Validation of a nomogram to predict disease progression following salvage radiotherapy after radical prostatectomy: results from the SEARCH database

De-Escalation of Therapy for Prostate Cancer

Prostate cancer (PCa) is the second most commonly diagnosed cancer in men with around 1.4 million new cases every year. In patients with localized disease, management options include active surveillance (AS), radical prostatectomy (RP; with or without pelvic lymph node dissection), or radiotherapy to the prostate (with or without pelvic irradiation) with or without hormonotherapy. In advanced disease, treatment options include systemic treatment(s) and/or treatment to primary tumour and/or metastasis-directed therapies (MDTs). Specifically, in advanced stage, the current trend is earlier intensification of treatment such as dual or triple combination systemic treatments or adding treatment to primary and MDT to systemic treatment. However, earlier treatment intensification comes with the cost of increased morbidity and mortality resulting from drug-/treatment-related side effects. The main goal is and should be to provide the best possible care and oncologic outcomes with minimum possible side effects. This chapter will explore emerging possibilities to de-escalate treatment in PCa driven by enhanced insights into disease biology and the natural course of PCa such as AS in intermediate-risk disease or salvage versus adjuvant radiotherapy in post-RP patients. Considerations arising from advancements in PCa imaging and technological advancements in surgical and radiation therapy techniques including omitting pelvic lymph node dissection in the era of prostate-specific membrane antigen positron emitting tomography, the potential of MDT to delay/omit systemic treatment in metachronous oligorecurrence, and the efficacy of hypofractionation schemes compared with conventional fractionated radiotherapy will be discussed.

Can PSMA PET/CT help in dose-tailoring in post-prostatectomy radiotherapy?

There are few randomized trials to evaluate the use of PSMA-PET in the planning of post-prostatectomy radiotherapy. There are two unresolved questions 1) should we increase the dose to lesions visible on PSMA-PET 2) can we reduce dose in the case of a negative PSMA-PET. In this review, we summarize and discuss the available evidence in the literature. We found that in general, there seems to be an advantage for dose-increase, but ta large recent study from the pre-PSMA era didn't show an advantage for dose escalation. Retrospective studies have shown that conventional doses to PSMA-PET-positive lesions seem sufficient. On the other hand, in the case of a negative PSMA-PET, there is no evidence that dose-reduction is possible. In the future, the combination of PSMA-PET with genomic classifiers could help in better identify patients who might benefit from either dose- de-or -increase. We further need to identify intraindividual references to help identify lesions with higher aggressiveness.

Stereotactic Radiotherapy after Radical Prostatectomy in Patients with Prostate Cancer in the Adjuvant or Salvage Setting: A Systematic Review

Simple Summary

Stereotactic body radiotherapy, a type of high-precision radiotherapy delivering high doses within few treatment sessions has proven to be effective and well tolerated in prostate cancer patients treated with definite radiotherapy. This systematic review summarizes the available data and analyzes whether this modern treatment may routinely be offered to prostate cancer patients after radical prostatectomy.

Abstract

(1) Background: Prostate cancer is the most common cancer in men and can be treated with radical prostatectomy (RPE) or radiotherapy in the primary setting. Stereotactic radiotherapy (SBRT) has proven to be effective and well tolerated in this setting. However, if SBRT is an equally promising treatment option if applied in the adjuvant or salvage setting after RPE remains unknown. (2) Methods: We searched the PubMed and Embase databases with the following full-text queries in August 2021 for any combination of the terms “SBRT”, “prostate”, “adjuvant”, “postoperative”, “salvage”, “stereotactic radiotherapy”, “prostate bed”. There were no limitations regarding publication date or language. We adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations. (3) Results: We identified 11 individual studies that were included in this systematic review. Three publications included patients without prior radiotherapy and the remaining eight patients with prior radiotherapy. In all but two publications the radiation target was the macroscopic recurrence. SBRT was overall well tolerated with acceptable rates of acute and late gastrointestinal or genitourinary toxicity. Quality of life was published for two phase I trials with good results. There was a very heterogeneous reporting on biochemical control after SBRT. (4) Conclusions: At this point, ultra-hypofractionated RT using SBRT to the prostate bed remains experimental and its use should be restricted to clinical trials. Given the biological rationale for extreme hypofractionation in patients with prostate cancer and the acceptable toxicity rates that have been reported, further exploration of this field is warranted.

