Abstract
Purpose: To assess the survival outcomes of patients with metastatic prostate cancer (mPCa) who undergo greater cytoreductive radiotherapy in a real-world clinical practice and determine their prognostic factors.Methods: We performed a retrospective study of 160 patients with mPCa who underwent cytoreductive radiotherapy between 2009 and 2018 at a single institution. The degree of the cytoreductive burden was calculated for each patient. Overall survival (OS) was calculated from the date of detection of metastases. Variables associated with prostate-specific antigen (PSA) response and OS were evaluated via univariate and multivariate analyses.Results: The median follow-up period was 47.2 months. The median OS was 42.3 months with a 5-year OS rate of 37.9%. The PSA levels of 90 patients (56.7%) decline by > 50% after radiotherapy. The 5-year OS rates of patients who underwent total, major, and minor cytoreductive radiotherapy were 53.4, 38.2, 17.6%, respectively; the corresponding median OS intervals were 62.5, 41.0, and 24.4 months, respectively (P < 0.001). A greater extent of cytoreduction (P < 0.05), lower PSA at radiotherapy initiation [hazard ratio 0.51, 95% confidence interval [CI] 0.33–0.78; P = 0.002] and better PSA response [hazard ratio 0.47, 95% CI 0.30–0.72; P < 0.001] were independent factors associated with superior OS. A high metastatic burden (as defined in the CHAARTED trial) was the only independent predictor of a poorer PSA response (odds ratio 0.36, 95% CI 0.19–0.69; P = 0.002). Grade 2 late gastrointestinal and genitourinary toxicities were observed in 3 and 2 patients, respectively, and only 1 patient had grade 3 late gastrointestinal toxicity.Conclusion: Cytoreductive radiotherapy is effective and safe in select patients with mPCa. Greater cytoreduction, together with lower PSA at radiotherapy initiation and improved PSA response are favorable prognostic factors. Further studies are needed to confirm our findings.
Highlights
Systemic therapy alone is currently the standard management approach for metastatic prostate cancer ([m]PCa)
In several other metastatic and recurrent cancers, the percentage of treated tumor burdens (TBs) was found to be associated with improved outcome [6,7,8]; the association between the extent of cytoreduction and any clinical benefit in patients with mPCa has not been identified, and little is known about the effect of greater cytoreductive radiotherapy on the outcomes of patients with mPCa except for a recent respective study with a small sample size which reported that combined primary-directed radiotherapy (PDRT) and metastasis-directed radiotherapy (MDRT) delayed disease progression than PDRT alone in the oligometastatic setting [9]
This study, which was based on real-world data from our institution, revealed superior treatment responses and survival outcomes in select patients with mPCa, and identified valuable prognostic factors for those who receive cytoreductive radiotherapy combined with systematic therapy
Summary
Systemic therapy alone is currently the standard management approach for metastatic prostate cancer ([m]PCa). Stereotactic ablative radiotherapy (SABR) was reported to be associated with an improved OS in patients with oligometastatic cancers, including oligometastatic PCa [5]. In several other metastatic and recurrent cancers, the percentage of treated tumor burdens (TBs) was found to be associated with improved outcome [6,7,8]; the association between the extent of cytoreduction and any clinical benefit in patients with mPCa has not been identified, and little is known about the effect of greater cytoreductive radiotherapy on the outcomes of patients with mPCa except for a recent respective study with a small sample size which reported that combined PDRT and MDRT delayed disease progression than PDRT alone in the oligometastatic setting [9]. Our present study aimed at assessing the survival outcomes and identifying prognostic factors when applying cytoreductive radiotherapy to patients with mPCa in a real-world clinical setting
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