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Impact of Salvage Radiotherapy Initiation at PSA ≤0.5 ng/mL on Survival Outcomes in Patients With Relapsed Prostate Cancer After Prostatectomy
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The optimal timing to initiate salvage radiation therapy after prostatectomy is unclear. This study evaluated the outcomes of salvage radiation therapy initiated at a PSA level ≤0.5 ng/mL in patients with biochemically recurrent prostate cancer. The study included 397 patients, with 45.8% of the patients receiving treatment when their pre–radiation therapy PSA levels were ≤0.5 ng/mL. They found that pre–radiation therapy PSA level was the most significant predictor of biochemical recurrence–free survival and metastasis-free survival outcomes. In addition to PSA levels, seminal vesicle invasion was predictive of metastatic disease.
- This study involving patients with biochemical recurrence of prostate cancer following radical prostatectomy found that early initiation of salvage radiotherapy at a PSA level ≤0.5 ng/mL was predictive of better oncologic outcomes.
abstract
This abstract is available on the publisher's site.
Access this abstract nowBACKGROUND AND PURPOSE
Salvage radiation therapy (SRT) is indicated for biochemical failure after radical prostatectomy. Prior data have shown that initiation of SRT at lower PSA levels improves subsequent biochemical control, yet given the long natural history of prostate cancer questions remain regarding optimal timing of SRT. We analyzed the impact of prostate specific antigen (PSA) level at time of salvage radiotherapy with regard to both biochemical relapse-free (bRFS) as well as metastasis-free survival (MFS) in patients with biochemically recurrent prostate cancer.
METHODS
Using prospective institutional tumor registry data, univariate and multivariable-adjusted Cox proportional hazards models were constructed to assess association between outcomes and clinical and pathologic prognostic features, including pre-SRT PSA, interval from prostatectomy to SRT, androgen deprivation therapy (ADT), and adverse pathologic features.
RESULTS
We identified 397 patients who received salvage RT between 1985 and 2016: 187 (45.8%) received SRT initiated when pre-RT PSA was ≤0.5 ng/ml; 212 (52.0%) patients had pre-SRT PSA > 0.5 ng/ml. Independent of pathologic risk status and ADT use, pre-SRT PSA ≤ 0.5 ng/ml was the most significant predictor of bRFS (HR 0.39, 95% CI [0.27, 0.56]) as well as MFS (HR = 0.58, 95% CI [0.37, 0.91]). Seminal vesicle invasion was also associated with shorter interval to biochemical failure, HR = 1.79, 95% CI [1.07, 2.98], and eventual metastases, HR = 2.07, 95% CI [1.14, 3.740].
CONCLUSIONS
Initiation of salvage RT while PSA levels remain ≤0.5 ng/ml was associated with improved MFS. Consideration for salvage RT initiation while PSA levels remain low is warranted to minimize risk of future prostate cancer metastasis.
Additional Info
Disclosure statements are available on the authors' profiles:
The impact of salvage radiotherapy initiation at PSA ≤ 0.5 ng/ml on metastasis-free survival in patients with relapsed prostate cancer following prostatectomy
Prostate 2022 Oct 31;[EPub Ahead of Print], EE Lee, T Singh, C Hu, M Han, CJ Deville, A Halthore, S Greco, P Tran, T DeWeese, DY SongFrom MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
The authors address whether salvage radiation therapy (sRT) delivered at a PSA level of 0.5 ng/ml or less was associated with a prolongation in metastasis free survival (MFS). They also address the same question using a PSA cut point of 0.2 ng/ml. The authors found that there was a significant association with a prolongation in MFS when sRT was initiated at a PSA level of 0.5 ng/ml or less, but not 0.2 ng/ml or less. A prior study1 that compiled individual patient data from several academic institutions found that adjuvant as compared to early sRT (median PSA 0.3 ng/ml) was associated with a significant decrease in all-cause mortality risk (Adjusted Hazard Ratio: 0.33) in men with two high-risk factors (prostatectomy Gleason score 8, 9 or 10 AND prostatectomy T-category 3 or 4). Therefore, it is possible if the authors of the current study examined the subset of men who had both of these high-risk factors that they may find that initiating sRT by a PSA level of 0.2 ng/ml or less versus higher is also associated with a prolongation in MFS. Therefore, stratifying men by the number of high-risk factors found at radical prostatectomy when examining whether an association exists between the time-dependent use of sRT by a given PSA level and long-term cancer control endpoints such as MFS may be important for clarifying the appropriate use and timing of sRT.
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