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Biomedical subjects

M K Brawer

Publications and source records attributed to M K Brawer.

At least 37 records · Page 2Linked to original sources
PubMed2000

Polyamine depletion therapy in prostate cancer.

The prostate gland has among the highest level of polyamines in the body and prostate carcinomas have even greater elevated polyamine levels. These ubiquitous molecules synthesized by prostate epithelium are involved in many biochemical processes including cellular proliferation, cell cycle regulation, and protein synthesis. These properties have made polyamines a potential target for therapeutic intervention in diseases of excessive cell proliferation such as cancer. However, attempts to limit tumor growth by inhibition of polyamine synthesis have not been very successful since cells have the capacity to take up polyamines from the bloodstream. We report here studies utilizing polyamine depletion by means of a combination of blockade of polyamine synthesis with DFMO (alpha-difluoromethylornithine), an inhibitor of ornithine decarboxylase, the rate limiting enzyme in the polyamine synthetic pathway, and ORI 1202, a novel inhibitor of polyamine transport into the cell. This cytostatic combination, even in the presence of excess extracellular polyamines, significantly slowed the growth of the human tumor cell line PC-3 grown in tissue culture with an EC(50) in the &mgr;M range. Other prostate cell lines were similarly growth inhibited including LNCaP.FGC and DU145. Growth of the PC-3 tumor cell line as a xenograft in nude mice was also slowed significantly by this combination of compounds. Polyamine levels in the tumor were lowered from control tumor levels. This combination therapy could provide an effective and potentially non-toxic therapy for prostate tumors.Prostate Cancer and Prostatic Diseases (2000) 3, 275-279

Journal Article↗
PubMed2000

Complexed prostate specific antigen provides significant enhancement of specificity compared with total prostate specific antigen for detecting prostate cancer.

PURPOSE: Determining serum total prostate specific antigen (PSA) has proved to be a valuable diagnostic aid for detecting prostatic carcinoma, although the lack of specificity has limited its usefulness. Studies indicate that the use of percent free PSA would improve specificity while maintaining sensitivity. Since complexed PSA represents the major proportion of measurable PSA in serum, we determined whether it represents a single test alternative to the use of percent free PSA for the early detection of prostate cancer. MATERIALS AND METHODS: Archival serum was obtained from 385 men with no evidence of malignancy on biopsy and 272 with biopsy confirmed prostate cancer. We determined the concentration and proportion of total, complexed and free PSA. RESULTS: Receiver operating characteristics analysis using total PSA results from all samples (range 0.32 to 117 ng./ml.) indicated that the areas under the curve for complexed PSA alone as well as the free-to-total and complexed-to-total PSA ratios were similar and significantly greater than those for total PSA alone. Within the range of 85% to 95% sensitivity receiver operating characteristics analysis revealed that the specificity of complexed PSA was higher than that of total PSA and equivalent to that of the free-to-total PSA ratio. We noted a similar improvement in specificity in the 4 to 10 ng./ml. total PSA range. Using published cutoff values for complexed, total and percent free PSA when total PSA was in the 4 to 10 ng./ml. range the sensitivity and specificity of complexed and percent free PSA were similar. Within the 4 to 10 ng./ml. total PSA range the population of patients with no evidence of malignancy and complexed PSA below the upper limit was different with respect to total PSA from that with no evidence of malignancy and free PSA greater than 25%. CONCLUSIONS: The measurement of complexed PSA represents an alternative to the use of percent free PSA, although the patient populations identified by the 2 tests are different.

Humans↗
PubMed2000

Prostate cancer: epidemiology and screening.

The challenge continues-to find better methods of screening for prostate cancer, of determining who should undergo needle biopsy, and of predicting who will fail initial therapy. Investigators are looking at the value of neural networks and an array of markers to provide improved screening and prognostic information.

Journal Article↗
PubMed1999

Effect of finasteride and/or terazosin on serum PSA: results of VA Cooperative Study #359.

