Validation of metastasis-free survival as a surrogate endpoint for overall survival in localized prostate cancer in the era of docetaxel for castration-resistant prostate cancer.

BACKGROUND: Prior work from the Intermediate Clinical Endpoints in Cancer of the Prostate (ICECaP) consortium (ICECaP-1) demonstrated that metastasis-free survival (MFS) is a valid surrogate for overall survival (OS) in localized prostate cancer (PCa). This was based on data from patients treated predominantly before 2004, prior to docetaxel being available for the treatment of metastatic castrate-resistant prostate cancer (mCRPC). We sought to validate surrogacy in a more contemporary era (ICECaP-2) with greater availability of docetaxel and other systemic therapies for mCRPC. PATIENTS AND METHODS: Eligible trials for ICECaP-2 were those providing individual patient data (IPD) after publication of ICECaP-1 and evaluating adjuvant/salvage therapy for localized PCa, and which collected MFS and OS data. MFS was defined as distant metastases or death from any cause, and OS was defined as death from any cause. Surrogacy was evaluated using a meta-analytic two-stage validation model, with an R2 ≥ 0.7 defined a priori as clinically relevant. RESULTS: A total of 15 164 IPD from 14 trials were included in ICECaP-2, with 70% of patients treated after 2004. The median follow-up was 8.3 years and the median postmetastasis survival was 3.1 years in ICECaP-2, compared with 1.9 years in ICECaP-1. For surrogacy condition 1, Kendall's tau was 0.92 for MFS with OS at the patient level, and R2 from weighted linear regression (WLR) of 8-year OS on 5-year MFS was 0.73 (95% confidence interval 0.53-0.82) at the trial level. For condition 2, R2 was 0.83 (95% confidence interval 0.64-0.89) from WLR of log[hazard ratio (HR)]-OS on log(HR)-MFS. The surrogate threshold effect on OS was an HR(MFS) of 0.81. CONCLUSIONS: MFS remained a valid surrogate for OS in a more contemporary era, where patients had greater access to docetaxel and other systemic therapies for mCRPC. This supports the use of MFS as the primary outcome measure for ongoing adjuvant trials in localized PCa.

A prognostic index model for predicting overall survival in patients with metastatic castration-resistant prostate cancer treated with abiraterone acetate after docetaxel.

BACKGROUND: Few prognostic models for overall survival (OS) are available for patients with metastatic castration-resistant prostate cancer (mCRPC) treated with recently approved agents. We developed a prognostic index model using readily available clinical and laboratory factors from a phase III trial of abiraterone acetate (hereafter abiraterone) in combination with prednisone in post-docetaxel mCRPC. PATIENTS AND METHODS: Baseline data were available from 762 patients treated with abiraterone-prednisone. Factors were assessed for association with OS through a univariate Cox model and used in a multivariate Cox model with a stepwise procedure to identify those of significance. Data were validated using an independent, external, population-based cohort. RESULTS: Six risk factors individually associated with poor prognosis were included in the final model: lactate dehydrogenase > upper limit of normal (ULN) [hazard ratio (HR) = 2.31], Eastern Cooperative Oncology Group performance status of 2 (HR = 2.19), presence of liver metastases (HR = 2.00), albumin ≤4 g/dl (HR = 1.54), alkaline phosphatase > ULN (HR = 1.38) and time from start of initial androgen-deprivation therapy to start of treatment ≤36 months (HR = 1.30). Patients were categorized into good (n = 369, 46%), intermediate (n = 321, 40%) and poor (n = 107, 13%) prognosis groups based on the number of risk factors and relative HRs. The C-index was 0.70 ± 0.014. The model was validated by the external dataset (n = 286). CONCLUSION: This analysis identified six factors used to model survival in mCRPC and categorized patients into three distinct risk groups. Prognostic stratification with this model could assist clinical practice decisions for follow-up and monitoring, and may aid in clinical trial design. TRIAL REGISTRATION NUMBERS: NCT00638690.

Imaging yield from 133 consecutive patients with prostate cancer and low trigger PSA from a single institution.

