Stereotactic body radiotherapy with periprostatic hydrogel spacer for localized prostate cancer: toxicity profile and early oncologic outcomes

Abstract

Background Multiple phase I-II clinical trials have reported on the efficacy and safety of prostate stereotactic body radiotherapy (SBRT) for the treatment of prostate cancer. However, few have reported outcomes for prostate SBRT using periprostatic hydrogel spacer (SpaceOAR; Augmenix). Herein, we report safety and efficacy outcomes from our institutional prostate SBRT experience with SpaceOAR placement. Methods Fifty men with low- or intermediate-risk prostate cancer treated at a single institution with linear accelerator-based SBRT to 3625 cGy in 5 fractions, with or without androgen deprivation therapy (ADT) were included. All patients underwent SpaceOAR and fiducial marker placement followed by pre-treatment MRI. Toxicity assessments were conducted at least weekly while on treatment, 1 month after treatment, and every follow-up visit thereafter. Post-treatment PSA measurements were obtained 4 months after SBRT, followed by every 3–6 months thereafter. Acute toxicity was documented per RTOG criteria. Results Median follow up time was 20 (range 4–44) months. Median PSA at time of diagnosis was 7.4 (2.7–19.5) ng/ml. Eighteen men received 6 months of ADT for unfavorable intermediate risk disease. No PSA failures were recorded. Median PSA was 0.9 ng/mL at 20 months; 0.08 and 1.32 ng/mL in men who did and did not receive ADT, respectively. Mean prostate-rectum separation achieved with SpaceOAR was 9.6 ± 4 mm at the prostate midgland. No grade ≥ 3 GU or GI toxicity was recorded. During treatment, 30% of men developed new grade 2 GU toxicity (urgency or dysuria). These symptoms were present in 30% of men at 1 month and in 12% of men at 1 year post-treatment. During treatment, GI toxicity was limited to grade 1 symptoms (16%), although 4% of men developed grade 2 symptoms during the first 4 weeks after SBRT. All GI symptoms were resolving by the 1 month post-treatment assessment and no acute or late rectal toxicity was reported > 1 month after treatment. Conclusions Periprostatic hydrogel placement followed by prostate SBRT resulted in minimal GI toxicity, and favorable early oncologic outcomes. These results indicate that SBRT with periprostatic spacer is a well-tolerated, safe, and convenient treatment option for localized prostate cancer. Electronic supplementary material The online version of this article (10.1186/s13014-019-1346-5) contains supplementary material, which is available to authorized users.

Feasibility of MR-guided ultrahypofractionated radiotherapy in 5, 2 or 1 fractions for prostate cancer

“…Given the strict OAR sparing employed in the UHF SBRT planning strategies presented, it is evident that physical optimisation of the patient's anatomy at each treatment session is critical to enabling maximal target coverage. The use of hydrogel rectal spacers to temporarily enlarge the perirectal space has been associated with low toxicity in the context of prostate SBRT [32,33]. Optimal bladder filling for MR-Linac prostate radiotherapy relies upon a careful balance between the presentation of a sufficiently full bladder to displace the small bowel superiorly and the patient's ability to comfortably hold their bladder for the duration of treatment [34].…”

Relationship between the invasion of lymphocytes and cytokines in the tumor microenvironment and the interval after single brachytherapy hypofractionated radiotherapy and conventional fractionation radiotherapy in non-small cell lung Cancer

“…The radiotherapy model for malignancy has transformed from conventional fraction radiotherapy (CFRT) to hypofractionated radiotherapy, which is now considered to be a new and highly effective mode of radiation therapy [1,2]. Stereotactic body radiotherapy (SBRT) and stereotactic radiosurgery are common procedures in hypofractionated radiotherapy, especially SBRT, which is widely performed for lung cancer, colorectal cancer, liver cancer, and prostate cancer, and shows considerable improvement in the radiotherapeutic outcomes [3][4][5][6][7][8].…”

Rectal Perforation Associated with Magnetic Resonance-Guided Radiation Therapy (MRgRT) after Peri-SpaceOAR Abscess Formation: A Case Report.

“…Furthermore, in pelvic radiation therapy, a hydrogel spacer is used to decrease the rectum dose [6][7][8][9]. In de nitive radiation therapy for prostate cancer, SpaceOAR, a hydrogel spacer, is widely used to decrease irradiated dose and toxicity of rectum [10][11]. A prospective randomized study revealed that insertion of SpaceOAR signi cantly reduced the rectum dose and toxicity, and improved bowel/urinary quality of life [12][13][14].…”