Rectal Radiation Dose and Clinical Outcomes in Prostate Cancer Patients Treated With Stereotactic Body Radiation Therapy With and Without Hydrogel

Palak Kundu; Eric Y Lin; Stephanie M Yoon; Neil R Parikh; Dan Ruan; Amar U Kishan; Alan Lee; Michael L Steinberg; Albert J Chang

doi:10.3389/fonc.2022.853246

Rectal Radiation Dose and Clinical Outcomes in Prostate Cancer Patients Treated With Stereotactic Body Radiation Therapy With and Without Hydrogel

Front Oncol. 2022 Mar 8:12:853246. doi: 10.3389/fonc.2022.853246. eCollection 2022.

Authors

Palak Kundu¹, Eric Y Lin^{1

2}, Stephanie M Yoon¹, Neil R Parikh¹, Dan Ruan¹, Amar U Kishan¹, Alan Lee¹, Michael L Steinberg¹, Albert J Chang¹

Affiliations

¹ Department of Radiation Oncology, David Geffen School of Medicine at UCLA, Los Angeles, CA, United States.
² David Geffen School of Medicine at UCLA, Los Angeles, CA, United States.

Abstract

Background: Patients with prostate cancer treated with stereotactic body radiation therapy (SBRT) may experience gastrointestinal (GI) toxicity. The hydrogel may mitigate this toxicity by reducing the rectal radiation dose. The purpose of this study is to compare rectal radiation dose and GI toxicity in patients receiving prostate SBRT with and without hydrogel.

Methods: Consecutive patients treated with SBRT between February 2017 and January 2020 with and without hydrogel were retrospectively identified. Baseline characteristics including prostate volume, rectal diameter, body mass index (BMI), age, pretreatment prostate-specific antigen (PSA), Gleason score, T-stage, and androgen deprivation therapy (ADT) usage were compared. Dosimetric outcomes (V40Gy, V36Gy, V32Gy, V38Gy, and V20Gy), rates of acute (≤90 days) and late (>90 days) GI toxicity, and PSA outcomes were evaluated for patients with and without hydrogel.

Results: A total of 92 patients were identified (51 hydrogel and 41 non-hydrogel). There were no significant differences in baseline characteristics. Rectal V38(cc) was significantly less in the hydrogel group (mean 0.44 vs. mean 1.41 cc, p = 0.0002), and the proportion of patients with V38(cc) < 2 cc was greater in the hydrogel group (92% vs. 72%, p = 0.01). Rectal dose was significantly lower for all institutional dose constraints in the hydrogel group (p < 0.001). The hydrogel group experienced significantly less acute overall GI toxicity (16% hydrogel vs. 28% non-hydrogel, p = 0.006), while the difference in late GI toxicity trended lower with hydrogel but was not statistically significant (4% hydrogel vs. 10% non-hydrogel, p = 0.219). At a median follow-up of 14.8 months, there were no biochemical recurrences in either group.

Conclusion: Hydrogel reduces rectal radiation dose in patients receiving prostate SBRT and is associated with a decreased rate of acute GI toxicity.

Keywords: SBRT (stereotactic body radiation therapy); hydrogel; outcomes; prostate cancer; radiation oncology.