AIM: To investigate the yield of imaging in patients with relapsed prostate cancer (PC) with a low trigger prostate-specific antigen (PSA). MATERIALS AND METHODS: This institutional review board (IRB)-approved, Health Insurance Portability and Accountability Act (HIPAA)-compliant retrospective study included all 133 patients (mean age 68 years; range 45-88; median 69 months since original diagnosis; interquartile range [IQR]: 32-139) with hormone-sensitive PC (HSPC, n=28) or castration-resistant PC (CRPC, n=105) and trigger PSA <4 ng/ml, who underwent same-day bone scintigraphy and computed tomography (CT; total 224 time points) at Dana-Farber Cancer Institute from January to December 2013. Clinical and pathological data were obtained by manual review of the electronic medical records. All the included bone scintigraphs and CT images were reviewed by a fellowship-trained oncoradiologist to record the metastatic pattern and any clinically significant non-metastatic findings. RESULTS: Ninety-four of the 133 (71%) patients had metastatic disease (18/28 [64%] with HSPC, 76/105 [72%] with CRPC). Forty-one of the 133 (31%) patients developed new metastatic disease and 23/133 (17%) developed new clinically significant non-metastatic findings. The incidence of osseous, nodal, and visceral metastases, and clinically significant non-metastatic findings was similar across the HSPC and CRPC groups (p>0.05 for all). Fifty-seven of the 133 (43%) patients had findings seen only at CT, of which 37 had new extra-osseous findings. Only 2/133 (2%) had findings at bone scintigraphy not seen at CT, both in areas not covered on CT. CONCLUSION: Imaging frequently demonstrated new metastatic and non-metastatic findings in patients with a low trigger PSA. CT is valuable in these patients because extra-osseous findings not visible at bone scintigraphy are frequently seen.

Multicenter phase II study of trabectedin in patients with metastatic castration-resistant prostate cancer.

BACKGROUND: This multicenter phase II trial evaluated the efficacy and safety of trabectedin in metastatic castration-resistant prostate cancer (CRPC). PATIENTS AND METHODS: Two schedules were evaluated in three cohorts: weekly as 3-h i.v. infusion at 0.58 mg/m(2) for 3 out of 4 weeks (Cohort A, n = 33), and every 3 weeks (q3wk) as 24-h infusion at 1.5 mg/m(2) (Cohort B1, n = 5) and 1.2 mg/m(2) (Cohort B2, n = 20). The primary end point was prostate-specific antigen (PSA) response; secondary end points included safety, tolerability and time to progression (TTP). RESULTS: Trabectedin resulted in PSA declines ≥ 50% in 12.5% (Cohort A) and 10.5% (Cohort B2) of patients. Among men pretreated with taxane-based chemotherapy, PSA response was 13.6% (Cohort A) and 15.4% (Cohort B2). PSA responses lasted 4.1-8.6 months, and median TTP was 1.5 months (Cohort A) and 1.9 months (Cohort B2). The dose of 1.5 mg/m(2) (approved for soft tissue sarcoma) given as 24-h infusion q3wk was not tolerable in these patients. At 1.2 mg/m(2) q3wk and 0.58 mg/m(2) weekly, the most common adverse events were nausea, fatigue and transient neutropenia and transaminase increase. CONCLUSIONS: Two different trabectedin schedules showed modest activity in metastatic CRPC. Further studies may require identification of predictive factors of response in prostate cancer.

Expression of human adenosine deaminase in nonhuman primates after retrovirus-mediated gene transfer.

Primate bone marrow cells were infected with a retroviral vector carrying the genes for human adenosine deaminase (h-ADA) and bacterial neomycin resistance (neor). The infected cells were infused back into the lethally irradiated donor animals. Several monkeys fully reconstituted and were shown to express the h-ADA and neor genes at low levels in their recirculating hematopoietic cells for short periods of time.

Phase II study of sunitinib in men with advanced prostate cancer.

