Identifying differences between biochemical failure and cure: incidence rates and predictors.
ABSTRACT Patients treated with radiation therapy (RT) for prostate cancer were evaluated to estimate the length of time required to document biochemical cure (BC) after treatment and the variables associated with long-term treatment efficacy.
2,100 patients received RT alone for localized prostate carcinoma (external-beam RT, n = 1,504; brachytherapy alone, n = 241; or brachytherapy + pelvic radiation, n = 355). The median external-beam dose was 68.4 Gy, and the median follow-up time was 8.6 years. Biochemical failure (BF) was defined according to the Phoenix definition.
Biochemical failure was experienced by 685 patients (32.6%). The median times to BF for low-, intermediate-, and high-risk groups were 6.0, 5.6, and 4.5 years respectively (p < 0.001). The average annual incidence rates of BF for years 1-5, 5-10,11-15, and 16-20 in low-risk patients were 2.0%, 2.0%, 0.3%, and 0.06% (p < 0.001); for intermediate-risk patients, 4%, 3%, 0.3%, and 0% (p < 0.001); and for high-risk patients, 10.0%, 5.0%, 0.3%, and 0.3% (p < 0.001). After 5 years of treatment, 36.9% of all patients experienced BF. The percentage of total failures occurring during years 1-5, 5-10, 11-15, and 16-20 were 48.7%, 43.5%, 6.5%, and 1.3% for low-risk patients; 64.0%, 32.2%, 3.8%, and 0% for intermediate-risk patients; and 71.9%, 25.9%, 1.1%, and 1.1% for high-risk patients, respectively. Increasing time to nadir was associated with increased time to BF. On multivariate analysis, factors significantly associated with 10-year BC included prostate-specific antigen nadir and time to nadir.
The incidence rates for BF did not plateau until later than 10 years after treatment, suggesting that extended follow-up time is required to monitor patients after treatment. Prostate-specific antigen nadir and time to nadir have the strongest association with long-term BC.
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ABSTRACT: We investigated whether earlier PSA failure following prostate brachytherapy is associated with increased rates of distant metastases (DM), prostate cancer-specific mortality (PCSM), and overall mortality. We retrospectively analyzed 2818 patients who underwent brachytherapy±external beam radiation therapy (EBRT)±androgen deprivation therapy (ADT). With median follow-up of 5.52years, 264 patients experienced PSA failure at a median time of 3.25years. Patients were stratified to early vs. late PSA failures at cutoffs of 1.5years, 3years, or 5years, and tested in univariate/multivariate analyses for freedom from DM, cause-specific survival (CSS), and overall survival (OS). Among patients with PSA failures, 69 (26%) patients experienced DM, 47 (18%) PCSM, and 56 (21%) deaths from other causes. Patients with rapid PSA failures demonstrated increased rates of DM, PCSM, and overall mortality, despite higher total BED and longer ADT. In multivariate analysis with a PSA failure interval <3years, the hazard ratio (HR) for DM was 3.92 (95% CI: 2.34-6.55; p=0.000); HR for PCSM was 2.79 (95% CI: 1.45-5.38; p=0.002); and HR for overall mortality was 2.28 (95% CI: 1.50-3.48; p=0.000). Early PSA failure following radiation is a poor prognostic factor, as it is associated with increased DM, PCSM, and overall mortality.Radiotherapy and Oncology 11/2013; · 4.52 Impact Factor