Predicting Cancer-Specific Survival Among Patients With Prostate Cancer After Radical Prostatectomy Based on the Competing Risk Model: Population-Based Study

Introduction: We aimed to develop an easy-to-use individual survival prognostication tool based on competing risk analyses to predict the risk of 5-year cancer-specific death after radical prostatectomy for patients with prostate cancer (PCa).

Methods: We obtained the data from the Surveillance, Epidemiology, and End Results (SEER) database (2004–2016). The main variables obtained included age at diagnosis, marital status, race, pathological extension, regional lymphonode status, prostate specific antigen level, pathological Gleason Score. In order to reveal the independent prognostic factors. The cumulative incidence function was used as the univariable competing risk analyses and The Fine and Gray's proportional subdistribution hazard approach was used as the multivariable competing risk analyses. With these factors, a nomogram and risk stratification based on the nomogram was established. Concordance index (C-index) and calibration curves were used for validation.

Results: A total of 95,812 patients were included and divided into training cohort (n = 67,072) and validation cohort (n = 28,740). Seven independent prognostic factors including age, race, marital status, pathological extension, regional lymphonode status, PSA level, and pathological GS were used to construct the nomogram. In the training cohort, the C-index was 0.828 (%95CI, 0.812–0.844), and the C-index was 0.838 (%95CI, 0.813–0.863) in the validation cohort. The results of the cumulative incidence function showed that the discrimination of risk stratification based on nomogram is better than that of the risk stratification system based on D'Amico risk stratification.

Conclusions: We successfully developed the first competing risk nomogram to predict the risk of cancer-specific death after surgery for patients with PCa. It has the potential to help clinicians improve post-operative management of patients.

Ten-Year Outcomes of Moderately Hypofractionated Salvage Postprostatectomy Radiation Therapy and External Validation of a Contemporary Multivariable Nomogram for Biochemical Failure

PURPOSE

Although high-level evidence supports moderately hypofractionated radiation therapy for definitive prostate treatment, there is less evidence for its use in the postprostatectomy setting. We externally validated a contemporary nomogram predicting biochemical failure (BF) after salvage radiation therapy (SRT) and report long-term disease control outcomes for hypofractionated SRT to the prostate bed.

METHODS AND MATERIALS

A retrospective review was performed for 112 patients treated with hypofractionated SRT (52.5 Gy in 20 fractions using 3-dimensional conformal radiation therapy) for pT2-4R0-1N0/XM0 prostate adenocarcinoma, with postoperative prostate-specific antigen (PSA) greater than 0.1 ng/mL or rising. Freedom from BF (FFBF), distant metastasis, cancer-specific mortality, and overall survival were analyzed from commencement of radiation therapy. Cox regression was performed on FFBF to account for covariates. BF was defined as a PSA ≥0.4 ng/mL and rising after SRT. Early SRT was defined as SRT commencing at a pre-SRT PSA of ≤0.2 ng/mL.

RESULTS

Median follow-up was 10.0 years (interquartile range, 9.3-10.7 years), median pre-SRT PSA was 0.4 ng/mL, and androgen deprivation therapy was used in 14% of patients. The 5/10-year FFBF, distant metastasis, cancer-specific mortality, and overall survival were 68%/51%, 7%/16%, 5%/11%, and 90%/75%, respectively. FFBF for early SRT compared with late SRT was 81% versus 66% at 5 years and 68% versus 49% at 10 years. On multivariable analysis, pre-SRT PSA, International Society of Urologic Pathology grade group, seminal vesicle invasion, and androgen deprivation therapy use were associated with FFBF. The nomogram c-index was 0.67, and it overestimated FFBF by 10% and 15% at 5 and 10 years, respectively, with confidence intervals overlapping the line of unity.