BACKGROUND: This study explored the efficacy and tolerability of sunitinib, an inhibitor of tyrosine kinase receptors, in men with castration-resistant prostate cancer (CRPC). METHODS: Men with no prior chemotherapy (group A) and men with docetaxel (Taxotere)-resistant prostate cancer (group B) were treated with sunitinib. The primary end point was confirmed 50% prostate-specific antigen (PSA) decline. Secondary end points included objective response rate and safety. Serum-soluble biomarkers were measured. RESULTS: Seventeen men were enrolled in each group. One confirmed PSA response was observed in each group, and an additional eight men and seven men had stable PSA at week 12 in groups A and B, respectively. Improvements in imaging were observed in the absence of post-treatment PSA declines. Common adverse effects included fatigue, nausea, diarrhea, myelosuppression and transaminase elevation. Significant changes following sunitinib treatment were observed in serum-soluble biomarkers including soluble vascular endothelial growth factor receptor-2, platelet-derived growth factor aa, placental growth factor and leptin. CONCLUSIONS: Sunitinib monotherapy resulted in few confirmed 50% post-treatment declines in PSA in men with CRPC. Serum markers of angiogenesis confirmed on-target effects of sunitinib. Assessments of radiographic disease status were often discordant with changes in PSA, indicating that alternate end points are important in future trials.

Gene expression in mice after high efficiency retroviral-mediated gene transfer.

A retroviral expression vector (N2) containing the selectable gene, neoR, has been used to determine the optimal conditions for infecting murine hematopoietic progenitor cells at high efficiency. After infected bone marrow cells were introduced into lethally irradiated mice, the presence, stability, and expression of the vector DNA sequences were analyzed either in individual spleen foci 10 days later or in the blood, bone marrow, and spleens of mice 4 months later. When bone marrow cells were cultured in medium containing virus with titers of more than 10(6) colony-forming units per milliliter in the presence of purified murine interleukin-3, more than 85 percent of the resulting foci contained vector DNA. This proviral vector DNA was intact. Efficient expression of the neoR gene was demonstrated in most of the DNA-positive foci examined. The spleens of reconstituted animals (over a long term) contained intact "vector DNA" and the blood and bone marrow expressed the neoR gene in some animals. Thus, a retroviral vector can be used to introduce intact exogenous DNA sequences into hematopoietic stem cells with high efficiency and with substantial expression.

Stable integration and expression of a bacterial gene in the mosquito Anopheles gambiae.

Foreign DNA was successfully introduced into the germline of the African mosquito vector of malaria Anopheles gambiae. Stable integration of genes into the germlines of insects had been achieved previously only in Drosophila melanogaster and related species and required the use of the P element transposon. In these experiments with Anopheles gambiae, the plasmid pUChsneo was used, which contains the selectable marker neo gene flanked by P element inverted repeats. Mosquitoes injected with this plasmid were screened for resistance to the neomycin analog G-418. A single event of plasmid insertion was recovered. Integration appears to be stable and, thus far, resistance to G-418 has been expressed for eight generations. The transformation event appears to be independent of P.

High-level recombinant gene expression in rabbit endothelial cells transduced by retroviral vectors.

By virtue of its immediate contact with the circulating blood, the endothelium provides an attractive target for retroviral vector transduction for the purpose of gene therapy. To see whether efficient gene transfer and expression was feasible, rabbit aortic endothelial cells were infected with three Moloney murine leukemia virus-derived retroviral vectors. Two of these vectors carry genes encoding products that are not secreted: N2, containing only the selectable marker gene neoR, and SAX, containing both neoR gene and an SV40-promoted adenosine deaminase (ADA) gene. The third vector, G2N, contains a secretory rat growth hormone (rGH) gene and an SV40-promoted neoR gene. Infection with all three vectors resulted in expression of the respective genes. A high level of human ADA expression was observed in infected endothelial cell populations both before and after selection in G418. G2N-infected rabbit aortic endothelial cells that were grown on a synthetic vascular graft continued to secrete rGH into the culture medium. These studies suggest that endothelial cells may serve as vehicles for the introduction in vivo of functioning recombinant genes.

TMPRSS2:ERG gene fusion associated with lethal prostate cancer in a watchful waiting cohort.

