Rectal toxicity results for patients treated with HDR brachytherapy as monotherapy versus dose-escalated external beam radiotherapy for localized prostate cancer.

5 Background: We present a large retrospective analysis comparing rectal toxicity following high dose rate (HDR) brachytherapy as monotherapy relative to dose-escalated external beam radiotherapy (EBRT) for patients with localized prostate cancer. Methods: 2683 patients treated with HDR or EBRT between 1994 and 2017 were included. 545 (20.3%) received HDR and 2138 (79.7%) EBRT. HDR fractionation was 38 Gy/4 fractions (n=321), 24 Gy/2 (n=96), or 27 Gy/2 (n=128). EBRT patients received a median dose of 75.6 Gy in 1.8 Gy fractions [range 70.2-82.8 Gy], using either 3D conformal or intensity modulated radiotherapy (IMRT). All EBRT patients underwent 3D image guidance via an off-line adaptive process. Treatment was directed to prostate only (n=780) or prostate and seminal vesicles (n=1351). No nodal therapy was given. Target volume for HDR patients included the prostate with no expansion. Acute and chronic gastrointestinal (GI) toxicity was defined as occurring ≤ 6 and > 6 months, respectively, after radiotherapy and was graded per CTCAE version 3.0. Toxicity variables were analyzed with χ2 test. Results: Median follow-up was 7.5 years (7.4 years for EBRT and 7.9 years for HDR). 69.1% of EBRT patients received IMRT with the remainder treated using 3D conformal technique. Compared to EBRT, HDR was associated with decreased rates of acute grade ≥ 2 diarrhea (0.7% vs. 4.5%, p < 0.001), rectal pain/tenesmus (0.6% vs. 7.9%, p < 0.001), and rectal bleeding (0% vs. 1.6%, p=0.001). Rates of chronic grade ≥ 2 rectal bleeding (1.3% vs. 8.7%, p < 0.001) and radiation proctitis (0.9% vs. 3.3%, p=0.001) favored HDR over EBRT. Rates of any chronic rectal toxicity grade ≥ 2 were 2.4% vs. 10.5% (p < 0.001) for HDR vs. EBRT, respectively. For the 1478 EBRT patients treated with IMRT, acute and chronic rates of any grade ≥ 2GI toxicity were 4.2% and 5.6%, respectively, compared to 1.5% (p=0.002) and 2.4% (p=0.002), respectively, for HDR patients. Conclusions: In appropriately selected patients with localized prostate cancer undergoing definitive radiation therapy, HDR brachytherapy as monotherapy is an effective strategy for reducing acute and chronic rectal toxicity.

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Timing of high-dose rate brachytherapy with external beam radiotherapy in intermediate and high-risk localized prostate cancer (THEPCA) patients and its effects on toxicity and quality of life: Results of a randomized feasibility trial.

Journal of Clinical Oncology ◽

10.1200/jco.2021.39.6_suppl.236 ◽

2021 ◽

Vol 39 (6_suppl) ◽

pp. 236-236

Author(s):

Imtiaz Ahmed ◽

Sharon Shibu Thomas ◽

Alexander Cain ◽

Jufen Zhang ◽

Sreekanth Palvai ◽

...

Keyword(s):

Prostate Cancer ◽

High Risk ◽

Dose Rate ◽

External Beam Radiotherapy ◽

High Dose Rate ◽

Localized Prostate Cancer ◽

High Dose ◽

External Beam ◽

Hdr Brachytherapy

236 Background: Advances in brachytherapy, external beam radiotherapy (EBRT) and image-guided radiotherapy have revolutionized radiotherapy delivery. Acute and late genitourinary (GU) and gastrointestinal (GI) toxicities remain a significant issue. Currently there is no European consensus on the timing of high-dose rate (HDR) brachytherapy in relation to EBRT. Schedules of HDR boost before or after EBRT vary significantly between institutions.The incidence of GI and GU toxicities was assessed in patients receiving HDR brachytherapy before and after EBRT. Methods: Men with Intermediate/high risk localized prostate cancer were randomized to Arm A (HDR brachytherapy before EBRT) or Arm B (HDR brachytherapy after EBRT). Both arms received a HDR boost of 15Gy and 46Gy in 23 fractions of EBRT. All patients received neoadjuvant and adjuvant hormone therapy for up to 2 years. Patients were followed quarterly up to a year. CTCAE scores for GU and GI toxicities were taken. IPSS, IEFL and FACT-P scores were collected. Fisher’s exact test was used to analyze the association between GU and GI toxicities. The T-test compared the mean differences in IPSS total scores at each follow-up. Analysis of variance evaluated the difference at follow up. Post-hoc testing and Bonferroni correction was applied. Results: 100 patients were randomized between 2015 and 2017. Data for 88 patients was available at cutoff. Mean age was 69 years (SD: 4.6). Age, Gleason score, TNM and clinical staging were similar in each arm. Mean IPSS Score was similar between both arms at baseline Arm A (6.52) & Arm B (6.57). 12 months follow up showed mild worsening of symptoms in both arms, but no significant difference noticed between Arm A (8.02) & Arm B (8.14) p=0.55. At 12 months, Grade 1 and 2 GU toxicities were more frequent in Arm A (22.88% & 5.28%, p=0.669) compared to Arm B (19.36% and 2.64%, p=0.485). Grade 1 GI toxicity was more common in Arm B (23.76%) than Arm A (21.2%), p=0.396. Grade 2 GI toxicities were more common in Arm A 5.28% vs 3.52%, p=0.739. Baseline mean IIEF scores were 10.9 and 10.53 in Arm A and B respectively. At 12 months this was 6.6 in Arm A and 7.11 in Arm B, but not statistically significant. FACT-P scores were not different in either arm, with good QOL scores maintained throughout. Mean score at baseline (125.18) was observed to be similar at 12 months follow up at (126.10). The PTV, CTV & OAR dose were compared and no significant differences were found. Conclusions: There were no significant differences in GI and GU related toxicities up to a year between patients receiving HDR brachytherapy before or after EBRT. There were no grade 3 or 4 toxicities. Treatment was well tolerated in both arms with good QOL scores. Longer follow up and a phase III multicenter RCT would be needed to validate findings. Clinical trial information: NCT02618161.

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