Portal de Periódicos da CAPES

Definitions of biochemical control after permanent interstitial brachytherapy as sole treatment for localized prostate cancer: Interpreting the psa bounce

2004; Elsevier BV; Volume: 60; Issue: 1 Linguagem: Inglês

10.1016/j.ijrobp.2004.07.344

1879-355X

John J. Coen, A.L. Zietman, Joseph A. Grocela, N.M. Heney, Richard K. Babayan,

Venous Thromboembolism Diagnosis and Management

Biochemical control after external beam radiation has recently been readdressed. A multi-institutional analysis suggested the Houston definition (current nadir + 2) is superior to the ASTRO consensus definition. Although ASTRO has been used, biochemical failure is not defined for patients receiving brachytherapy. This analysis explores definitions of biochemical failure and their interactions with PSA bounce after brachytherapy. From 1996 to 2000, a cohort of 101 prostate cancer patients treated with prostate brachytherapy alone were identified who had neither received neoadjuvant/adjuvant androgen deprivation therapy nor external beam radiation. All patients had 3 or more years of follow up. Median follow-up time was 54 months (range 36–86). Median dose was 144 Gy for 79 patients receiving iodine-125 implants and 115 Gy for 22 patients receiving palladium-103. Outcomes assessed included LC, DMFS and bNED. Endpoints used to assess bNED included the ASTRO definition, Houston definition (current nadir + 2ng/ml), and the ASTRO call date modification (3 successive rises with failure scored at the date of the third rise). For all, clinical failure was also included as an event. A secondary analysis assessed the specificity of the ASTRO and Houston definitions with respect to clinical outcome and PSA at last follow-up (LFU). Here, only PSA defined failures were considered. Failures were classified as predictive of clinical failure (CF), being false calls (FC) if the absolute PSA nadir occurred subsequent to the PSA failure date or as consistent with biochemical failure (BF) based on the PSA pattern at LFU. The ASTRO call date events are classified identically to ASTRO events by this study design. PSA bounce prevalence and its impact on the specificity of biochemical failure determination were assessed. PSA bounce was defined as a PSA increase of 0.2 ng/ml with a subsequent decline. At 4 years, the LC and DMFS rates were 96% and 100%, respectively. There were 8 clinical failures. The 4-year bNED rates were 86%, 87% and 91% by the ASTRO, Houston and ASTRO call date definitions, respectively. ASTRO, which employed backdating, resulted in lower early bNED survival and higher late bNED survival beyond median follow-up. The Houston definition resulted in lower late bNED survival. There were no significant differences. There were 40 PSA bounces and only 1 associated clinical failure. Median time to bounce was 18 months (range 7–71) with 1 beyond 3 years. Median bounce height was 0.6 ng/ml (range 0.2–7.5) and 5 (12.5%) were ≥2 ng/ml. With clinical failure excluded, there were 14 PSA-defined failures by ASTRO and 17 by Houston. By ASTRO, there were 7 CFs and 7 BFs. By Houston, there were 6 CFs, 6 BFs and 5 FCs. All FCs were associated with a PSA bounce. In aggregate, 21 patients had PSA defined events by one of these methods. 10 events were scored by both, 4 by ASTRO only and 7 by Houston only. By ASTRO only, 1 had a CF and 3 had low but rising PSAs at LFU (median 1.3 ng/ml). By Houston only, 5 had PSA bounces and 2 had elevated PSAs at LFU with <3 rises (median PSA 3.6 ng/ml). Although there were no significant bNED differences, observations can be made regarding the adequacy of these PSA endpoints. The ASTRO definition demonstrates the problems inherent in backdating. Early failure is overestimated while late failure is underestimated. The Houston definition, though desirable after external beam radiation, may not be appropriate after brachytherapy as PSA bounce is prevalent. There is a high false call rate. The ASTRO call date definition is reasonable despite the prolonged period required for 3 rises. It results in no miscalls, is not prone to the backdating artifact and is a real time method. The definition of PSA failure after brachytherapy requires appraisal in a multi-institutional setting.