PSA Bounce After Radiotherapy May Be Associated With Outcomes in Patients With Prostate Cancer
A temporary rise in prostate-specific antigen (PSA) scores after radiotherapy may have an association with outcomes in patients with prostate cancer, according to the study findings presented by Naghavi et al in the International Journal of Clinical Oncology. Experiencing a PSA bounce was associated with improved biochemical disease-free survival.
PSA bounces are often seen after patients receive radiotherapy and are indicated by a temporary rise in the PSA level by at least 0.1 to 0.5 ng/mL without prostate cancer recurrence after radiotherapy. Although clinicians are familiar with these occurrences, there is still uncertainty regarding whether these rises in PSA levels in patients with prostate cancer are of any benefit in continued management.
There is great interest among researchers on whether PSA bounces are predictors of recurrent cancer or cancer in remission. With that in mind, Naghavi and colleagues set out to determine whether a PSA bounce seen after radiotherapy was a predictor of cancer recurrence or an indication of postirradiation failure.
Study Details
The investigators analyzed the medical records of 691 prostate cancer patients without regional or distant metastases who were treated with external-beam radiation therapy and/or brachytherapy. The median patient age was 69 years (range, 49–87 years).
Patients were categorized as at very low risk, low risk, intermediate risk, high risk, or very high risk in relation to prostate cancer recurrence. Patients with very-low-risk disease and an expected survival of ≥ 20 years, with low-risk disease and an expected survival of ≥ 10 years, or with “favorable” intermediate-risk disease were treated with either external-beam radiation therapy or brachytherapy. The choice of which treatment to use was based upon patient preferences.
Patients were followed every 3 to 6 months with a PSA test for the first 5 years. After that time, they had an annual PSA test. Biochemical failure was defined as a ≥ 2.0 ng/mL rise in PSA above the nadir value, with no subsequent fall in response to antibiotics. The investigators analyzed the association between a PSA bounce and age, Gleason score, type of radiotherapy, androgen deprivation therapy, Sexual Health Inventory for Men score, National Comprehensive Cancer Network recurrence risk group, pretreatment PSA score, and clinical T stage.
Earlier PSA Bounce After Radiation Therapy
The first PSA bounce after radiation therapy was identified at 17 months (95% confidence interval [CI] = 15–18 months). This finding was in contrast to patients who experienced biochemical failure; for them, the median time to a first PSA bounce was 41 months (95% CI = 28–53 months). In total, 33% of patients experienced at least one PSA bounce. The median magnitude was 1.0 ng/mL (range, 0.4–17.0 ng/mL). Patients 70 years and older were more likely to have a PSA bounce. On multivariate analysis, the sole identifiable predictor of a likely PSA bounce was a Gleason score of 6.
Closing Thoughts
Experiencing a PSA bounce was associated with improved biochemical disease-free survival. A PSA bounce occurred sooner after radiotherapy than a recurrence of prostate cancer.
The investigators noted that caution should be used when interpreting a rising PSA after neoadjuvant and adjuvant androgen deprivation therapies. Gradual recovery of testosterone levels after the completion of androgen deprivation therapy may cause the PSA level to rise and is not necessarily indicative of a biochemical recurrence. They also indicated that prostate biopsies should not be completed until 24 to 30 months after the cessation of radiotherapy.
“Because a PSA bounce occurs in a sizeable number of prostate cancer patients treated with radiotherapy, clinicians should make their patients aware of this phenomenon,” concluded the investigators.
Richard B. Wilder, MD, of the Department of Radiation Oncology, Moffitt Cancer Center, Tampa, Florida, is the corresponding author of this article in the International Journal of Clinical Oncology.
The authors reported no potential conflicts of interest.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