CONCLUSIONS

Hypofractionated SRT provides long-term disease control outcomes comparable to conventionally fractionated radiation therapy. Early SRT provides improved disease control, with two-thirds of patients with pre-SRT PSA of ≤0.2 ng/mL free of BF at 10 years. We performed the first external validation of the Tendulkar salvage nomogram, which showed a robust model performance.

Salvage radiotherapy for biochemical recurrence after radical prostatectomy: does the outcome depend on the prostate cancer characteristics?

OBJECTIVE

To build a model to evaluate the impact of salvage radiotherapy (SRT) in men with PSA rise or persistent PSA after undergoing radical prostatectomy (RP).

MATERIALS AND METHODS

The study included 107 node-negative patients treated with SRT after RP at a single institution. Patients received SRT for either prostate-specific antigen (PSA) rising, or PSA persistence after RP. All patients received local radiation to the prostate / seminal vesicle bed. The primary measured outcome was the biochemical recurrence (BCR) free survival. Multivariable Cox regression analysis was used to develop a risk-stratification group to identify predictive factors associated with the probability of BCR at 5yr.

RESULTS

At a median follow-up of 52 months, the BCR free survival rate and overall survival in 5 years was 73% and 94%, respectively. At multivariable analysis, pre-SRT PSA level > 0.35ng / mL (p = 0.023), negative margins (p = 0.038), and seminal vesicles invasion (p = 0.001) were significantly associated with BCR free survival. Three risk groups using regression analysis for SRT administration was built. Low-, intermediateand the high-risk groups had a BCR free survival in 5-years of 96%, 84%, and 44% (p = 0.0001), respectively.

CONCLUSIONS

We developed a risk group stratification to show the impact of SRT based on prostate cancer characteristics. SRT showed to be extremely beneficial for patients with low- and intermediate-risk tumors. Moreover, the risk-group built could identify patients classified as high-risk who might benefit from more aggressive treatment for SRT.

Nomograms are key decision-making tools in prostate cancer radiation therapy

BACKGROUND

The use of nomograms for predicting clinical endpoints has been well documented. Nomograms provide an individualized prognosis and help clinicians determine the effectiveness of treatment for a given patient. Early identification of potential treatment failure or toxicity allows alternative approaches to be considered, reducing unnecessary treatment, morbidity, and cost. This review aims to evaluate clinical potential of nomogram use for the management of prostate cancer radiotherapy patients.

METHODS

PubMed, Embase, and Scopus were searched for literature published between 2006 and 2016. The reported correlation between measured and nomogram-predicted probabilities of biochemical control, disease progression, survival and toxicity was reviewed, through an analysis of concordance indexes and areas under the curves.

RESULTS

Sixteen studies were reviewed. Outcomes predicted by the nomogram were very close to outcomes measured (concordance index of 0.7 and above) in the majority. But a combination of under and overestimation of outcome was also reported. The predictive accuracy of nomograms was very variable, however, most nomograms had accuracy greater than chance, indicated by a concordance index higher than 0.5.

CONCLUSION

Nomograms can be used as prognostic guides to aid clinical decision-making for prostate cancer patients until further research addresses the limitations presented in this review. Strict definitions of end points should be added to future models and perhaps models could be enhanced with the incorporation of genomic variables or tumor specific parameters.

Adjuvant and Salvage Radiotherapy after Radical Prostatectomy in Prostate Cancer Patients

CONTEXT

Prostate cancer (PCa) patients found to have adverse pathologic features following radical prostatectomy (RP) are less likely to be cured with surgery alone.

OBJECTIVE

To analyze the role of postoperative radiotherapy (RT) in patients with aggressive PCa.

EVIDENCE ACQUISITION

We performed a systematic literature review of the Medline and EMBASE databases. The search strategy included the terms radical prostatectomy, adjuvant radiotherapy, and salvage radiotherapy, alone or in combination. We limited our search to studies published between January 2009 and August 2016.

