First application of a pixel-wise analysis on bladder dose–surface maps in prostate cancer radiotherapy. Issue 1 (April 2016)

• Record Type: Journal Article
• Authors: Palorini, Federica; Cozzarini, Cesare; Gianolini, Stefano; Botti, Andrea; Carillo, Viviana; Iotti, Cinzia; Rancati, Tiziana; Valdagni, Riccardo; Fiorino, Claudio
• Is Part Of: Radiotherapy and oncology. Volume 119:Issue 1(2016:Apr.)
• Page Start: 123
• Page End: 128
• Publication Date: 2016-04
• Subjects: Radiotherapy -- Prostate cancer -- Urinary toxicity -- Dose–volume effects; Oncology -- Periodicals; Radiotherapy -- Periodicals; Tumors -- Periodicals; Medical Oncology -- Periodicals; Neoplasms -- radiotherapy -- Periodicals; Radiotherapy -- Periodicals; Radiothérapie -- Périodiques; Cancérologie -- Périodiques; Tumeurs -- Périodiques; Electronic journals; 616.9940642
• DOI: 10.1016/j.radonc.2016.02.025
• Languages: English
• ISSNs: 0167-8140

Abstract

Abstract: Purpose: To develop a method for investigating local dose effects on the bladder after prostate cancer radiotherapy based on dose–surface maps (DSMs). Background and purpose: DSMs of patients included in a prospective study (DUE01) were generated by virtually cutting bladder contours at the points intersecting the sagittal plane passing through its center-of-mass: maps were laterally normalized and aligned at the posterior inferior point. The average DSMs of patients with/without toxicity, the DSMs of differences and t statistic were used to select regions better discriminating patients with toxicity. A total of 72 patients with no/mild urinary symptoms before radiotherapy and who were treated with moderate hypo-fractionation (2.5–2.65 Gy/fr, 70–74 Gy) were considered, and the endpoint was an International Prostate Symptoms Score (IPSS)⩾15 at the end of therapy (IPSSend ⩾ 15, n = 25/72). Results: The DSMs of patients with/without toxicity were significantly different ( p < 0.05). The percentage of bladder circumference receiving >50–70 Gy at 5–7 mm from the base was associated with an IPSSend ⩾ 15 (odds ratios: 1.03–1.07). Different patterns were recognized for specific symptoms. With frequency/urgency, a quasi-threshold effect on the absolute posterior dose at 5–12 mm from the base (2 Gy equivalent doses = 80–82 Gy, α / β = 3–5 Gy) was observed. Conclusions: Local-dose effects for acute symptoms were detected in a group of patients treated within a moderately hypo-fractionated protocol. The results for frequency/urgency were consistent with a threshold effect on the trigone.