[Cost-effectiveness analysis of maximum androgen blockade for Japanese men with advanced prostate cancer].

Kyoto University, Graduate School of Economics.
Gan to kagaku ryoho. Cancer & chemotherapy 05/2007; 34(4):589-95.
Source: PubMed

ABSTRACT Like other countries, Japan is facing the problem of rising medical costs associated with aging of the population, and therefore the cost-effectiveness of medicines has become increasingly important. Maximum androgen blockade (MAB) therapy, which is being widely used for advanced prostate cancer, has proved useful in clinical studies but it requires the additional use of an anti-androgen in contrast with luteinizing hormone releasing hormone agonist (LHRHa) monotherapy, raising a concern about the increase medical costs. Thus, based on the results of a Japanese Phase III study of bicalutamide we performed a cost-effectiveness analysis. We constructed a Markov model to express the changes in prognosis following MAB therapy and LHRHa monotherapy for advanced prostate cancer and the cost and effectiveness (survival) were simulated. As a result, the expected costs of MAB therapy and LHRHa monotherapy were 5,240,000 yen and 3,660,000 yen, respectively, with expected survival durations of 7.45 and 6.44 years. The incremental cost-effectiveness ratio for MAB therapy was 1,560,000 yen/life-year saved, lower than the established threshold (6,000,000 yen/life-year saved), and a sensitivity analysis confirmed the robustness of this result. Therefore, the incremental cost of bicalutamide was considered worth it in view of the therapeutic effect, suggesting that MAB therapy is a highly cost-effective therapy.

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    ABSTRACT: A standard treatment for advanced prostate cancer is androgen deprivation by surgical or medical castration. In theory, however, combined androgen blockade (CAB) with an antiandrogen plus castration should be more effective because castration alone does not completely eliminate androgens in the prostate. Therefore, a number of randomized clinical trials (RCT) were conducted in the 1990s to investigate the efficacy of CAB with an antiandrogen (nilutamide or flutamide) plus castration; however, there were both positive and negative results for the efficacy of CAB. The lack of data on safety, quality of life (QOL) and cost-effectiveness has been a hindrance to the adoption of CAB for the treatment of prostate cancer. Nevertheless, discussion on CAB for the treatment of prostate cancer has continued for over 20 years, which suggests that there remains some hope for this regimen. In the 2000s, clinical research on CAB with the antiandrogen bicalutamide commenced. CAB using this new antiandrogen was found to prolong overall survival (OS) in patients with prostate cancer, with favorable safety profiles and cost-effectiveness, without deteriorating QOL. In this article, we discuss the feasibility of CAB with bicalutamide for the treatment of prostate cancer by reviewing the theoretical background of CAB and then the results of RCT conducted in the 1990s when the usefulness of CAB was assessed.
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    ABSTRACT: O καρκίνος του προστάτη είναι ένα σηµαντικό πρόβληµα υγείας σε ολόκληρο τον κόσµο. Στον δυτικό κόσµο είναι η περισσότερο συχνή µορφή καρκίνου και η δεύτερη αιτία θανάτου από καρκίνο στον ανδρικό πληθυσµό. Η παρατήρηση -ήδη από τη δεκαετία του 1940- ότι η ανάπτυξη του εξαρτάται από τα ανδρογόνα επηρέασε τον σχεδιασµό των θεραπευτικών σχηµάτων έκτοτε. Σήµερα, η ορµονική θεραπεία στον τοπικά προχωρηµένο και µεταστατικό καρκίνο του προστάτη βασίζεται κυρίως στους αγωνιστές-LHRH και τα αντιανδρογόνα. Τα τελευταία χρησιµοποιούνται ως µονοθεραπεία, εισαγωγική ή συµπληρωµατική θεραπεία µε τα LHRH ανάλογα και τα τελευταία χρόνια δοκιµάζονται σε συνδυασµό µε τους αναστολείς της 5-α-ρεδουκτάσης. Τα αντιανδρογόνα ανταγωνίζονται την τεστοστερόνη στο επίπεδο των πυρηνικών ανδρογονικών υποδοχέων εµποδίζοντας άµεσα το βιολογικό αποτελέσµατα της τεστοστερόνης και της διυδροτεστοστερόνης στα όργανα στόχους. Κατατάσσονται σε δύο κατηγορίες µε βάση τη χηµική τους δοµή: τα στεροειδή και τα µη στεροειδή. Τα στεροειδή αντιανδρογόνα είναι συνθετικά παράγωγα της υδρόξυπρογεστερόνης (hydroxyprogeste-rone). Εµφανίζουν διπλή αντιανδρογονική δράση: Στην περιφέρεια αποκλείουν τους ανδρογονικούς υποδοχείς ενώ λόγω της προγεστερονικής δράσης τους αναστέλλουν κεντρικά την απελευθέρωση των γοναδοτροπινών (LH και FSH) µε αποτέλεσµα την µείωση των επιπέδων τόσο της τεστοστερόνης όσο και των οιστρογόνων. Οι κυριότεροι εκπρόσωποι είναι η cyproterone acetate, η megestrol acetate και η chlormadinone. Κανένα από τα τρία δεν έχει µελετηθεί επαρκώς ωστόσο η cypro-terone acetate έχει χρησιµοποιηθεί ευρύτατα στο παρελθόν. Τα µη στεροειδή αντιανδρογόνα έχουν δράση ανταγωνιστών των ανδρογόνων στο επίπεδο του ανδρογονικού υποδοχέα επιτυγχάνουν την παρεµπόδιση της περαιτέρω ανάπτυξης του καρκίνου και κατά συνέπεια την ενεργοποίηση των µηχανισµών της απόπτωσης χωρίς να καταστέλλουν τα επίπεδα της τεστοστερόνης και των οιστρογόνων. Τα διαθέσιµα µη στεροειδή αντιανδρογόνα είναι η Flutamide η Nilutamide και η Bi-calutamide.
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    ABSTRACT: A previously reported, double-blind, randomized, multicenter phase 3 trial in 205 patients with stage C/D prostate cancer compared combined androgen blockade (CAB) with luteinizing hormone-releasing hormone agonist (LHRH-A) plus bicalutamide 80 mg versus LHRH-A plus bicalutamide-matching placebo (LHRH-A monotherapy). The analysis at a median follow-up of 2.4 years indicated that CAB significantly (P<.001) prolonged the time to progression and the time to treatment failure. In the current report, survival data from a long-term follow-up (median, 5.2 years) were analyzed. All deaths irrespective of cause and all prostate cancer-specific deaths were recorded. The data were analyzed using Cox regression analysis and the log-rank test. At a median follow-up of 5.2 years, a significant overall survival advantage was observed in favor of CAB over LHRH-A monotherapy (Cox regression analysis: hazard ratio, 0.78; 95% confidence interval, 0.60-0.99; P=.0498; log-rank test: P=.0425). The difference in cause-specific survival between the 2 groups was not significant. The achievement of a prostate-specific antigen (PSA) nadir concentration<or=1 ng/mL was a prognostic factor for improved survival. More patients attained PSA nadir concentrations<or=1 ng/mL with CAB compared with patients who received LHRH-A monotherapy (81.4% vs 33.7%; P<.001). CAB with bicalutamide 80 mg offered a significant overall survival benefit compared with LHRH-A monotherapy without reducing tolerability in patients with locally advanced or metastatic prostate cancer.
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