EVIDENCE SYNTHESIS

Three randomized trials demonstrated that immediate RT after RP reduces the risk of recurrence in patients with aggressive PCa. However, immediate postoperative RT is associated with an increased risk of acute and late side effects ranging from 15% to 35% and 2% to 8%, respectively. Retrospective studies support the oncologic efficacy of initial observation followed by salvage RT administered at the first sign of recurrence; however, the impact of this delay on long-term control remains uncertain. Hopefully, ongoing randomized trials will shed light on the role of adjuvant RT versus observation±salvage RT in individuals with adverse features at RP. Accurate patient selection based on clinical characteristics and molecular profile is crucial. Dose escalation, whole-pelvis RT, novel techniques, and the use of hormonal therapy might improve the outcomes of postoperative RT.

CONCLUSIONS

Immediate RT reduces the risk of recurrence after RP in patients with aggressive disease. However, this approach is associated with an increase in the incidence of short- and long-term side effects. Observation followed by salvage RT administered at the first sign of recurrence might be associated with durable cancer control, but prospective randomized comparison with adjuvant RT is still awaited. Dose escalation, refinements in the technique, and the concomitant use of hormonal therapies might improve outcomes of patients undergoing postoperative RT.

PATIENT SUMMARY

Postoperative radiotherapy has an impact on oncologic outcomes in patients with aggressive disease characteristics. Salvage radiotherapy administered at the first sign of recurrence might be associated with durable cancer control in selected patients but might compromise cure in others.

Change in Salvage Radiotherapy Management Based on Guidance With FACBC (Fluciclovine) PET/CT in Postprostatectomy Recurrent Prostate Cancer

PURPOSE

We explored the influence of FACBC (fluciclovine) PET/CT on the decision to offer radiotherapy and radiotherapy treatment field recommendations in postprostatectomy patients with recurrent prostate cancer.

PATIENTS AND METHODS

After obtaining institutional review board approval and informed consent, 87 patients with detectable prostate-specific antigen (PSA) levels were recruited into a prospective clinical trial. After an initial provider-determined radiotherapy plan based on conventional imaging, 44 of 87 patients were randomized to additionally undergo fluciclovine PET/CT. Pre- and post-fluciclovine radiotherapy decisions were compared and changes were noted. Statistical significance of these decision changes was determined.

RESULTS

Two of 44 patients in the experimental arm dropped out before fluciclovine scanning. Thirty-four (81.0%) of 42 had positive results on fluciclovine. Overall radiotherapy decision was changed in 17 (40.5%) of 42. Mean PSA, original Gleason score, and prostatectomy-PET interval did not differ significantly between patients with and without radiotherapy decision changes. Two (4.8%) of 42 had the decision for radiotherapy withdrawn due to positive extrapelvic findings. Radiotherapy field decision was changed in 15 (35.7%) of 42. Eleven (73.3%) of 15 had fields changed from prostate bed only to both prostate bed and pelvis, while 4 (26.7%) of 15 had fields changed from both prostate bed and pelvis to prostate bed only. Changes in overall radiotherapy decision and field were statistically significant (P < 0.0001). However, the change in the decision to offer radiotherapy or not was not statistically significant (P = 0.15).

CONCLUSIONS

Fluciclovine PET/CT significantly changed radiotherapy management decisions in postprostatectomy patients with recurrent prostate cancer. Further work in determining differences in PSA-free survival is ongoing.

An Examination of the Association between FOXA1 Staining Level and Biochemical Recurrence following Salvage Radiation Therapy for Recurrent Prostate Cancer

BACKGROUND

Standardly collected clinical and pathological patient information has demonstrated only moderate ability to predict risk of biochemical recurrence (BCR) of prostate cancer in men undergoing salvage radiation therapy (SRT) for a rising PSA after radical prostatectomy (RP). Although elevated FOXA1 staining has been associated with poor patient outcomes following RP, it has not been studied in the specific setting of SRT after RP. The aim of this study was to evaluate the association between FOXA1 staining level and BCR after SRT for recurrent prostate cancer.

METHODS

A total of 141 men who underwent SRT at our institution were included. FOXA1 staining levels in primary tumor samples were detected using immunohistochemistry. FOXA1 staining percentage and intensity were measured and multiplied together to obtain a FOXA1 H-score (range 0-12) which was our primary staining measure. P-values ≤ 0.0056 were considered as statistically significant after applying a Bonferroni correction for multiple comparisons.

