ESTRO 2023

Session Item

Sunday

May 14

16:45 - 17:45

Strauss 2

Urology

Chair: Ann Henry, United Kingdom;

Co-Chair: Marcin Miszczyk, Poland

Session Code: 2550

Session Type: Proffered Papers

Track: Brachytherapy

17:05 - 17:15

Prospective study of MRI guided HDR-BT and EBRT: 10years experience of a mono-institutional cohort

Alfonso Gómez-Iturriaga, Spain

Presentation Number: OC-0627

Abstract

Abstract Title:

Prospective study of MRI guided HDR-BT and EBRT: 10years experience of a mono-institutional cohort

Authors:

Alfonso Gomez Iturriaga¹, Itziar Valverde-Pascual², Fernando Perez Azorin³, Borja Santos-Zorrozua⁴, Jose Antonio Guerrero⁵, Felipe Couñago⁶, Jon Cacicedo⁷, Marina Marban⁷, Iñigo San Miguel⁸, Iratxe Raton⁷, Carlos Mascarell⁷, David Büchser⁷

¹Hospital Universitario Cruces, Biocruces Bizkaia Health Research Institute, Radiation Oncology, Barakaldo, Spain; ²Hospital Universitario Cruces, Biocruces Bizkaia Health Research Institute, Radiation Physics, Barakaldo , Spain; ³Hospital Universitario Cruces, Biocruces Bizkaia Health Research Institute, Radiation Physics, Barakaldo, Spain; ⁴Biocruces Bizkaia Health Research Institute, Cruces University Hospital,, Scientific Coordination Unit, Barakaldo, Spain; ⁵UPV/EHU, Surgery, Barakaldo, Spain; ⁶Genesis Care, San Francisco de Asis and La Milagrosa, Radiation Oncology, Madrid, Spain; ⁷Biocruces Bizkaia Health Research Institute, Radiation Oncology , Barakaldo , Spain; ⁸Biocruces Bizkaia Health Research Institute, Radiation Oncology, Barakaldo , Spain

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Purpose or Objective

To evaluate the predictive factors for biochemical failure and distant metastases in a prospective cohort of patients with localized prostate cancer treated with the combination of HDR brachytherapy and External Beam Radiotherapy. Second, to analyze the biochemical failure-free (BFFS) and metastases-free survival (MFS) rates at 5 and 7 years of follow-up of patients stratified by risk groups.

Material and Methods

Patients with histological confirmation of intermediate (IR) or high-risk (HR)prostate adenocarcinoma were analyzed. Patients without staging MRI and those with pelvic lymph node involvement were excluded from this analysis. The treatment administered consisted of a single fraction of HDR of 15 Gy combined with RT of 37.5 Gy in 15 fractions. Patients with unfavorable IR disease received ADT for 6 mo and patients with HR 24 mo of ADT. Descriptive analyses were performed. Univariate and multivariate Hazard Ratios were obtained from Cox proportional regression models. Finally, the Kaplan-Meier model was used to describe the survival of the events of interest.

Results

309 patients were treated prospectively (199 were IR and 110 HR). Median age was 72 years (IQR 68 – 75); 58.3% were MRI stage ≤ T2c, 34.1% T3a and 7.6% T3b; ISUP grade was 1-3 in 78.9% and ISUP 4-5 in 21.1%. 71.8% of patients had ≤ 50% positive cores in biopsy and 28.2% had >50%. Median pre-treatment PSA was 9.9 ng/mL.
After a median follow-up of 77.8 months (IQR 24.9 – 107.1 months), 41 patients presented a biochemical failure and 17 developed distant metastases.
Multivariate cox-regression analyses found that MR-T3b Stage was the only predictive factor (HR 3.88, 95% CI 1.68-8.94, p=0.001) for biochemical failure and the number of positive cores (>50%) the only independent predictive factor of distant metastases (HR 4.36, 95% 1.72-11-1, p= 0.002)
In terms of survival, the BFFS rates at 5 and 7 years were 92.5% and 88.1% for patients with intermediate disease and 84.7% and 78.1 for patients with high-risk.
MFS rates were 97.3% and 95.1% for intermediate-risk and 88.6% and 83.3% for high-risk disease.

Conclusion

Combined treatment of HDR BT with EBRT achieves excellent biochemical and metastatic control rates. Patients with multiparametric MRI evidence of invasion of the seminal vesicles and involvement of more than 50% of the cores in the prostate biopsy are patients with a higher risk of presenting a biochemical recurrence or developing metastases due to their prostate cancer.