BACKGROUND: Medical management of benign prostatic hyperplasia (BPH) giving rise to lower urinary tract symptomatology (LUTS) has emerged as the mainstay for first-line therapy. Prostate-specific antigen (PSA) is the most important method of detecting prostate carcinoma. The effect of finasteride on PSA has been widely reported. Little data exist with respect to alpha-adrenergic blocking therapy in men treated for BPH. In the present investigation we set out to evaluate the effect of these two forms of therapy. METHODS: Patients enrolled in the VA Cooperative Study #359 trial were evaluated. This study evaluated men with moderate LUTS owing to BPH in four treatment groups: placebo (P), finasteride (F), terazosin (T), and combination of finasteride plus terazosin (C). Men were recruited at 31 VA medical centers and had a baseline in 52-week PSA determination at the respective sites. RESULTS: There was no significant difference in baseline PSA between four groups (mean range, 2.0-2.9 ng/ml). Statistically significant reduction in PSA levels was observed at 52 weeks in the F and C arms (P < 0.001), whereas significant increases were observed in the T and P arms (P < 0.01). Additionally, there was no significant difference in PSA response between the T and P arms. Thirty percent of men in the C or F arms had more than 40-60% reduction of PSA. In contrast, the majority of men on T or P had less than 40% change in PSA. Only 35% of men on F or C had the expected 40-60% reduction in PSA level. CONCLUSIONS: These data demonstrate no clinically significant effect of T on PSA level. The heterogeneity of PSA response to F may make monitoring patients for the development of prostate cancer problematic.

Adrenergic alpha-Antagonists↗
PubMed1999

Differences in prostate size between patients from University and Veterans Affairs Medical Center populations.

BACKGROUND: Numerous studies on prostatic disease have been performed at Veterans Affairs (VA) Medical Centers. Recent investigations evaluating early detection of prostate cancer provide insight that the average prostate volume may be different between patients with similar clinical findings who are from different hospital settings. The objective of this study was to compare prostate size between men from University and VA Medical Centers. METHODS: Patients were enrolled retrospectively from 1989-1996 from the Urology Clinics at a University and a VA Medical Center. All men underwent transrectal ultrasound-guided sextant biopsy of the prostate owing to either an elevated prostate-specific antigen (PSA) level and/or abnormal digital rectal examination (DRE) detected prior to biopsy. Prostate volume was calculated using the ellipsoid three-diameter formula based on transrectal ultrasound measurements. RESULTS: There were 1,311 men included in the analysis: 717 were from the VA, and 594 were from the University. The average prostate volume was significantly smaller among VA patients both for men with cancer (P = 0.0004) and for men with no evidence of malignancy (P < 0.0001). Overall, the average prostate volume was 38.5 cm3 (median, 32.5 cm3) among men from the VA compared to 46.8 cm3 (median, 39.3 cm3) among men from the University Medical Center. Men from the VA were older (mean +/- SD = 68 +/- 7.3) than men from the University (mean +/- SD = 66 +/- 7.7) (P = 0.004) and there was no significant difference in PSA levels between the two groups of patients (P = 0.11). Intriguingly, the incidence of cancer was significantly lower at the VA (24.5%) compared to the University (35.9%) (P < 0.0001). CONCLUSIONS: The variance in prostate size suggests that there are significant differences between the two patient populations. Proposed factors leading to this discrepancy include differences in socioeconomic factors, environmental factors, and changes in hormonal milieu related to alcohol and tobacco use. These results may have significant implications regarding the interpretation and extrapolation of results from previous studies performed at a single hospital setting.

Black or African American↗
PubMed1999

Strategies for chemoprevention of prostate cancer.

Because prostate cancer has a long latency and high incidence, it is a good target for chemoprevention by agents such as retinoids, antiandrogens, antiestrogens, and vitamin D analogs. Phase II chemoprevention trials are frequently conducted on cohorts of patients with previous cancers or premalignant lesions who are scheduled for prostate cancer surgery; such trials are currently in progress with several agents. Prostatic intraepithelial neoplasia (PIN) can be used as a surrogate endpoint biomarker for prostate cancer incidence. Studies of men with high-grade PIN (HGPIN) are particularly useful in that they require a much smaller cohort of 200-400 patients instead of the 18 000 patients required for typical Phase III trials. Even with a smaller sample size, statistically significant evidence of cancer prevention is achieved due to the high probability of HGPIN progressing to cancer (35-55%). A Bayesian sequential monitoring system allows interim analysis of biomarker modulation as early as the completion of 30 patients. Putting all these strategies together will help inhibit, delay, or modulate the natural history of prostate carcinogenesis.

Journal Article↗
PubMed1999

Pathology and bio markers of prostate cancer.

This session included five presentations in the areas of pathology of precursor lesions and carcinoma of the prostate, the value of determining neovascularity in the diagnosis and staging of prostate cancer, new 'molecular' markers, correlation between pre- and postoperative Gleason scores and a study dealing with transition zone PSA density. The abstracts and talks are summarized in the next few pages.