RESULTS

There was not a significant association between FOXA1 H-score and risk of BCR when considering H-score as an ordinal variable or as a categorical variable (all P ≥ 0.090). Similarly, no significant associations with BCR were observed for FOXA1 staining percentage or staining intensity (all P ≥ 0.14).

CONCLUSIONS

FOXA1 staining level does not appear to have a major impact on risk of BCR after SRT.

Continuous prostate-specific antigen rise despite salvage radiotherapy following radical prostatectomy: Pattern of clinical relapse and predictive factors

Salvage radiotherapy for post-prostatectomy biochemical recurrence does not always control the disease. It would be useful to identify patients who would not benefit from radiotherapy to the prostate bed prior to making treatment recommendations. One such group of patients is those who experience continuously rising prostate-specific antigen (PSA) despite radiotherapy. The purpose of this study was to identify risk factors for continuous PSA increase and the pattern of radiological relapse during follow-up. We performed a retrospective comparison of two patient groups with PSA decline or continuous increase following salvage radiotherapy to the prostate bed. All patients received 3-D conformal radiotherapy (35 fractions of 2 Gy). Patients with continuous PSA increase were more likely to have had complete surgical resection (negative margins) and a shorter interval to radiotherapy (<24 months). However, the only statistically significant risk factor was Gleason score. Sixty-four percent of patients with a Gleason score of 9 developed continuously increasing PSA, indicating that residual subclinical cancer was not located in the prostate bed. The median time to radiological recurrence was 43 months. Isolated pelvic nodal recurrence was uncommon. Almost all patients with radiological recurrence had high-risk disease, in particular stage pT3. In conclusion, the majority of patients with biologically aggressive tumors with Gleason score 9 were not adequately treated with prostate bed radiotherapy alone. The predominant pattern of radiological recurrence was outside of the pelvis. Therefore, the problem of distant micrometastases has to be addressed.

Proposed prognostic scoring system evaluating risk factors for biochemical recurrence of prostate cancer after salvage radiation therapy

OBJECTIVE

To update a previously proposed prognostic scoring system that predicts risk of biochemical recurrence (BCR) after salvage radiation therapy (SRT) for recurrent prostate cancer when using additional patients and a PSA value of 0.2 ng/mL and rising as the definition of BCR.

PATIENTS AND METHODS

We included 577 patients who received SRT for a rising PSA after radical prostatectomy in this retrospective cohort study. Clinical, pathological, and SRT characteristics were evaluated for association with BCR using relative risks (RRs) from multivariable Cox regression models.

RESULTS

With a median follow-up of 5.5 years after SRT, 354 patients (61%) experienced BCR. At 5 years after SRT, 40% of patients were free of BCR. Independent associations with BCR were identified for the PSA level before SRT (RR [doubling]: 1.25, P < 0.001), pathological tumour stage (RR [T3a vs T2] 1.21, P = 0.19; RR [T3b/T4 vs T2] 2.09, P < 0.001; overall P < 0.001), Gleason score (RR [7 vs <7] 1.63, P < 0.001; RR [8-10 vs <7] 2.28, P < 0.001; overall P < 0.001), and surgical margin status (RR [positive vs negative] 0.71, P = 0.003). We combined these four variables to create a prognostic scoring system that predicted BCR risk with a c-index of 0.66. Scores ranged from 0 to 7, and 5-year freedom from BCR for different levels of the score was as follows: Score = 0-1: 66%, Score = 2: 46%, Score = 3: 28%, Score = 4: 19%, and Score = 5-7: 15%.

CONCLUSION

We developed a scoring system that provides an estimation of the risk of BCR after SRT. These findings will be useful for patients and physicians in decision making for radiation therapy in the salvage setting.

