ESTRO 2023 - Abstract Book

S1244

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ESTRO 2023

and CSS. Genitourinary (GU) and gastrointestinal (GI) acute toxicity was observed in 57 % of patients; of them only 3,9 % had G2 and 0,78 % G3 (1 pt). Late GU and GI toxicity > G2 was 10,9 %, of them only five patients reported G3 late toxicity (3,9 %). Conclusion In our study, with a considerable median follow-up of 4 years, we found very good results in terms of bPFS, cPFS and excellent results regarding OS and CSS. Clinical recurrences before RT treatment, iPSA > 10 ng/ml, pT3b-pT4stage N1, PSA nadir < 0,04 ng/ml after RT treatment resulted prognostic factors regarding bPFS and cPFS. A particular attention must be in this subset of pts with high risk of recurrences, for an optimal RT treatment and attention follow-up. Overall, the RT treatment was well tolerated with acceptable acute and late toxicity. T. Iizumi 1 , T. Sawada 1 , M. Goto 1 , Y. Li 1 , T. Sumiya 1 , K. Baba 2 , M. Murakami 3 , T. Ishida 1 , Y. Hiroshima 4 , M. Nakamura 1 , Y. Sekino 1 , T. Saito 1 , D. Takizawa 5 , H. Makishima 1 , H. Numajiri 1 , M. Mizumoto 1 , K. Nakai 1 , H. Ishikawa 3 , H. Sakurai 1 1 University of Tsukuba, Department of Radiation Oncology and Proton Medical Research Center, Ibaraki, Japan; 2 Japanese Red Cross Medical Center, Department of Radiology, Tokyo, Japan; 3 National Institutes for Quantum Science and Technology, QST Hospital, Chiba, Japan; 4 Ibaraki Prefectural Central Hospital, Department of Radiation Oncology, Ibaraki, Japan; 5 Hitachi General Hospital, Department of Radiation Oncology, Ibaraki, Japan Purpose or Objective Patients of advanced age are susceptible to prostate cancer. With the current global trend of aging society, the number of elderly patients with prostate cancer is expected to increase. However, the optimal management for the elderly remains controversial. In the present study, we investigated long-term clinical outcomes of proton beam therapy (PBT) for elderly patients with localized prostate cancer. Materials and Methods Patients with localized prostate cancer underwent PBT in our institution between February 2010 to July 2015 were included in the present study and stratified into three groups: young, ages less than 65 years; young-old, 65 to 74 years; middle-old, 75 to 84 years. Low risk patients underwent PBT alone, while intermediate and high risk patients received neoadjuvant androgen deprivation therapy (ADT). High risk patients continued adjuvant ADT and the total period of ADT for high risk patients was three years. All the patients received a total dose of 70-78 in 28-39 fractions. Overall survival (OS), cause specific survival (CSS) and recurrence-free (RF) rates and occurrence rates of adverse events were calculated. Late toxicities were defined according to the Common Terminology Criteria for Adverse Events (CTCAE) version 5.0. Phoenix’s criteria of biochemical failure was adopted: a rise of ≥ 2 ng/mL above the nadir prostate-specific antigen after PBT, with or without ADT. Results Among 152 patients enrolled in this study, 45 patients were young, 80 were young-old, and 27 were middle-old. The median follow-up time was 110 months (range, 10-142 months). 10 (6.6%) low risk patients, 33 (21.7%) favorable intermediate patients, 14 (9.2%) unfavorable intermediate patients, 71 (46.7%) high risk patients and 24 (15.8%) very high risk patients constituted this cohort. A patient died of prostate cancer and nine patients of other causes. Prostate-specific antigen (PSA) failure was observed in 11 patients. The OS rates at 5 and 10 years for young, young-old, and middle old were 97.8% and 94.8%, 97.4% and 94.4%, and 92.4% and 73.5% (p = 0.12), while the corresponding CSS rates were 100.0% and 97.0%, 100.0% and 100.0%, 100.0% and 100.0% (p = 0.27). RF rates were at 5 and 10 years for young, young-old, and middle old were 92.8% and 83.1%, 100.0% and 91.9%, 100.0% and 100.0% (p = 0.09). The cumulative incidence rate of grade 2 or worse gastrointestinal toxicities at 1, 5 and 10 years for young, young-old, and middle-old were 0.0%, 4.5% and 4.5%, 1.2%, 3.8% and 3.8%, and 0.0%, 3.7% and 3.7% (p = 0.98), while the corresponding genitourinary toxicities were 0.0%, 0.0% and 0.0%, 1.2%, 5.2% and 5.2%, and 3.7%, 3.7% and 3.7% (p = 0.33). Conclusion The current study found no significant differences in disease control rate and toxicities among young, young-old, and middle-old patients with localized prostate cancer underwent PBT. Age alone should not be a barrier to PBT for localized prostate cancer. PO-1532 Long-term outcomes of proton beam therapy for elderly patients with prostate cancer

PO-1533 Applicability of SBRT for early prostate cancer and correlation with CTV variation during treatment

A. Angrisani 1 , R. Miceli 2 , L. Cedrone 2 , C. Rinaldi 2 , A. Frisone 2 , O. Ruggieri 2 , R.M. D'Angelillo 3

1 "L. Vanvitelli" University of Campania, Precision Medicine - Radiotherapy Unit, Naples, Italy; 2 Fondazione Policlinico “Tor Vergata”, Radiotherapy, Rome, Italy; 3 Fondazione Policlinico “Tor Vergata”, Department of Radiotherapy, Roma, Italy Purpose or Objective Stereotactic body radiation therapy (SBRT) for the treatment of early-stage prostate cancer (PCa) has increased over the last 5 years. The need to shorten the patient's stay in the clinic, the cost/effective benefits, the updates from non inferiority trials on SBRT versus the conventional RT and the high compliance of patients encourage its use. However, the