Journal Article↗
PubMed1999

Prediction of post-radical prostatectomy pathological outcome for stage T1c prostate cancer with percent free prostate specific antigen: a prospective multicenter clinical trial.

PURPOSE: Prostate specific antigen (PSA) exists in bound (complexed) and unbound (free) forms in serum. The percentage of free PSA enhances the specificity of PSA testing for prostate cancer detection. We evaluated the use of percent free PSA preoperatively to predict pathological stage. MATERIALS AND METHODS: A total of 379 men with prostate cancer and 394 with benign prostatic disease 50 to 75 years old were enrolled in this prospective study at 7 medical centers. All subjects had a palpably benign prostate gland, serum PSA 4.0 to 10.0 ng./ml. and a histologically confirmed diagnosis. The Hybritech Tandem PSA and free PSA assays were used. Of the 379 cancer patients 268 (71%) underwent radical prostatectomy. RESULTS: Higher percent free PSA levels were associated with more favorable histopathological findings in prostatectomy specimens. A value of 15% free PSA provided the greatest discrimination in predicting favorable pathological outcome. Organ confined cancer, Gleason sum less than 7 and small tumors (10% or less involvement of the prostate) were noted in 75% of patients with greater than 15% and only 34% with 15% or less free PSA (p<0.001). Multivariate logistic regression analysis revealed percent free PSA to be the strongest predictor of postoperative pathological outcome (odds ratio 2.25), followed by biopsy Gleason sum (2.06) and patient age (1.35). Total PSA was not predictive in this cohort but has been shown in prior studies to be predictive of outcome when a broader range of PSA values is evaluated. CONCLUSIONS: Percent free PSA may be used for risk assessment of the presence (diagnosis) and stage of prostate cancer in men with PSA between 4 and 10 ng./ml. Percent free PSA may be combined with PSA, digital rectal examination and biopsy findings to help predict postoperative pathological stage and grade, and may assist the patient and physician in making more informed treatment decisions.

Aged↗
PubMed1999

Vasectomy and risk of prostate cancer.

Most studies do not support an association between vasectomy and prostate cancer, but a few have suggested a link. Vasectomy is a common birth control method, and prostate cancer is the most frequently diagnosed solid tumor in men, making this a major public health question. This study was specifically designed to determine whether or not vasectomy is associated with risk of prostate cancer. To examine this issue, we conducted a population-based case-control study in King County, Washington. Interviews were completed with men ages 40-64 years newly diagnosed with prostate cancer between January 1993 and December 1996 who were ascertained through the Seattle-Puget Sound Surveillance, Epidemiology, and End Results (SEER) cancer registry (n = 753) and with comparison men without prostate cancer identified from the same general population (n = 703). The odds ratio (OR) for prostate cancer in relation to vasectomy was assessed. The prevalence of vasectomy was similar in cases (39.4%) and controls (37.7%), resulting in no association (adjusted OR, 1.10; 95% confidence interval, 0.9-1.4). There was no consistent evidence that risk varied by the age at which vasectomy was performed, the time since vasectomy, or the calendar period when the vasectomy was performed. The OR in relation to vasectomy was higher in men with less aggressive prostate cancer. Risk estimates did not differ according to age, race, or family history of prostate cancer. This study suggests that vasectomy is not associated with the risk of developing prostate cancer. It also provides evidence that vasectomized men may be more likely to present with earlier-stage, lower-grade prostate tumors.

Adult↗
PubMed1999

Prostate-specific antigen and other serum markers: current concepts from the World Health Organization Second International Consultation on Prostate Cancer.

Serum prostate-specific antigen is credited with dramatic advances in the early detection, screening, and management of men with prostatic carcinoma. There has been more than a twofold increase in the number of men diagnosed during the last decade, and prostate cancer has emerged as the most common non-skin cancer and the second leading cause of cancer death in men. This report summarizes the history and current status of prostate-specific antigen and other serum markers, incorporating consensus opinions from the Second International Consultation on Prostate Cancer held in Paris in June 1999.

Age Factors↗
PubMed1999

Prostate cancer in relation to the use of electric blanket or heated water bed.