Radiotherapy in the management of prostate cancer after radical prostatectomy

The choice of treatment options for prostate cancer patients who have undergone radical prostatectomy depends on their risk profile, which is determined by the tumor node metastasis (TNM) status, histopathologic findings, and the pre- and post-radical prostatectomy PSA characteristics. The results of large clinical studies with a 10-year follow-up or more are the backbone of predictive models for risk estimates that incorporate these criteria and also for guideline recommendations. For low-to-intermediate-risk prostate cancer patients and older patients, observation with--in case of biochemical recurrence--early salvage radiotherapy can be advised after R0 resection, thus, avoiding overtreatment. After R1 resection, adjuvant radiotherapy should be considered. Patients with two or more positive lymph nodes and/or with distant metastasis may benefit from adjuvant hormone deprivation therapy. Beyond this rough outline, detailed analysis of subgroups is still required (and ongoing) to enable individually optimized treatment.

Salvage radiotherapy after robot-assisted laparoscopic radical prostatectomy

OBJECTIVE

To assess the incidence and efficacy of salvage radiotherapy (SRT) after robot-assisted radical prostatectomy (RARP). RARP has been linked to an increased use of adjuvant treatments. If RARP would result in an increased local recurrence rate, response rates to SRT could be expected to be better after RARP than after more conventional methods of prostatectomy. The incidence and efficacy of SRT in a RARP population were compared with nomogram prediction.

METHODS

Patient data were prospectively registered. Biochemical recurrence (BCR) was defined as a prostate-specific antigen (PSA) ≥0.1 ng/mL. SRT was offered to men with BCR after RARP. The Stephenson nomogram predictions were compared with outcome after SRT.

RESULTS

Of 1087 men, 157 (14.4%) received SRT for BCR or persistent PSA levels during a median follow-up of 1078 days after RARP. Median PSA level before SRT was 0.2 ng/mL. Three-year BCR-free rate was 64% for men after SRT. pN (pNx, pN0, pN1) and PSA level before SRT were independent predictors of the BCR interval after SRT. Men with more extensive fascia preservation were more likely to respond favorably to SRT. The Stephenson nomogram prediction showed a concordance rate of 0.66 in this RARP population. Limitations of the study are the retrospective design and limited follow-up duration.

CONCLUSION

In our RARP series, the use and efficacy of SRT were comparable with open prostatectomy series. The Stephenson nomogram reliably predicted outcome in patients with RARP with SRT, suggesting that similar characteristics predict response to SRT after RARP compared with open prostatectomy.

Radical prostatectomy: value of prostate MRI in surgical planning

The introduction of serum prostate-specific antigen to the prostate cancer screening algorithm has led to an increase in prostate cancer diagnosis as well as a migration toward lower-stage cancer at the time of diagnosis. This stage migration has coincided with changes in treatment options; these include active surveillance, new therapies, and advances in surgical techniques. Use of robot-assisted radical prostatectomy (RARP) as a surgical technique has seen a significant increase over the past several years: the number of patients undergoing RARP has risen from 1% to 40% of all prostatectomies from 2001-2006 to as many as 80% in 2010. The robotic interface provides a 3D magnified view of the surgical field, intuitive instrument manipulation, motion scaling, tremor filtration, and excellent dexterity and range of motion. However, in some cases, the lack of tactile (haptic) feedback may limit the surgeon's decision making ability in assessing malignant involvement of the neurovascular bundles. Pre-operative planning relies on nomograms based on limited clinical and prostate biopsy information. The surgical decision to spare or resect the neurovascular bundles is based on clinical information which is not spatially or anatomically based. Advances in magnetic resonance imaging (MRI) may provide spatially localized information to fill this void and aid surgical planning, particularly for robotic surgeons. In this review, we discuss the potential role of pre-operative MRI in surgical planning for radical prostatectomy.

The need for, and utilization of prostate-bed radiotherapy after radical prostatectomy for patients with prostate cancer in British Columbia

INTRODUCTION

Three randomized trials have demonstrated that post-radical prostatectomy (RP) radiotherapy decreases biochemical relapse for those with adverse pathology. Our purpose was to describe the incidence of pathologic risk factors for recurrence in a contemporary series of patients treated with RP and to describe the use of post-RP radiotherapy.

METHODS

All incident prostate cancers diagnosed between January 2005 and December 2007 were identified from the tumour registry. Cases were then linked to radiotherapy records which included dose and modality (external beam radiotherapy and brachytherapy). The pathology reports in the tumour registry were reviewed for pathologic stage, grade and margin status.