The identification of the TMPRSS2:ERG fusion in prostate cancer suggests that distinct molecular subtypes may define risk for disease progression. In surgical series, TMPRSS2:ERG fusion was identified in 50% of the tumors. Here, we report on a population-based cohort of men with localized prostate cancers followed by expectant (watchful waiting) therapy with 15% (17/111) TMPRSS2:ERG fusion. We identified a statistically significant association between TMPRSS2:ERG fusion and prostate cancer specific death (cumulative incidence ratio=2.7, P<0.01, 95% confidence interval=1.3-5.8). Quantitative reverse-transcription-polymerase chain reaction demonstrated high ets-related [corrected] gene (ERG) expression to be associated with TMPRSS2:ERG fusion (P<0.005). These data suggest that TMPRSS2:ERG fusion prostate cancers may have a more aggressive phenotype, possibly mediated through increased ERG expression.

No association between a polymorphic variant of the IRS-1 gene and prostate cancer risk.

OBJECTIVE: Insulin receptor substrate-1 (IRS-1) acts as a docking protein between the insulin-like growth factor-1 (IGF-1) receptor and intracellular signaling molecules in the IGF-1 signaling pathway. Accumulating data support a role of IGF-1 in prostate carcinogenesis. We assessed the influence of the most common IRS-1 gene polymorphism (Gly972Arg) on prostate cancer risk, alone and in combination with IGF-1 and other components in the IGF-1 signaling pathway. MATERIALS AND METHODS: In a nested case-control study within the Physicians' Health Study, the IRS-1 polymorphism was assayed from prospectively collected samples from 564 incident prostate cancer cases and 758 controls matched on age and smoking. We calculated relative risks (RR) and 95% confidence intervals (CI) using conditional logistic regression. RESULTS: Among the controls, 0.8% were homozygous (AA) and 12% were heterozygous (GA) for the polymorphic allele. There was no association between carriage of the A allele and total prostate cancer risk (RR = 1.1 95% CI = 0.8-1.5), advanced disease (stage C or D or lethal prostate cancer, RR = 1.3 95% CI = 0.8-2.3), or plasma IGF-1 levels. We explored possible interactions with body mass index and components in the IGF-1 pathway including IGFBP3, PI3k, and PTEN but none of these factors influenced the relation between IRS-1 genotype and prostate cancer risk. CONCLUSIONS: Our data do not support an association between carriage of the variant IRS-1 gene and prostate cancer risk.

Effects of G/A polymorphism, rs266882, in the androgen response element 1 of the PSA gene on prostate cancer risk, survival and circulating PSA levels.

Prostate-specific antigen (PSA) is a protease produced in the prostate that cleaves insulin-like growth factor binding protein-3 and other proteins. Production is mediated by the androgen receptor (AR) binding to the androgen response elements (ARE) in the promoter region of the PSA gene. Studies of a single nucleotide polymorphism (PSA -158 G/A, rs266882) in ARE1 of the PSA gene have been conflicting for risk of prostate cancer and effect on plasma PSA levels. In this nested case-control analysis of 500 white cases and 676 age- and smoking-matched white controls in the Physicians' Health Study we evaluated the association of rs266882 with risk and survival of prostate cancer and prediagnostic total and free PSA plasma levels, alone or in combination with AR CAG repeats. We used conditional logistic regression, linear regression and Cox regression, and found no significant associations between rs266882 (GG allele vs AA allele) and overall prostate cancer risk (RR=1.21, 95% confidence intervals (CI): 0.88-1.67) or prostate cancer-specific survival (RR=0.94, 95%CI: 0.56-1.58). Similarly, no associations were found among high grade or advanced stage tumours, or by calendar year of diagnosis. There was no significant association between rs266882 and baseline total or free PSA levels or the AR CAG repeats, nor any interaction associated with prostate cancer risk. Meta-analysis of 12 studies of rs266882 and overall prostate cancer risk was null.

The impact of comorbidity and PSA doubling time on the risk of death in men experiencing PSA failure following radiation therapy with or with androgen deprivation therapy for unfavorable-risk prostate cancer.

