Main Session
Sep
30
PQA 07 - Genitourinary Cancer, Patient Safety, Nursing/Supportive Care
3309 - Propensity Score Matched Analysis of External Beam Radiotherapy with or without Focal Boost to Intraprostatic Lesions in Prostate Cancer
Presenter(s)
Huseyin Cem Onal, MD - Baskent University Faculty of Medicine, Adana, Yuregir
H. C. Onal1,2, O. C. C. Guler2, G. Erbay3, B. Demirhan4, A. Elmali1, and M. N. Yavuz1; 1Baskent University Faculty of Medicine, Department of Radiation Oncology, Ankara, Turkey, 2Baskent University Faculty of Medicine, Adana Dr Turgut Noyan Research and Treatment Center, Department of Radiation Oncology, Adana, Turkey, 3Baskent University Faculty of Medicine, Adana Dr Turgut Noyan Research and Treatment Center, Department of Radiology, Adana, Turkey, 4Iskenderun Gelisim Hospital, Hatay, Turkey
Purpose/Objective(s):
The optimal radiotherapy strategy for localized prostate cancer remains under investigation. This study assessed the impact of external beam radiotherapy (EBRT) with a simultaneous integrated boost (SIB) to intraprostatic lesions on survival outcomes, recurrence patterns, and toxicity in intermediate- and high-risk prostate cancer patients. Key prognostic and predictive factors were also examined.Materials/Methods:
In this retrospective analysis, 712 intermediate- and high-risk prostate cancer patients treated with EBRT at 78 Gy—with or without a SIB (up to 86 Gy)—between 2010 and 2018 were evaluated. Propensity score matching (PSM) was applied to balance baseline characteristics. Endpoints included biochemical disease-free survival (bDFS), prostate cancer-specific survival (PCSS), local recurrence (LR), distant metastasis (DM), and treatment-related toxicities.Results:
After PSM, 417 patients were analyzed (208 with SIB and 209 without), comprising 38.6% intermediate-risk and 61.4% high-risk cases. Over a median follow-up of 8.6 years, the SIB group demonstrated significantly improved 8-year bDFS (93.8% vs. 83.5%; p = 0.006) and lower rates of DM (6.1% vs. 13.0%; p = 0.003) and LR (1.8% vs. 6.9%; p = 0.03). PCSS was comparable between groups (95.7% vs. 92.3%; p = 0.38). Multivariable analysis revealed that advanced T stage and the absence of SIB were associated with worse bDFS, DM, and LR, while a higher Gleason score predicted poorer PCSS and increased DM risk. Notably, there were no significant differences in 8-year Grade =2 genitourinary (10.1% vs. 10.5%; p = 0.98) or gastrointestinal toxicities (7.8% vs. 6.5%; p = 0.64) between the groups.Conclusion:
The addition of a simultaneous integrated boost to EBRT significantly enhances biochemical disease-free survival and reduces both local recurrence and distant metastases in intermediate- and high-risk prostate cancer patients, without increasing significant treatment-related toxicities. These results highlight the value of dose escalation via SIB in achieving improved local control and long-term outcomes while maintaining a favorable safety profile.