RESULTS

We identified 9223 patients with prostate cancer. Overall, 36.3% of patients treated with RP had positive margins, and may have benefited from adjuvant radiotherapy. After RP, 332 (15%) patients had radiotherapy to the prostate bed; of these, only 25 (1.1%) received truly adjuvant radiotherapy (delivered within 6 months with a prostate-specific antigen of <0.2 ng/mL). Of the 2181 patients treated with RP, 270 (12%) were seen by a radiation oncologist within 6 months of RP. Of the 1015 patients (47%) with adverse RP pathology (positive margins, extracapsular extension or seminal vesicle invasion), 230 (23%) were seen by a radiation oncologist within 6 months of RP.

CONCLUSION

Not all patients with adverse prostatectomy pathology were seen by a radiation oncologist post-prostatectomy, and very few received adjuvant radiotherapy despite almost half of them having risk factors for relapse.

Does salvage radiation therapy change the biology of recurrent prostate cancer based on PSA doubling times? Results from the SEARCH database

OBJECTIVE

To investigate whether salvage radiation therapy (SRT) may promote prostate cancer (PCa) transformation to more aggressive phenotypes. To accomplish that, we identified men who underwent SRT after radical prostatectomy for PCa and failed SRT. PSA doubling time (PSADT) was used as a surrogate endpoint for cancer aggressiveness. We compared PSADT calculated before start of SRT and after SRT failure.

METHODS

Of 287 men in the SEARCH database since 1988 who underwent SRT, we detected 78 with SRT failure defined as PSA ≥ 0.2 ng/mL above the post-SRT nadir. Of these, 39 had PSADT available before and after SRT, which was compared using Wilcoxon's paired test with men serving as their own controls. We tested predictors of PSADT change using multivariable logistic regression.

RESULTS

There were no differences in PSADT before and after SRT (10.2 vs 12.6 months; P = .46). However, in some individual cases, large changes were observed. Only seminal vesicle invasion showed a trend towards an association with a shorter post-SRT PSADT relative to the pre-SRT PSADT (P = .13).

CONCLUSION

Overall, the PSADT after and before SRT were statistically identical, suggesting that after SRT failure, PCa does not emerge with more aggressive biological features. Further studies are needed to identify predictors and the clinical relevance of individual PSADT changes noted in our study.

Can early implementation of salvage radiotherapy for prostate cancer improve the therapeutic ratio? A systematic review and regression meta-analysis with radiobiological modelling

PURPOSE

For prostate cancer that is thought to be locally recurrent after prostatectomy, the optimal timing, dose and techniques for salvage radiotherapy (SRT) have not been established. Here we perform a systematic review of published reports including regression meta-analysis and radiobiologic modelling to identify predictors of biochemical disease control and late toxicity.

METHODS

We performed a review of published series reporting treatment outcomes following SRT. Studies with at least 30 patients, median PSA before SRT of less than 2.0 ng/mL, and median follow-up of greater than 36 months were identified. Univariate and multivariate analyses were performed to test Gleason Score, SRT dose, SRT timing, pre-SRT PSA, whole pelvic irradiation and androgen deprivation therapy as predictors of 5-year biochemical progression-free survival (bPFS) and severe (grade≥3) late GI and GU toxicity. bPFS and toxicity data were fit to tumour control probability and normal tissue complication probability models, respectively.

RESULTS

Twenty-five articles met the inclusion criteria for this analysis. Five-year bPFS ranged from 25% to 70%. Severe late GI toxicity rates were 0% to 9%, and severe late GU toxicity rates were 1-11%. On multivariate analysis, bPFS increased with SRT dose by 2.5% per Gy and decreased with pre-SRT PSA by 18.3% per ng/mL (p<0.001). Late GI and GU toxicity increased with SRT dose by 1.2% per Gy (p=0.012) and 0.7% per Gy (p=0.010), respectively. Radiobiological models demonstrate the interaction between pre-SRT PSA, SRT dose and bPFS. For example, an increase in pre-SRT PSA from 0.4 to 1.0 ng/mL increases the SRT dose required to achieve a 50% bPFS rate from 60 to 70Gy. This could increase the rate of severe late toxicity by approximately 10%.

