ESTRO 2024 - Abstract Book

S2561

Clinical - Urology

ESTRO 2024

To evaluate the early gastrointestinal (GI) and genitourinary (GU) toxicities, as well as the PSA analysis after adaptive online stereotactic body radiation therapy (SBRT) for prostate cancer performed at our department.

Material/Methods:

From october 2021 to october 2023, 55 consecutive prostate patients were treated using the prescription of 36.25 Gy in 5 fractions delivered every other day. The mean age was 73 years (range: 49-85). Patients had low (20%), favorable intermediate (50,9%), unfavorable intermediate (27,3%) and high (1,8%) risk prostate cancer. Adjuvant hormonal treatment was used in 30,9% of patients. The median PSA before treatment was 6,6ng/ml (range: 1,29 16,98). Treatments were designed with the online adaptive SBRT procedure developed in our department using a C-arm conventional linac (Pract Radiat Oncol. 2022 Mar-Apr;12(2):e144-e152). It consists of full online replanning on the daily cone beam CT (CBCT) image acquired in every treatment session.

Early/late toxicity was reported using the Common Terminology Criteria for Adverse Events (CTCAE) genitourinary and gastrointestinal scale.

Results:

The maximum cumulative grade 1 and 2 early GU toxicity rates at the end of treatment were 54% and 5.45%, respectively. The maximum cumulative grade 1 and 2 early GI toxicity rates at the end of treatment were 29.9% and 7.27%, respectively. The maximum cumulative grade 1 and 2 early GI toxicity rates after 3 months of treatment were 5.45% and 1.8%, respectively. The maximum cumulative grade 1 and 2 early GU toxicity rates after 3 months of treatment were 23.6% and 0%, respectively.

No early grade 3 GU/GI toxicity were reported.

The most frequent symptoms were urinary frequency (GU) and diarrhea (GI).

The median 3 months after treatment PSA was 1.28 ng/ml. At a median of follow up of 12 months, 100% of patients were biochemically controlled.

Conclusion:

As far as we know, this is the first study reporting clinical outcomes for prostate SBRT patients treated with an online adaptive approach using a non-dedicated linac. Low incidence of early GI and GU toxicity were observed.

Keywords: Prostate, adaptative, SBRT