PURPOSE: Mesenchymal tumours require high-dose radiation therapy (RT). Small bowel (SB) dose constraints have historically limited dose delivery to paraspinal and retroperitoneal targets. This retrospective study correlated SB dose-volume histograms with side-effects after proton radiation therapy (PT). PATIENTS AND METHODS: Between 1997 and 2008, 31 patients (mean age 52.1 years) underwent spot scanning-based PT for paraspinal/retroperitoneal chordomas (81%), sarcomas (16%) and meningiom (3%). Mean total prescribed dose was 72.3 Gy (relative biologic effectiveness, RBE) delivered in 1.8-2 Gy (RBE) fractions. Mean follow-up was 3.8 years. Based on the pretreatment planning CT, SB dose distributions were reanalysed. RESULTS: Planning target volume (PTV) was defined as gross tumour volume (GTV) plus 5-7 mm margins. Mean PTV was 560.22 cm(3). A mean of 93.2% of the PTV was covered by at least 90% of the prescribed dose. SB volumes (cm(3)) receiving doses of 5, 20, 30, 40, 50, 60, 70, 75 and 80 Gy (RBE) were calculated to give V5, V20, V30, V40, V50, V60, V70, V75 and V80 respectively. In 7/31 patients, PT was accomplished without any significant SB irradiation (V5=0). In 24/31 patients, mean maximum dose (Dmax) to SB was 64.1 Gy (RBE). Despite target doses of >70 Gy (RBE), SB received >50 and >60 Gy (RBE) in only 61 and 54% of patients, respectively. Mean SB volumes (cm(3)) covered by different dose levels (Gy, RBE) were: V20 (n=24): 45.1, V50 (n=19): 17.7, V60 (n=17): 7.6 and V70 (n=12): 2.4. No acute toxicity ≥ grade 2 or late SB sequelae were observed. CONCLUSION: Small noncircumferential volumes of SB tolerated doses in excess of 60 Gy (RBE) without any clinically-significant late adverse effects. This small retrospective study has limited statistical power but encourages further efforts with higher patient numbers to define and establish high-dose threshold models for SB toxicity in modern radiation oncology.
PURPOSE: Mesenchymal tumours require high-dose radiation therapy (RT). Small bowel (SB) dose constraints have historically limited dose delivery to paraspinal and retroperitoneal targets. This retrospective study correlated SB dose-volume histograms with side-effects after proton radiation therapy (PT). PATIENTS AND METHODS: Between 1997 and 2008, 31 patients (mean age 52.1 years) underwent spot scanning-based PT for paraspinal/retroperitoneal chordomas (81%), sarcomas (16%) and meningiom (3%). Mean total prescribed dose was 72.3 Gy (relative biologic effectiveness, RBE) delivered in 1.8-2 Gy (RBE) fractions. Mean follow-up was 3.8 years. Based on the pretreatment planning CT, SB dose distributions were reanalysed. RESULTS: Planning target volume (PTV) was defined as gross tumour volume (GTV) plus 5-7 mm margins. Mean PTV was 560.22 cm(3). A mean of 93.2% of the PTV was covered by at least 90% of the prescribed dose. SB volumes (cm(3)) receiving doses of 5, 20, 30, 40, 50, 60, 70, 75 and 80 Gy (RBE) were calculated to give V5, V20, V30, V40, V50, V60, V70, V75 and V80 respectively. In 7/31 patients, PT was accomplished without any significant SB irradiation (V5=0). In 24/31 patients, mean maximum dose (Dmax) to SB was 64.1 Gy (RBE). Despite target doses of >70 Gy (RBE), SB received >50 and >60 Gy (RBE) in only 61 and 54% of patients, respectively. Mean SB volumes (cm(3)) covered by different dose levels (Gy, RBE) were: V20 (n=24): 45.1, V50 (n=19): 17.7, V60 (n=17): 7.6 and V70 (n=12): 2.4. No acute toxicity ≥ grade 2 or late SB sequelae were observed. CONCLUSION: Small noncircumferential volumes of SB tolerated doses in excess of 60 Gy (RBE) without any clinically-significant late adverse effects. This small retrospective study has limited statistical power but encourages further efforts with higher patient numbers to define and establish high-dose threshold models for SB toxicity in modern radiation oncology.
Authors: C G Willett; C J Ooi; A L Zietman; V Menon; S Goldberg; B E Sands; D K Podolsky Journal: Int J Radiat Oncol Biol Phys Date: 2000-03-01 Impact factor: 7.038
Authors: Kathy L Baglan; Robert C Frazier; Di Yan; Raywin R Huang; Alvaro A Martinez; John M Robertson Journal: Int J Radiat Oncol Biol Phys Date: 2002-01-01 Impact factor: 7.038
Authors: Harald Paganetti; Andrzej Niemierko; Marek Ancukiewicz; Leo E Gerweck; Michael Goitein; Jay S Loeffler; Herman D Suit Journal: Int J Radiat Oncol Biol Phys Date: 2002-06-01 Impact factor: 7.038
Authors: Susanne Burdak-Rothkamm; Andrea Smith; Pavel Lobachevsky; Roger Martin; Kevin M Prise Journal: Strahlenther Onkol Date: 2014-09-23 Impact factor: 3.621
Authors: Constantin Dreher; Daniel Habermehl; Swantje Ecker; Stephan Brons; Rami El-Shafie; Oliver Jäkel; Jürgen Debus; Stephanie E Combs Journal: Radiat Oncol Date: 2015-11-21 Impact factor: 3.481