer.

OBJECTIVES: To determine whether pretreatment serum prostate-specific antigen (PSA) levels in newly diagnosed prostate cancer patients can identify a group with a low probability of osseous metastasis and safely eliminate the need for a bone scan as a routine part of the staging evaluation. METHODS: We retrospectively reviewed 683 patients with prostate cancer between 1990 and 1993. Patients with prior therapy or serum PSA levels obtained longer than 3 months prior to bone scan were excluded. Bone scans were reviewed by two nuclear medicine physicians with a third deciding equivocal cases. RESULTS: Only 6% of 490 evaluable patients had a positive bone scan on initial evaluation. Scans were positive in 0 of 290 (0%) with PSA levels below 10 micrograms/L, 4 of 88 (4.5%) with PSA levels between 10 and 20 micrograms/L, and 24 of 112 (21%) with PSA levels above 20 micrograms/L. Although the risk of a positive bone scan increased with increasing PSA levels, PSA is a poor positive predictor of positive bone scans. The risk of a positive bone scan was 8% (5 of 64 patients) when PSA was between 20 and 50 micrograms/L, and increased to 40% (19 of 48 patients) for PSA levels greater than 50 micrograms/L. In contrast, serum PSA levels below 10 micrograms/L are strong negative predictors of positive bone scans, with no positive scans in 290 patients with PSA levels below 10 micrograms/L. Although the risk of a positive bone scan increased with increasing stage and grade, tumor stage and grade were poor negative predictors of positive bone scans. Up to 4% of patients with clinically confined or well-differentiated to moderately differentiated tumors had positive scans. Scans were positive in 12% of poorly differentiated tumors, but all these patients had PSA levels above 10 micrograms/L. CONCLUSIONS: Our data support the elimination of routine bone scintigraphy in patients with newly diagnosed prostate cancer and PSA levels below 10 micrograms/L. Bone scans are indicated when PSA levels are above 10 micrograms/L, or with T3 or poorly differentiated disease.

Adult↗
PubMed1996

Biochemical and pathological effects of 8 months of neoadjuvant androgen withdrawal therapy before radical prostatectomy in patients with clinically confined prostate cancer.

PURPOSE: A prospective, nonrandomized trial was initiated to determine the duration of neoadjuvant therapy required for prostate specific antigen (PSA) to reach its nadir, evaluate the ability of an ultrasensitive assay to measure decreases in PSA less than 0.2 microgram./l., and characterize the effects of 8 months of neoadjuvant therapy on pathological stage, positive margin rates, proliferation and tumor marker immuno-staining. MATERIALS AND METHODS: We evaluated 50 patients with clinically localized prostate cancer treated by 8 months of reversible androgen ablation before radical prostatectomy. Serum PSA and testosterone levels were measured monthly. RESULTS: Serum PSA decreased by 84% after 1 month and by a further 52% between 3 and 8 months. Using an ultrasensitive assay, serum PSA decreased to undetectable levels (less than 0.1 microgram./l.) or reached its nadir in 22% of the cases after 3 months, 42% after 5 months and 84% after 8 months. Overall, the positive margin rate was 4%. Of the cases 68% were organ-confined and 24% were specimen-confined. The positive margin rate was not increased after reevaluation with cytokeratin, PSA and prostatic acid phosphatase immuno-staining but of 4 cases initially staged as P0 on hematoxylin and eosin evaluation 2 had microscopic foci of cancer with prostatic acid phosphatase staining. Immuno-staining with the proliferation markers proliferation cell nuclear antigen and Ki-67 showed decreased staining in surgical specimens relative to pretreatment needle biopsy specimens, which suggests that outgrowth of androgen independent clones does not develop during prolonged neoadjuvant therapy. CONCLUSIONS: Eight months of neoadjuvant androgen withdrawal therapy results in low positive margin rates and PSA nadir levels. The initial rapid decrease in PSA results from cessation of androgen regulated PSA synthesis and apoptosis, while the ongoing slower decrease reflects decreasing tumor volume.

Androgen Antagonists↗
PubMed1996

Optimal duration of neoadjuvant androgen withdrawal therapy before radical prostatectomy in clinically confined prostate cancer.

Experimental studies have shown that neoadjuvant androgen therapy dramatically reduces the rate of local recurrence after tumor excision. In the clinical setting, a 3-month course of neoadjuvant therapy before radical prostatectomy has been shown to significantly reduce positive margin rates, but follow-up is too short to assess the impact of such therapy on biochemical and clinical recurrence rates. A phase II study using an ultrasensitive assay showed that 8 months of neoadjuvant therapy were required before prostate-specific antigen (PSA) levels to reach their nadir in 84% of study participants. The positive margin rate in this study was substantially lower than those reported in the literature. Importantly, restaging of specimens after prostatic acid phosphatase (PAP) immunostaining did not upstage or increase positive margin rates. In addition, prolonged neoadjuvant therapy did not appear to result in progression of androgen-independent clones. A randomized phase III trial has been initiated to determine whether an 8-month course of neoadjuvant hormonal therapy is superior to a 3-month course in reducing positive margin rates and biochemical recurrences in patients with clinically confined prostate cancer.

