Patterns and fate of PSA bouncing following 3D-CRT

doi:10.1016/S0360-3016(01)01557-7

International Journal of Radiation OncologyBiologyPhysics

Volume 50, Issue 4, 15 July 2001, Pages 845-849

https://doi.org/10.1016/S0360-3016(01)01557-7 Get rights and content

Abstract

Purpose: The goals of this study were to quantify the frequency of post-treatment prostate-specific antigen (PSA)-level bouncing following three-dimensional conformal radiation therapy (3D-CRT) for prostate cancer and to identify any relationships that may exist between bouncing activity and biochemical control (bNED).

Methods: Between May 1989 and July 1995, 306 patients were treated with 3D-CRT alone. All patients had 6 or more post-treatment PSA levels and at least 5 years of PSA follow-up. The median total follow-up and total dose to the center of prostate was 79 months and 74 Gy, respectively. A bounce was defined by a minimum rise in PSA of 0.4 ng/mL over a 6-month period, followed by a drop in PSA of any magnitude. Estimates of bNED control rates were made using Kaplan–Meier methodology and comparisons were made using the log-rank test. Multivariate analysis of bNED control predictors was accomplished using a stepwise Cox proportional hazards model.

Results: Nearly one third of the patients experienced at least one bounce. Bouncers were found to present with higher pretreatment PSA levels and were treated with lower dose levels to the center of prostate. Five-year bNED control estimates for nonbouncers vs. bouncers were 69% and 52%, respectively (p = 0.0024). After controlling for dose and pretreatment PSA level, total number of bounces emerged as a significant predictor of bNED control (p = 0.02).

Conclusions: Bouncing PSA levels occur in approximately one third of the patients treated with 3D-CRT alone, with bouncing occurring at a constant rate from 2 to 5 years post-treatment. Bouncing is associated with lower radiation dose levels, higher pretreatment PSA levels, and decreased bNED control. Nearly half of the bouncers are bNED controlled; thus, clinicians should not use bouncing as a sole indicator of relapse.

Introduction

Prostate-specific antigen (PSA) is a glycoprotein serine protease specific to prostatic tissue that has been established as a sensitive marker for the monitoring of the status of prostate cancer (1). In men treated with radiation therapy, post-treatment PSA levels fall to low but usually detectable levels following treatment, and relapse has been measured by some definition of a post-nadir rise. Accordingly, clinicians monitor tumor response and relapse by observing trends in serial PSA determinations following therapy and applying various empirical rules for biochemical failure. In 1997, the Board of Directors of the American Society for Therapeutic Radiology and Oncology (ASTRO) charged a committee to confer and evaluate the role of PSA post-radiation, concluding that three consecutive increases in PSA level is the most appropriate definition of biochemical failure following radiation therapy (2). They agreed that the use of three consecutive levels, as opposed to two, reduces the risk of falsely declaring biochemical failure due to bouncing PSA levels (as defined by a transient increase in PSA level followed by a decline).

Even after resolving the issue of an appropriate definition of PSA failure, a single rise in PSA level post-treatment continues to be the source of significant anxiety for both clinicians and patients. The ambiguity surrounding PSA bouncing and its relationship to disease relapse is therefore also a source of considerable anxiety. The purpose of this study was to quantify the frequency of bouncing following 3D-CRT for prostate cancer and to identify any relationships that may exist between bouncing activity and biochemical control (bNED control).

Section snippets

Methods and materials

Between May 1989 and July 1995, 306 men treated at Fox Chase Cancer Center for localized prostate cancer met the following criteria: all had a pretreatment PSA level, at least 6 post-treatment PSA levels, a minimum of 5 years PSA follow-up, and were treated using three-dimensional conformal radiation therapy (3D-CRT) alone. All patients were staged prior to treatment with a directed history and physical examination, including digital rectal examination (DRE), routine blood studies, and

Results

For the 306 patients, 2,886 PSA levels were available within 5 years of treatment, yielding an average of 9 readings per patient for bouncing categorization. Ninety-five (31%) patients demonstrated bouncing activity, with the total number of bounces equaling 125. Specifically, 71 patients experienced a single bounce, 19 patients experienced 2 bounces, 4 patients experienced 3 bounces, and 1 patient experienced 4 bounces. The median slope that prompted the categorization of a bounce was 0.14

Discussion

Bouncing post-treatment PSA levels occur frequently in men treated with 3D-CRT. This phenomenon appears to be related to pretreatment PSA as well as to radiation dose. The median total dose in our patient population was 74 Gy and we observed bouncing activity in approximately one-third of our patients. Based on this study, it appears that institutions treating to lower dose levels will observe a higher fraction of patients who bounce.

The median time to bounce occurred at nearly 3 years

Acknowledgements

The authors would like to acknowledge Ruth Peter, R.N., Clinical Manager of the Prostate Cancer Data Base, for her efforts in the collection and quality assurance of these data.

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Rapid communicationPatterns and fate of PSA bouncing following 3D-CRT

Abstract

Introduction

Section snippets

Methods and materials

Results

Discussion

Acknowledgements

Int J Radiat Oncol Biol Phys

J Urol

Prognostic importance of prostate specific antigen for monitoring patients with stages B2 to D1 prostate cancer

Cancer Res

Consensus statementGuidelines for PSA following radiation therapy

Int J Radiat Oncol Biol Phys

Rapid communication
Patterns and fate of PSA bouncing following 3D-CRT