ESTRO meets Asia 2024 - Abstract Book

S282

Interdisciplinary – Urology

ESTRO meets Asia 2024

42

Digital Poster

Hypofractionated simultaneous integrated boost with pelvic nodal irradiation for prostate cancer

Lekshmi R, Deepa M Joseph, Namitha R S, Harpreet Kaur, Sweety Gupta, Manoj Gupta

Radiation Oncology, All India Institute of Medical Sciences, Rishikesh, India

Purpose/Objective:

Our study investigated the dosimetric parameters and late toxicity profiles of patients with unfavourable intermediate, high-risk, and very high-risk carcinoma prostate who underwent hypofractionated simultaneous integrated boost (SIB) radiation therapy.

Material/Methods:

In this study, we treated 10 patients diagnosed with unfavourable intermediate, high-risk, and very high-risk prostate cancer using Simultaneous Integrated Boost Intensity Modulated Radiotherapy by Volumetric Modulated Arc Therapy (VMAT) or Intensity Modulated Radiotherapy (IMRT) technique. Each patient received a total dose of 66 - 68 Gy (2.64 - 2.72 Gy/fraction) to the prostate and seminal vesicles and 50 Gy (2.0 Gy/fraction) to the pelvic lymph nodes over 25 fractions. Furthermore, all patients received androgen deprivation therapy tailored to their disease risk category. We evaluated the dosimetric parameters and Radiation Therapy Oncology Group (RTOG) late gastrointestinal and genitourinary toxicities.

Results:

The mean age of our study population was 65 years (Range: 42-76 years). Most of the patients (70%) had a ECOG performance status of 1 and had no known co-morbidities. Most of the patients had a Gleason Score of 7 and belonged to the National Comprehensive Cancer Network (NCCN) high risk category .The majority of patients (77%) received 68 Gy in 25 fractions to the prostate, while 23% received 66 Gy in 25 fractions. The majority of patients (90%) were treated using the Volumetric Modulated Arc Therapy (VMAT) technique, with the remaining 10% receiving Intensity Modulated Radiotherapy (IMRT). The median follow-up time was 25 months. The study found that the mean volume of the prostate planning target volume (PTV) receiving 95% of the prescribed dose was 98.76%, while for the pelvic nodal PTV, it was 98.60%. Regarding bladder dose, the mean values for V30Gy, V45Gy, V50Gy, and V60Gy were 82%, 45.5%, 32.6%, and 13.2% respectively. For the rectum, the mean values for V30Gy, V45Gy, V50Gy, and V60Gy were 81.4%, 50.5%, 40%, and 24.5% respectively. The mean volume of bowel bag receiving 40 Gy was 323.8 cc and the mean penile bulb V40Gy was 55.25 %.One patient experienced grade 1 acute gastrointestinal (GI) toxicity, and grade 1 and 2 late rectal toxicities were observed in one patient each. All patients are currently alive and on follow-up, and none have reported grade 3 or 4 toxicities up to this point.

Organ at risk

Mean dose

Bladder

V30Gy=82%

V45Gy=45.5%