ESTRO 2023 - Abstract Book

S452

Sunday 14 May 2023

ESTRO 2023

We have developed and internally validated a clinically plausible Bayesian network structure. Our result showed that PROMs information is pivotal for predicting ED. However, combining both sources of information provides a better and well- calibrated structure. PD-0571 Patient reported lower limb edema after curative radiotherapy for prostate cancer L. Fokdal 1 , M. Berg 2 , A. Zedan 1 , H. Dahl Nissen 2 , L. Bentzen 1 , M. Svensson 1 , C. Vestergaard Madsen 1 1 Vejle Hospital, Department of Oncology, Vejle, Denmark; 2 Vejle Hospital, Radiotherapy Research Team, Department of Oncology, Vejle, Denmark Purpose or Objective Lower limb edema (LLE) is a known side effect to pelvic radiotherapy (RT). The present study provides a descriptive analysis of patient reported LLE in a cohort of prostate cancer patients treated with curative RT. Moreover, the impact of elective pelvic lymph node irradiation and other risk factors for LLE are analyzed. Materials and Methods A total of 340 prostate cancer patients treated with RT with or without androgen deprivation therapy (ADT) were enrolled in a prospective registration study in our department from 2017 to 2022. Disease outcomes, physician assessed morbidity and patient reported outcomes were recorded at baseline and during 5-years of follow-up. Patient reported LLE was assessed by use of EORTC QLQ-PR25. Information regarding patient reported LLE was available in 310 patients. These patients were included in the study. RT was prescribed according to risk group. Patients with low to intermediate-risk prostate cancer were treated with 60 Gy/20 fx or 78 Gy/39 fx to the prostate alone. Patients with high-risk disease were treated with 56 Gy/39 fx to the pelvic lymph nodes and seminal vesicles and a simultaneous integrated boost to the prostate alone ( ≤ T3a) or prostate and seminal vesicles (T3b) with 78 Gy/39 fx. Descriptive analysis of LLE was done with the calculation of prevalence rates at baseline and during each follow-up visit and with Kaplan-Meier statistics. Risk factors for LLE were analyzed univariate and multivariate with Cox regression analysis. These risk factors included age, ADT, surgical lymph node staging, Body Mass index (BMI), Charlson comorbidity index (CCI), and WHO performance status (PS). Results In the present study, 266 (85.8%) patients were treated with RT to the prostate, seminal vesicles and elective lymph nodes. The remaining 44 (14.2%) patients were treated with RT to the prostate alone. At a median follow-up of 15 (3-51) months, 49 (15.8%) patients had reported “quite a bit” of LLE while 21 (6.7%) patients reported “a lot” of LLE. The baseline prevalence rate of “quite a bit” and “a lot” of LLE was 5.0% and 0.8%, respectively. During follow-up the prevalence rate for “quite a bit” or “a lot” of LLE increased significantly to reach a plateau after 12 months follow-up where 9.0-13.5% and 2.0-3.4% of the patients reported “quite a bit” and “a lot” of LLE, respectively (figure 1). Risk factors for LLE in univariate analysis (elective lymph node irradiation (p=0.069), BMI (p<0.001), CCI (p=0.036), PS (p=0.091)) were analyzed in multivariate analysis. Only BMI (p=0.002) remained significantly associated with an increased risk for LLE after RT for prostate cancer (table 1).

Figure 1. Patient reported lower limb edema at baseline and during follow-up