Measurement of weekly prostate specific antigen levels in patients receiving pelvic radiotherapy for nonprostatic malignancies

Study of prostate-specific antigen levels during salvage radiotherapy after prostate cancer surgery

BACKGROUND

Administration of adjuvant or salvage radiotherapy (RT) after prostate cancer (PCa) surgery is supported by clinical evidence and is a widely adopted strategy. On occasion, we detect changes in prostate-specific antigen (PSA) levels, such as a transient elevation or decline, during RT. Thus, we retrospectively investigated the frequency of changes in PSA levels, their associations with histopathological parameters, PSA doubling time (PSADT), and biochemical recurrence (BR) of PCa.

METHODS

This study included 23 consecutive patients who underwent surgery for PCa between 2012 and 2019, received salvage RT without hormone therapy, and exhibited changes in PSA levels during RT. The prostatic bed was irradiated with a total dose of 64 to 66 Gy. BR was defined as consecutive PSA levels exceeding 0.2 ng/mL or having to start hormone therapy because of PSA elevation after salvage RT.

RESULTS

During salvage RT after PCa surgery, PSA levels transiently increased in 11 patients (47.8%) and decreased in 12 (52.2%). When factors associated with BR were examined in patients with transient PSA elevation, seminal vesicle invasion and preoperative PSA values were identified as being statistically significant. When factors for BR were examined in patients with a decline in PSA levels, the Gleason score and PSADT were identified as being significant. Among the cases of a decline in PSA levels during salvage RT, those who received a radiation dose of less than 36 Gy did not experience BR. Similarly, patients who exhibited changes in PSA levels during salvage RT and did not have perineural invasion did not experience BR.

CONCLUSION

This is the first study to examine the histopathological factors possibly affecting BR in patients undergoing salvage RT after PCa surgery. The results indicate that in patients with transient PSA elevation, seminal vesicle invasion is a significant risk factor. On the other hand, in patients with a decline in PSA levels during irradiation, the Gleason score and perineural invasion were found to be potential risk factors for BR. These findings suggest that a thorough examination of postoperative histopathological results may be necessary for the optimal management of patients with PCa.

Predicting biochemical failure and overall survival through intratherapy PSA changes during definitive external beam radiotherapy

PURPOSE

To determine whether intratherapy prostate-specific antigen (itPSA) changes during radiotherapy (RT) predict prostate cancer outcomes.

METHODS AND MATERIALS

We retrospectively identified patients treated with definitive external beam RT without hormonal therapy who had at least two itPSA measurements. We calculated the adjusted ratio of rise (ARR) in itPSA relative to the pretreatment baseline PSA for each patient. This was defined as ln(maximal itPSA + 1)/ln(baseline PSA + 1). We stratified patients according to an ARR of <1 vs. >1.1. This corresponded to an approximately <30% vs. >30% increase in PSA during RT. Univariate and multivariate analyses were performed examining for biochemical failure-free survival (BFFS) and overall survival (OS).

RESULTS

At a median follow-up of 74 months, we identified 307 patients who met our criteria. Univariate analysis revealed that patients with an ARR of <1.1 (n = 182) had statistically significant inferior BFFS and OS compared with those with an ARR of >1.1 (n = 125). The median BFFS and OS for these two groups was 51 vs. 101 months (p = 0.001) and 96 vs. 128 months (p = 0.01), respectively. On multivariate analysis, the effect of ARR on the risk of biochemical failure for patients with an ARR of <1.1 was significant (p = 0.03) only during the first year after RT. In contrast, the effect of the ARR on OS remained significant for a full 5 years (p = 0.05).

CONCLUSION

The results of our study have shown that an ARR of <1.1 predicts for inferior BFFS and OS in patients treated with RT alone. PSA measurement during RT is a novel clinical tool that could be used to identify patients who might warrant more aggressive therapeutic intervention.

Primary radiation therapy for localized prostate cancer

Prostate cancer in men is similar to breast cancer in women; both cancers rank first, respectively, in incidence and are normally responsive to radiation therapy. In addition, advances in mammography help detect earlier breast cancers, and the development and refinement of prostatic specific antigen (PSA) has resulted in early detection of low-stage localized prostate cancers. This has generated debate over the proper management of localized prostate cancer. While there have not been any controlled, prospective, randomized trials of sufficient power to compare the various local therapies, based on the current available data, the three commonly used local modalities, surgery, and external beam radiation therapy and brachytherapy (radioactive seed implant), have similar efficacy controlling the disease up to 10 years in many patients. Technological advances in treatment delivery and planning have improved the treatment of prostate cancer with external-beam radiotherapy using three-dimensional conformal radiotherapy (3DCRT), ultrasound-guided transperineal implant, or intensity-modulated radiotherapy (IMRT), as well as proton or neutron beam based therapies.

Serum PSA evaluations during salvage radiotherapy for post-prostatectomy biochemical failures as prognosticators for treatment outcomes

INTRODUCTION

Serum prostate specific antigen (PSA) levels have proved to be sensitive markers for the diagnosis of prostate cancer. In addition, PSA levels are useful for detecting and monitoring prostate cancer progression after radiotherapy. Serum PSA evaluations during radiotherapy, however, have not been well documented. In this study, we investigate the prognostic value of PSA evaluations during salvage radiotherapy for prostatectomy failures.

METHODS

Forty-one patients with biochemical failures after prostatectomy treated with salvage radiotherapy consented to have their serum PSA levels evaluated at 30 Gy and 45 Gy of irradiation. All 41 patients had negative metastatic workup and pathologically uninvolved pelvic lymph nodes at the time of referral for salvage radiotherapy. Radiation therapy was delivered with 10--25 MV photons, with doses of 59.4--66.6 Gy. No patients received hormonal ablation therapy before irradiation.

RESULTS

The mean follow-up for all patients was 30.9 months. At last follow-up, 28/41 patients (68.3%) were free from biochemical failure, with 20 of 41 patients (48.8%) expressing undetectable PSA levels. Serum PSA evaluations at 30 Gy did not significantly predict for either biochemical (p = 0.0917) or clinical (p = 0.106) disease-free outcome. However, serum PSA evaluations at 45 Gy significantly predicted for both biochemical (p = 0.0043) and clinical (p = 0.0244) disease-free outcomes, with PSA elevations at 45 Gy significantly associated with poor outcomes. On univariate analysis of prognosticators for biochemical failures, the following were significant: an elevation in serum PSA levels at 45 Gy, detectable serum PSA immediately after prostatectomy, Gleason score 7--10, and serum PSA level >1 ng/ml before salvage radiotherapy.

CONCLUSION

Evaluation of serum PSA level at 45 Gy of salvage radiotherapy for biochemical relapses after prostatectomy may serve as a significant prognosticator for both biochemical and clinical disease-free outcomes.

Prostate-specific antigen after radiation therapy. Prognosis by pretreatment level and post-treatment nadir

After external beam radiation therapy, pretreatment prostate-specific antigen (PSA) is the most powerful predictor of outcome as measured PSA (biochemical) failure. The post-treatment nadir levels of PSA that predict best for subsequent freedom from PSA failure are debatable, and many nadir levels have been proposed as targets. Although lower nadirs generally are associated with superior outcomes, the identification of a single absolute nadir level was not selected at a recent ASTRO consensus conference. Rather, three consecutive PSA rises above the nadir, with date of failure at the midpoint between the nadir and first rise, were selected as a more useful end point for treatment failure.