Rates of rectal toxicity in patients treated with high dose rate brachytherapy as monotherapy compared to dose-escalated external beam radiation therapy for localized prostate cancer.
Radiotherapy and Oncology : journal of the European Society for Therapeutic Radiology and Oncology
BACKGROUND: Using a prospectively collected institutional database, we compared 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. 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). EBRT patients underwent 3D image guidance via an off-line adaptive process.
RESULTS: Median follow-up was 7.5 years (7.4 years for EBRT and 7.9 years for HDR). 545 patients (20.3%) received HDR brachytherapy and 2138 (79.7%) EBRT. 69.1% of EBRT patients received IMRT. 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 versus EBRT, respectively. In those treated with IMRT, acute and chronic rates of any grade ≥2 GI toxicity were significantly reduced but remained significantly greater than those treated with HDR.
CONCLUSIONS: In appropriately selected patients with localized prostate cancer undergoing radiation therapy, HDR brachytherapy as monotherapy is an effective strategy for reducing rectal toxicity.
Parzen JS, Ye H, Gustafson G, Yan D, Martinez A, Chen PY, Ghilezan M, Sebastian E, Limbacher A, Krauss DJ. Rates of rectal toxicity in patients treated with high dose rate brachytherapy as monotherapy compared to dose-escalated external beam radiation therapy for localized prostate cancer. Radiother Oncol. 2020 Jun;147:123-129. doi: 10.1016/j.radonc.2020.03.033. Epub 2020 Mar 31. PMID: 32276193.