BACKGROUND: The optimal management of men with PSA failure following initial prostate cancer (PC) therapy stratified by comorbidity is unknown. We investigated the impact that PSA doubling time (DT) and comorbidity had on the risk of all-cause mortality (ACM), prostate cancer-specific mortality (PCSM) and other-cause mortality (OCM) following PSA failure. METHODS: Between 1995 and 2001, 206 men with unfavorable-risk PC were randomized to receive radiation therapy alone or in combination with 6 months of androgen deprivation therapy (ADT); 108 men experienced PSA failure and formed the study cohort. Cox and Fine-Gray regression analysis was used to determine whether PSA DT was associated with the risk of ACM and PCSM/OCM, respectively, stratified by comorbidity status using a validated metric. RESULTS: After a median follow-up of 13.71 years following PSA failure, 81 of the 108 men (75%) died. Longer PSA DT was associated with a decreased risk of PCSM in men with no/minimal (adjusted hazard ratio (AHR) 0.33, 95% confidence interval (CI) 0.17-0.65, P=0.001) and moderate/severe comorbidity (AHR 0.014, 95% CI 0.002-0.129, P=0.0002). However, because of the different contributions of the risk of OCM to risk of ACM within comorbidity subgroups, increasing PSA DT was only associated with a decreased risk of ACM in men with no/minimal (AHR 0.69, 95% CI 0.50-0.96, P=0.03) but not moderate/severe comorbidity (AHR 0.95, 95% CI 0.51-1.78, P=0.87). CONCLUSIONS: Both the extent of comorbidity and the PSA DT should be taken into consideration when deciding on appropriate management and/or clinical trial eligibility at the time of PSA failure.

Duration of the anti-androgen in men undergoing 6 months of an LHRH agonist and radiation therapy for unfavorable-risk prostate cancer and the risk of death.

BACKGROUND: Whether adding a first-generation anti-androgen (AA) to a luteinizing hormone-releasing hormone agonist in the radiotherapeutic management of unfavorable-risk prostate cancer (PC) reduces the risk of all-cause and PC-specific mortality (ACM and PCSM) among men within differing comorbidity subgroups is unknown. METHODS: Between 1995 and 2001, 206 men with unfavorable-risk PC were enrolled in a randomized trial comparing radiation with or without 6 months of androgen-deprivation therapy (ADT). Partial AA use (median: 4.2 months) occurred in 29 of the 102 men randomized to ADT. Cox, and Fine and Gray's regressions were used to evaluate the impact of full versus partial AA use on PCSM and ACM-risk within comorbidity subgroups. RESULTS: After a median follow-up of 16.62 years, 156 men died. In men with moderate to severe comorbidity increasing death was observed as treatment transitioned from no to partial to full ADT (P=0.02) with an increased ACM-risk with full versus partial AA use (adjusted hazard ratio (AHR), 2.25 (95% confidence interval (CI), 0.94-5.41); P=0.07); whereas only 1 and no PC deaths occurred in men receiving a partial versus full AA course, respectively. Among men with no or minimal comorbidity there was no decrease in ACM (AHR, 0.97 (95% CI, 0.49-1.91); P=0.92) or PCSM-risk (AHR 0.39 (95% CI 0.07-52.18); P=0.28) in comparing full versus partial AA use. CONCLUSION: Increasing AA use by 2 months does not appear to impact survival in men with localized unfavorable-risk PC and no or minimal comorbidity, but may shorten survival in men with moderate to severe comorbidity, raising concern regarding in whom and for how long the AA should be prescribed.

Impact of symptomatic skeletal events on health-care resource utilization and quality of life among patients with castration-resistant prostate cancer and bone metastases.

BACKGROUND: Data regarding the impact of symptomatic skeletal events (SSEs) on health economics and patient-reported outcomes in men with castration-resistant prostate cancer (CRPC) and bone metastases from a clinical setting are lacking. Hence, this study aimed to quantify the effects of SSEs on health-care resource utilization (HRU), health-related quality of life (HRQoL) and pain in men with CRPC metastasized to bone. METHODS: This cohort study included men with CRPC and bone metastasis treated at a tertiary center during December 1996-July 2015. SSEs, including pathological fracture, radiation to bone, spinal cord compression and bone surgery, as well as HRU were identified retrospectively through medical records and clinical database. A subset of surviving patients completed Functional Assessment of Cancer Therapy-Prostate (FACT-P) and Brief Pain Inventory-Short Form (BPI-SF) questionnaires. The incremental effect of SSEs on HRU was evaluated using multivariable generalized linear regression. Questionnaire scores were compared using effect sizes (ES); ES⩾0.33 indicated meaningful differences between SSE and non-SSE cohorts. Lower scores suggest lower HRQoL and pain. RESULTS: Of the 832 patients, 207 developed ⩾1 SSE (mean 1.5±0.8) during follow-up (median 2.1 years). Radiation to bone was the most common SSE (84.1%). SSE cohort had significantly higher emergency room (incidence rate ratio (IRR)=1.48; P=0.006), outpatient (IRR=1.17; P=0.005) and inpatient (IRR=1.74; P<0.001) visits. Of the 107 eligible survey patients, 103 (96.3%) responded. SSE cohort had lower mean FACT-P functional well-being (17.5 vs 19.8; P=0.158; ES=0.36), higher mean pain severity (2.5 vs 1.6; P=0.048; ES=0.47) and worst pain scores (3.6 vs 2.3; P=0.033; ES=0.50) compared with the non-SSE cohort, indicating meaningful differences between cohorts. CONCLUSIONS: This study demonstrated high economic and HRQoL burden of SSEs. The findings underscore the need for better supportive and disease-modifying treatments for these patients.