Using data from a case-control study conducted in Group Health Cooperative (GHC) of Puget Sound, we examined the relation between the use of electric blankets or heated water beds and the risk of prostate cancer. Cases were 175 prostate cancer patients ages 40-69 years. Controls were 258 male GHC members frequency matched to cases. The odds ratio (OR) for prostate cancer associated with the use of an electric blanket or heated water bed was 1.4 (95% confidence interval (CI) 0.9-2.2). The risk, however, did not tend to be higher with increasing months per year or years of use. This study did not provide clear evidence on the hypothesized association.

Adult↗
PubMed1998

Use of the percentage of free prostate-specific antigen to enhance differentiation of prostate cancer from benign prostatic disease: a prospective multicenter clinical trial.

CONTEXT: The percentage of free prostate-specific antigen (PSA) in serum has been shown to enhance the specificity of PSA testing for prostate cancer detection, but earlier studies provided only preliminary cutoffs for clinical use. OBJECTIVE: To develop risk assessment guidelines and a cutoff value for defining abnormal percentage of free PSA in a population of men to whom the test would be applied. DESIGN: Prospective blinded study using the Tandem PSA and free PSA assays (Hybritech Inc, San Diego, Calif). SETTING: Seven nationwide university medical centers. PARTICIPANTS: A total of 773 men (379 with prostate cancer, 394 with benign prostatic disease) 50 to 75 years of age with a palpably benign prostate gland, PSA level of 4.0 to 10.0 ng/mL, and histologically confirmed diagnosis. MAIN OUTCOME MEASURES: A percentage of free PSA cutoff that maintained 95% sensitivity for prostate cancer detection, and probability of cancer for individual patients. RESULTS: The percentage of free PSA may be used in 2 ways: as a single cut-off (ie, perform a biopsy for all patients at or below a cutoff of 25% free PSA) or as an individual patient risk assessment (ie, base biopsy decisions on each patient's risk of cancer). The 25% free PSA cutoff detected 95% of cancers while avoiding 20% of unnecessary biopsies. The cancers associated with greater than 25% free PSA were more prevalent in older patients, and generally were less threatening in terms of tumor grade and volume. For individual patients, a lower percentage of free PSA was associated with a higher risk of cancer (range, 8%-56%). In the multivariate model used, the percentage of free PSA was an independent predictor of prostate cancer (odds ratio [OR], 3.2; 95% confidence interval [CI], 2.5-4.1; P < .001) and contributed significantly more than age (OR, 1.2; 95% CI, 0.92-1.55) or total PSA level (OR, 1.0; 95% CI, 0.92-1.11) in this cohort of subjects with total PSA values between 4.0 and 10.0 ng/mL. CONCLUSIONS: Use of the percentage of free PSA can reduce unnecessary biopsies in patients undergoing evaluation for prostate cancer, with a minimal loss in sensitivity in detecting cancer. A cutoff of 25% or less free PSA is recommended for patients with PSA values between 4.0 and 10.0 ng/mL and a palpably benign gland, regardless of patient age or prostate size. To our knowledge, this study is the largest series to date evaluating the percentage of free PSA in a population representative of patients in whom the test would be used in clinical practice.

Aged↗
PubMed1998

Repeat ultrasound guided prostate needle biopsy: use of free-to-total prostate specific antigen ratio in predicting prostatic carcinoma.

PURPOSE: Despite being the most useful tumor marker for the diagnosis of patients with prostate cancer, serum prostate specific antigen (PSA) is still hampered by lack of specificity. A negative prostate biopsy is associated with a 20 to 40% incidence of positive repeat biopsy in men with persistently elevated serum PSA levels. We determine whether the free-to-total PSA ratio could be predictive of prostate cancer in men undergoing repeat biopsy. MATERIALS AND METHODS: Archival sera, drawn before the first biopsy, were gathered from 51 men with a total serum PSA of 2 to 15 ng./ml. who underwent repeat prostate needle biopsy for various indications. The percent free PSA was calculated using the Hybritech Tandem-Rt free and total PSA as well as Dianon Systems freet and Hybritech total PSA assays. The free-to-total PSA ratio results between the cancer and noncancer groups were compared using Student's t test. RESULTS: The median Hybritech free-to-total PSA ratio was significantly lower in patients with positive repeat prostate needle biopsy compared to those with negative biopsy (14.9 versus 19.4%, p=0.05). Total PSA as well as the percent Dianon free-to-Hybritech total PSA ratio were not significantly different between the 2 groups of men. CONCLUSIONS: For total PSA in the range of 2 to 15 ng./ml. Hybritech free-to-total PSA ratio appeared to aid in the prediction of cancer on repeat biopsy.

Aged↗