Dosimetric impacts of endorectal balloon in CyberKnife stereotactic body radiation therapy (SBRT) for early‐stage prostate cancer

Abstract

PurposeIn SBRT for prostate cancer, higher fractional dose to the rectum is a major toxicity concern due to using smaller PTV margin and hypofractionation. We investigate the dosimetric impact on rectum using endorectal balloon (ERB) in prostate SBRT.Materials and MethodsTwenty prostate cancer patients were included in a retrospective study, ten with ERB and 10 without ERB. Optimized SBRT plans were generated on CyberKnife MultiPlan for 5 × 7.25 Gy to PTV under RTOG‐0938 protocol for early‐stage prostate cancer. For the rectum and the anterior half rectum, mean dose and percentage of volumes receiving 50%, 80%, 90%, and 100% prescription dose were compared.ResultsUsing ERB, mean dose to the rectum was 62 cGy (P = 0.001) lower per fraction, and 50 cGy (P = 0.024) lower per fraction for the anterior half rectum. The average V50%, V80%, V90%, and V100% were lower by 9.9% (P = 0.001), 5.3% (P = 0.0002), 3.4% (P = 0.0002), and 1.2% (P = 0.005) for the rectum, and lower by 10.4% (P = 0.009), 8.3% (P = 0.0004), 5.4% (P = 0.0003), and 2.1% (P = 0.003) for the anterior half rectum.ConclusionsSignificant reductions of dose to the rectum using ERB were observed. This may lead to improvement of the rectal toxicity profiles in prostate SBRT.

Urethra-sparing stereotactic body radiotherapy for prostate cancer: how much can the rectal wall dose be reduced with or without an endorectal balloon?

“…A linac-based study [ 19 ] found that the presence of the ERB increased the volume of the R wall receiving high doses (V 95% and V 99% ) whereas no statistical difference was observed at an intermediate dose level (V 50% ). A Cyberknife-based study [ 20 ] observed that V 50% , V 80% , V 90% and V 100% were lower with an ERB.…”

Radiation-induced erectile dysfunction in patients with prostate cancer: current methods of radiotherapy

“…Снижение лучевой токсичности со стороны прямой кишки также реализуется путем использования эндоректального баллона [56]. Такой подход представляется неоднозначным, так как вызывает поджатие передней стенки прямой кишки к задней поверхности облучаемой ПЖ.…”

“…Такой подход представляется неоднозначным, так как вызывает поджатие передней стенки прямой кишки к задней поверхности облучаемой ПЖ. Вместе с тем в ряде радиотерапевтических клиник целесообразность введения эндоректального баллона объясняется отодвиганием задней стенки прямой кишки от зоны высокой дозы, созданием локальной компрессионной ишемии стенки прямой кишки, повышающей радиорезистентность облучаемых нормальных тканей, а также ограничением интрафракционного смещения ПЖ [56,57]. В рамках рассматриваемой проблемы представляет безусловный интерес работа M. Jaccard и соавт., описывающая влияние эндоректального баллона на дозовое распределение при планировании сосудосберегающей СТЛТ РПЖ (СОД 36,25 Гр за 5 фракций) [58].…”

The role and importance of SBRT in prostate cancer

“…Stereotactic radiotherapy can be used in various parts of the body due to noninvasive stabilization methods and the availability of taking target images during treatment. It has been started to be used in primer lung cancers and lung metastases, primary liver cancers and liver metastases, pancreatic cancers, prostate cancer, recurrent head and neck cancer, recurrent gynecologic cancers and many other types of cancer and in different regions (1-5).…”

“…Due to the low α/β ratio (1.4-3 Gy) of tumor cells in prostate cancer, high doses can be achieved. Therapeutic rate is also increased with hypofractionational application (2, 3, 5-6). Recently, SBRT has been started to be used in the treatment of prostate cancer in curative, salvage and boost treatments in the literature.…”