Racial variation in prostate cancer incidence and in hormonal system markers among male health professionals.

BACKGROUND: Racial variation in prostate cancer incidence in the United States is pronounced, with African-American men having the highest rates. Whether differences in the distribution of known or suspected risk factors among racial groups explain this variation is unknown. METHODS: We evaluated prospectively the relation between prostate cancer and race among 45 410 U.S. male health professionals aged 40--75 years in 1986. We used multivariable, pooled logistic regression to adjust the rate ratio (RR) for potential dietary and lifestyle risk factors. We also measured circulating levels of steroid hormones, sex hormone-binding globulin, and vitamin D metabolites and length of the androgen receptor gene CAG repeat in a sample of African-American (n = 43), Asian (n = 52), and white (n = 55) participants and assessed variation by race in these possible prostate epithelial cell growth mediators by use of analysis of variance. Statistical tests were two-sided. RESULTS: The age-adjusted RR for prostate cancer was 1.73 (95% confidence interval [CI] = 1.23--2.45) for African-American men compared with white men. After multivariate adjustment, the RR increased to 1.81 (95% CI = 1.27--2.58). The rate of prostate cancer did not differ between Asians and whites. Steroid hormone and 1,25-dihydroxyvitamin D levels did not vary appreciably by race. However, the mean number of androgen receptor gene CAG repeats was lower among African-Americans (mean +/- standard deviation = 20.1 +/- 3.5) than among whites (22.1 +/- 3.1; P =.007) and Asians (22.1 +/- 3.9; P =.009). CONCLUSIONS: Our results confirm the elevated incidence of prostate cancer among African Americans and show that it is not explained by differences in the distribution of possible dietary and lifestyle risk factors in this cohort. Racial variation in length of the androgen receptor gene CAG repeat may explain a small part of the excess risk of prostate cancer among African-American men in this cohort.

Her-2-neu expression and progression toward androgen independence in human prostate cancer.

BACKGROUND: Human prostate cancers are initially androgen dependent but ultimately become androgen independent. Overexpression of the Her-2-neu receptor tyrosine kinase has been associated with the progression to androgen independence in prostate cancer cells. We examined the expression of Her-2-neu in normal and cancerous prostate tissues to assess its role in the progression to androgen independence. METHODS: Prostate cancer tissue sections were obtained from 67 patients treated by surgery alone (UNT tumors), 34 patients treated with total androgen ablation therapy before surgery (TAA tumors), and 18 patients in whom total androgen ablation therapy failed and who developed bone metastases (androgen-independent [AI] disease). The sections were immunostained for Her-2-neu, androgen receptor (AR), prostate-specific antigen (PSA), and Ki-67 (a marker of cell proliferation) protein expression. Messenger RNA (mRNA) levels and gene amplification of Her-2-neu were examined by RNA in situ hybridization and fluorescent in situ hybridization(FISH), respectively, in a subset of 27 tumors (nine UNT, 11 TAA, and seven AI). All statistical tests were two-sided. RESULTS: Her-2-neu protein expression was statistically significantly higher in TAA tumors than in UNT tumors with the use of two different scoring methods (P =.008 and P =.002). The proportion of Her-2-neu-positive tumors increased from the UNT group (17 of 67) to the TAA group (20 of 34) to the AI group (14 of 18) (P<.001). When compared with UNT tumors, tumor cell proliferation was higher in AI tumors (P =.014) and lower in TAA tumors (P<.001). All tumors expressed AR and PSA proteins. Although Her-2-neu mRNA expression was high in TAA and AI tumors, no Her-2-neu gene amplification was detected by FISH in any of the tumor types. CONCLUSIONS: Her-2-neu expression appears to increase with progression to androgen independence. Thus, therapeutic targeting of this tyrosine kinase in prostate cancer may be warranted.

