Multi-variable models of large International Prostate Symptom Score worsening at the end of therapy in prostate cancer radiotherapy

Purpose/objective Prospectively assessing clinical/dosimetry factors affecting the acute worsening of urinary functionality after radiotherapy for prostate cancer. Material/methods DUE01 population was considered, including patients treated with conventional or moderate hypo-fractionation (2.2-2.7 Gy/fr). Relevant clinical factors were collected, urinary symptoms were self-reported through the International Prostate Symptom Score (IPSS) before and at the end of radiotherapy; while absolute weekly dose-surface histograms (DSH_w) were chosen as dosimetry descriptors. An IPSS increase of at least 10 and 15 points (ΔIPSS ≥ 10 and ΔIPSS ≥ 15) were chosen as endpoints. Patients with baseline IPSS > 20 were excluded. Relevant factors were chosen through a bootstrap-based in silico methodology. Results Complete information was available for 380 patients: 77/380 (20%) and 28/380 (7%) with ΔIPSS ≥ 10 and ΔIPSS ≥ 15, respectively. Neoadjuvant hormone was protective (OR = 0.49 and 0.69). DSH_w at 8.5 Gy/week and 12 Gy/week were risk factors, with additional risk for patients who use cardiovascular drugs and anti-hypercholesterolemia drugs. In the hypo-fractionated subgroup (n = 209) the role of cardiovascular drugs (OR = 2.16) for ΔIPSS ≥ 10 and anti-hypercholesterolemia drugs (OR = 2.80) for ΔIPSS ≥ 15, together with DSH_w (10 Gy/week and 12.5 Gy/week, respectively), was confirmed. Conclusion Current study shows a dose-surface/volume effect for acute large worsening of urinary functionality; several clinical variables largely impact the risk and especially all the factors related with vascular diseases.