CONCLUSION

Biochemical control rates following SRT increase with SRT dose and decrease with pre-SRT PSA. Severe late GI and GU toxicity rates also increase with SRT dose. Radiobiological models suggest that the therapeutic ratio of SRT may be improved by initiating treatment at low PSA levels.

Treatment of men with rising prostate-specific antigen levels following radical prostatectomy

Approximately one-third of patients who undergo radical prostatectomy for prostate cancer will develop a detectable prostate-specific antigen (PSA) level within 10 years. Biochemical recurrence of disease is defined as a rising PSA level in the absence of clinical or radiographic evidence of disease. Management of PSA recurrence is controversial, as prostate cancer may take an indolent course, or it may aggressively develop into metastatic disease. The only potentially curative treatment for biochemical failure after prostatectomy is salvage radiotherapy. Noncurative treatment options include hormone therapy or clinical trials of a novel systemic agent. This article will address management options for a rising PSA level after prostatectomy, as well as ongoing studies exploring molecular biomarkers as prognostic tumor markers and potential targets for prostate cancer therapy.

Association of cigarette smoking with interval to biochemical recurrence after radical prostatectomy: results from the SEARCH database

OBJECTIVES

To analyze the association between cigarette smoking and biochemical recurrence (BCR) after radical prostatectomy among men from the Shared Equal Access Regional Cancer Hospital (SEARCH) cohort.

METHODS

We performed a retrospective analysis of 1267 subjects from the SEARCH cohort treated from 1998 to 2008 with smoking status available from the preoperative notes. A comparison of the baseline patient and disease characteristics between the current smokers and nonsmokers (past and never smokers combined) was performed using the chi-square and rank sum tests. The univariate and multivariate associations between smoking status and BCR-free survival were analyzed using Kaplan-Meier plots, the log-rank test, and Cox proportional hazard models.

RESULTS

Of the 1267 patients, 408 (32%) were active smokers and 859 (68%) were nonsmokers at surgery. The current smokers were younger (P < .001), more likely to be black (P < .001), and had a lower body mass index (P < .001), a greater percentage of positive biopsy cores (P = .039), a greater preoperative prostate-specific antigen level (P = .003), more extracapsular extension (P = .003) and seminal vesicle invasion (P = .029), and lower prostate volumes (P = .002). On univariate analysis, smokers had a risk of BCR similar to that of nonsmokers (hazard ratio 1.19, P = .129). On multivariate analysis, smoking was associated with an increased risk of BCR when adjusted for body mass index only (hazard ratio 1.37, P = .008). However, after adjustment for multiple preoperative characteristics, the association was attenuated and no longer statistically significant (hazard ratio 1.12, P = .325). After additional adjustment for postoperative features, such as tumor grade and stage, smoking was unrelated to the risk of BCR (hazard ratio 0.91, P = .502).

CONCLUSIONS

Among patients undergoing radical prostatectomy in the SEARCH cohort, cigarette smoking was associated with slightly more advanced disease but a similar risk of BCR.

Salvage radiotherapy for patients with PSA relapse following radical prostatectomy: issues and challenges

A progressively rising level of serum prostate specific antigen (PSA) after radical prostatectomy (RP) invariably indicates the recurrence of prostate cancer. The optimal management of patients with post-RP PSA relapse has remained uncertain due to a wide variability in the natural course of post-RP PSA relapse and the inability to separate a recurrent disease confined to the prostate bed from that with occult distant metastasis. Management uncertainty is further compounded by the lack of phase III clinical studies demonstrating which therapeutic approach, if any, would prolong life with no significant morbidity. Radiotherapy has been the main therapeutic modality with a curative potential for patients with post-RP PSA relapse. This review article depicts issues and challenges in the management of patients with post-RP PSA relapse, presents the literature data for the efficacy of salvage radiotherapy, either alone or in combination of androgen ablation therapy, and discusses future directions that can optimize treatment strategies.