Patterns and predictors of amelioration of genitourinary toxicity after high-dose intensity-modulated radiation therapy for localized prostate cancer: implications for defining postradiotherapy urinary toxicity

Abstract

Background: Treatment-related toxicity and quality of life (QoL) considerations are important when counseling patients with localized prostate cancer (PCa).

Objective: To determine the incidence and longitudinal pattern of late genitourinary (GU) toxicity and QoL after high-dose, intensity-modulated radiotherapy (IMRT).

Design, setting, and participants: A total of 268 patients with localized PCa were treated between June 2004 and December 2008 at a tertiary referral center. Median follow-up was 5 yr (range: 3-7.7 yr).

Intervention: Patients underwent IMRT to a total dose of 86.4Gy; 50% of patients underwent neoadjuvant and concurrent androgen-deprivation therapy.

Outcome measurements and statistical analysis: Patients were evaluated with the prospectively obtained International Prostate Symptom Score (IPSS) questionnaire. GU toxicity was also scored using the Common Terminology Criteria for Adverse Events (CTCAE) v.4.0; toxicity events were defined as increase over baseline. Differences in increases in IPSS sums and QoL index between baseline IPSS sum and QoL index groups were analyzed using the Kruskal-Wallis and Mann-Whitney tests. Univariate and multivariate Cox regression models were applied.

Results and limitations: The overall median IPSS sum increase during follow-up was 3 and was less pronounced among patients with severe baseline symptoms compared with those with mild baseline symptoms (median increase: 0 vs 4; p<0.0001). Overall QoL index was unchanged after IMRT but appeared to improve in patients with dissatisfied baseline QoL compared with satisfied baseline QoL (p<0.0001). Fifty-five (20%) and 2 (1%) patients developed grade 2 and 3 late GU toxicities, respectively; however, in 28 of 57 patients (49%), toxicity resolved during follow-up. Even though the IPSS data were prospectively obtained, most patients were not treated within a prospective protocol.

Conclusions: Late GU toxicity after high-dose IMRT was mild; severe, late GU toxicity was rare. Changes in IPSS sum and QoL index were dependent on the baseline GU function, which might be useful for future patient counseling.

Keywords: Prostatic neoplasms; Radiotherapy; Toxicity; Urogenital abnormalities.