Session Item

To evaluate treatment outcomes and toxicity of the moderately hypofractionated schedule with the total dose of 52.8 Gy in 16 daily fractions delivered with IMRT/VMAT. The treatment schedule selection was motivated by limited technology resources.

One hundred consecutive M0 patients with post-prostatectomy radiotherapy were evaluated based on intention to treat. Median age was 64 years. Radiotherapy indication was adjuvant in 19%, early salvage in 46% and salvage (PSA >0,5 ng/ml) in 35%. Clinical target volume was limited to the prostate bed (PB) in 89% and in 11% pelvic nodes irradiation was included. The dose prescription for PTV_PB was 52.8 Gy in 16 fractions of 3.3 Gy and 40 Gy in 16 fractions of 2.5 Gy for PTV_pelvis and treatment was delivered daily by image-guided step-and-shoot IMRT or VMAT. No androgen deprivation treatment (ADT) was administered in 42%, short-term LHRHa in 30%, 2-years bicalutamide in 12% and long-term LHRHa in 16%. Patients were followed with PSA every 3 to 6 months. If indicated, conventional imaging was used before radiotherapy and at PSA progression. The Common Terminology Criteria v.4 for Adverse Events scale was used for toxicity evaluation.

The median follow-up was 61 months. Five-year freedom from biochemical failure (FFBF) was 79.7%, distant metastases-free survival was 93.8% and overall survival was 98.8%.  The multivariate analysis showed the treatment indication was the only significant factor for 5-year FFBF which was 86.3% vs. 67.6% for adjuvant and early salvage vs. salvage radiotherapy respectively (HR 0.15, 95% CI 0.05 – 0.47, p = 0.001). Acute GI toxicity grade 2 was recorded in 24% (mostly rectal mucositis and rectal pain), grade G3 in 2% (one small intestine obstruction after completion of adjuvant radiotherapy and one diarrhea) and acute GU toxicity grade 2 in v 10% (mostly cystitis and urinary frequency) and no grade 3. Cumulative rate of late GI toxicity grade ≥2 was observed in 9% (rectal hemorrhage and fecal incontinence) and late GU toxicity grade ≥2 in 16% (urinary retention, urinary frequency, and progression of urinary incontinence). Metachronous malignancies were recorded in 6% (2 NMIBC, 2 colon cancers, 1 lung cancer and 1 pancreatic cancer).

Observed results confirmed efficacy and safety of post-prostatectomy hypofractionated radiotherapy in 16 daily fractions. Adjuvant and early salvage radiotherapy indication was an independent predictor of favorable long-term biochemical control.