Delayed radiotherapy for patients with localized prostate cancer: validation by propensity score matching

To retrospectively investigate the biochemical outcome following delayed radiotherapy in patients with prostate cancer. From July 2000 to November 2008, 144 consecutive patients with localized prostate cancer underwent radiotherapy and androgen-deprivation therapy. Biochemical progression-free survival was compared in patients who began radiotherapy >6 months (delayed group) with these who began ≤ 6 months (non-delayed group) from diagnosis by biopsy. Treatment selection bias was adjusted by the propensity score method. After a median follow-up of 64 months, the 5-year biochemical progression-free survival of the delayed and non-delayed groups was 87.4% (95% confidence interval, CI=69.7-95.1%) and 96.6% (95% CI=89.6-98.9%), respectively (p=0.03). Delayed radiotherapy was the only independent risk factor for biochemical progression (hazard ratio=3.97, 95% CI 1.07-14.7, p=0.04). The results were validated by propensity score analysis. Delaying radiotherapy by >6 months increases the risk of biochemical progression in patients with localized prostate cancer.