Patient-reported impotence and incontinence after nerve-sparing radical prostatectomy.

BACKGROUND: The age-adjusted rate of radical prostatectomy, the most common treatment of early (nonmetastatic) prostate cancer, increased almost sixfold between 1984 and 1990. This increase was due in part to reported improvements in postoperative sexual potency after the use of newly developed "nerve-sparing" procedures. However, published estimates from physicians of impotence following various types of radical prostatectomy may be low, since not all patients may report treatment-related complications accurately and completely to their doctors. In contrast, direct surveys of patients indicate much higher rates of postoperative sexual and urinary dysfunction. One problem with most physician and patient surveys is that they have been performed retrospectively, and pretreatment impotence and incontinence prevalent in older men cannot be assessed accurately in retrospective studies. PURPOSE: This study was initiated in a cohort of men before they underwent radical prostatectomy to assess treatment-related effects on impotence and incontinence. METHODS: The study population consisted of 94 men enrolled in a cohort study of treatment for early prostate cancer. The patients completed questionnaires about sexual and urinary functions before surgery and at 3 and 12 months after surgery and had adequate information to assess the type of surgical technique used (non-nerve-sparing, unilateral nerve-sparing, or bilateral nerve-sparing). Because items assessing sexual function were inadvertently omitted from the questionnaire in the initial months of the study, information on sexual function for all time periods was available for only 49 men. RESULTS: Compared with men who had not been treated with a nerve-sparing procedure, men who underwent nerve-sparing radical prostatectomy, particularly of the bilateral type, were younger and had better prognostic features, indicating less advanced cancers. Before surgery, nine (75%) of 12 men not treated with a nerve-sparing procedure reported erections that were usually inadequate for sexual intercourse compared with six (33%) of 18 men and one (5%) of 19 men who underwent unilateral and bilateral nerve-sparing prostatectomies, respectively. At 12 months after surgery, most men reported inadequate erections, including 15 (79%) of the 19 men who had bilateral nerve-sparing surgery; unilateral nerve preservation provided no apparent benefit. In general, nerve-sparing surgery was associated with more use of absorbent pads at 3 and 12 months following treatment, and this approach was associated with substantial urinary incontinence at 3 months but not at 12 months following surgery. CONCLUSIONS: Nerve-sparing prostatectomy, particularly when performed unilaterally, improves postoperative sexual function to a lesser extent than previously reported. Because men with preoperative impotence and more advanced cancers receive nerve-sparing surgery less often, some of the previously reported benefit of nerve preservation may be the result of patient selection and not of the technique per se.

Expression of a human complementary DNA for the multidrug resistance gene in murine hematopoietic precursor cells with the use of retroviral gene transfer.

In multidrug resistance, cells become simultaneously resistant to anthracyclines, vinca alkaloids, epipodophyllotoxins, and certain other natural product cytotoxic drugs. Resistance results from synthesis of a multidrug transporter (P-glycoprotein) encoded by the MDR1 gene (also known as the PGY1 gene). In the present study, a retrovirus vector containing a complementary DNA for the human multidrug resistance gene HaMDR1/A was used to transfer the multidrug resistance phenotype to bone marrow cells of the DBA/2J mouse. A high proportion of transduced bone marrow cells showed resistance to both colchicine and vinblastine, as determined by in vitro colony formation of hematopoietic precursor cells. In addition, brief culturing of the cells in a cytotoxic drug following exposure to the retrovirus vector could be used to increase the proportion of bone marrow cell colonies that were resistant. These results may serve as a model for the generation and selection of bone marrow cells resistant to the toxic effects of chemotherapeutic agents in vivo.