Adult↗
PubMed1995

Intermittent androgen suppression in the treatment of prostate cancer: a preliminary report.

OBJECTIVES: To test the feasibility of using intermittent androgen suppression in the treatment of prostate cancer by taking advantage of the reversible action of medical castration. METHODS: Observations were made on a group of 47 patients (clinical Stage D2, 14; D1, 10; C, 19; B2, 2; and A2, 2) with a mean follow-up time of 125 weeks. Treatment was initiated with combined androgen blockade and continued for at least 6 months until a serum prostate-specific antigen (PSA) nadir was observed. Medication was then withheld until the serum PSA increased to a mean value between 10 and 20 ng/mL. This cycle of treatment and no treatment was repeated until the regulation of serum PSA became androgen independent. RESULTS: The first two treatment cycles lasted 73 and 75 weeks, with a mean time off therapy of 30 and 33 weeks and an overall mean percentage time off therapy of 41% and 45%, respectively. The mean time to achieve a nadir level of serum PSA was 20 weeks in cycle 1 and 18 weeks in cycle 2. Serum testosterone returned to the normal range within 8 weeks (range, 1 to 26) of stopping treatment. The off-treatment period in both cycles was associated with an improvement in sense of well-being and the recovery of libido and potency in the men who reported normal or near-normal sexual function before the start of therapy. In 7 patients with Stage D2 disease, the cancer progressed to an androgen-independent state. The mean and median times to progression were 128 weeks and 108 weeks, respectively. Seven patients have died, 1 from a noncancer-related illness, with mean and median overall survival times of 210 weeks and 166 weeks, respectively. CONCLUSIONS: Prostate cancer is amenable to control by intermittent androgen suppression. This approach affords an improved quality of life when the patient is off therapy. It also results in reduced toxicity and cost of treatment and possibly delays tumor progression. Whether survival is affected in a beneficial or adverse way remains to be studied in a randomized, prospective study.

Aged↗
PubMed1994

Derivation of androgen-independent human LNCaP prostatic cancer cell sublines: role of bone stromal cells.

A model of human prostate cancer was established to study cellular interaction between prostate cancer and bone stroma in vivo. In this model, subcutaneous co-injection of 2 non-tumorigenic human cell lines--LNCaP, a prostate cancer cell line, and MS, a bone stromal cell-line--into intact adult male mice resulted in formation of carcinomas that secreted prostate-specific antigen (PSA), a clinically useful human serum prostate cancer marker. In castrated hosts, upon cellular interaction with bone fibroblasts, we observed the progression of these tumors from an androgen-dependent (AD) to an androgen-independent state (AI). We derived 4 LNCaP cell sublines from the chimeric LNCaP/MS tumors: the M subline from intact hosts and the C4, C4-2 and C5 sublines from castrated hosts. The LNCaP sublines had chromosomal markers similar to those of the parental LNCaP cells and distinctly different from those of the MS bone stromal cell line. Although the parental and derived cell lines expressed similar steady-state levels of ornithine decarboxylase transcript, the sublines expressed 5- to 10-fold higher basal steady-state levels of PSA transcript than did the parental LNCaP cell line. The LNCaP sublines formed 13- to 26-fold more soft-agar colonies than the parental LNCaP cell line. The sublines became tumorigenic, yielding an incidence of tumors in intact athymic mice of 7-75%. The LNCaP sublines C4 and C5 (but not the parental and M cell line) formed tumors in castrated hosts when co-injected with bone fibroblasts. A second-generation LNCaP subline, C4-2, was derived from a chimeric tumor induced by co-inoculating castrated mouse with C4 cells and MS cells. We found that C4-2 subline was tumorigenic when inoculated into castrated hosts in the absence of inductive fibroblasts. Moreover, C4-2 was the only subline capable of forming soft-agar colonies when cultured in serum-free medium. In comparison with the parental LNCaP cells, the C4-2 subline expressed lower steady-state levels of androgen receptor (AR) protein and mRNA transcript and lost its androgen responsiveness in vitro. Our results suggest that certain genetic traits of prostate cancer cells may be selected or altered through an "adaptive" mechanism that involves cellular interaction with the bone stromal cells.

Animals↗