ABSTRACT
Introduction: Most international clinical practice guidelines for prostate cancer (PCa) are driven by data derived in a Western setting. However, tumour biology and clinical disease progression are likely to differ in the Asian population. We compare the performance of the revised American Joint Committee on Cancer (AJCC) prognostic groups with the commonly used D’Amico Risk Classification and conventional predictors for PCa, in a large cohort of Asian patients.
Materials and Methods: We retrospectively reviewed data for 404 consecutive Singaporean patients receiving definitive radiotherapy at our centre between December 1996 and October 2006. The primary outcome was biochemical relapse-free survival (BRFS), defined using the Phoenix definition. The secondary outcome was overall survival (OS). Prognostic risk groups were defined using AJCC 7th edition (AJCC7) and 6th edition (AJCC6). Univariate analysis (UVA) and multivariate analysis (MVA) were performed for the following putative risk factors: age, Gleason score, prognostic grouping, tumour classification, radiation delivery technique, radiotherapy dose, hormonal therapy and initial PSA value. Results: For the cohort, median age was 69 years. Median follow-up was 66.3 months. Five-year BRFS rate was 84.3% with 71 biochemical relapses and 5-year OS rate was 89.1% with 54 deaths. The concordance-indices for BRFS prediction were 0.588, 0.550 and 0.567 for AJCC7, AJCC6 and D’Amico respectively. Initial PSA, T-stage and AJCC7 were prognostic for BRFS on UVA. Comparison of AJCC7 vs. D’Amico showed no statistical additional value of either classification system although D’Amico was superior when compared to AJCC6 in predicting BRFS. T-stage ≥3 and D’Amico were significant prognostic factors for BRFS on MVA. Conclusion: In our local, predominantly Chinese population, neither AJCC6 nor AJCC7 demonstrated a high predictive accuracy for BRFS although AJCC7 has a slightly better predictive ability than AJCC6.Prostate cancer (PCa) is the second most frequently diagnosed cancer in men, with a worldwide incidence of approximately 900,000 in 2008. Internationally, there is marked variation in incidence, ranging from 104.2 per 100,000 in some Western populations, to 4.1 per 100,000 in South and Central Asia. However, there has recently been a reported increase in incidence and mortality from PCa in various Asian countries. In Singapore, the age-standardised incidence rates (ASIR) have risen from 8.3 per 100,000(1983 to 1987) to 23.9 per 100,000 (2003 to 2007) in just 20 years. The ASIR in Singapore has reached 28.7 per 100,000, more than double that in Shanghai, China (ASIR of 11.3 per 100,000) or Mumbai, India (ASIR of 11.5 per 100,000). This may be attributed in part to increased PSA screening, the availability of transrectal ultrasound and extended sextant biopsies for prostate cancer detection in the late 1990s, although there may be other still unknown contributing factors.
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