Top Line: Can a simultaneous integrated boost approach be used for post-operative treatment of soft tissue sarcoma?
The Study: Post-operative radiation for soft tissue sarcoma often requires treating large volumes and sequential cone-down boosts to the operative bed. This retrospective study evaluated the use of a simultaneous integrated boost approach for post-operative radiation for STS. It included 53 patients with mostly high grade (59%) extremity sarcomas (63%). The majority also had either close (36%) or microscopically positive (40%) margins. The authors’ SIB technique (termed “HARD”) delivered 50.4 Gy to the low-risk volume with a SIB of 63 Gy (R0, 45%), 64.4 Gy (R1, 19%), or 70 Gy (R2, 36%) to the high risk volume all in 28 fractions. The low-risk volume was the standard 3-4cm expansion along the muscle axis and 1.5cm radial expansion from the pre-op GTV and tumor bed. The high risk volume was a slightly smaller 2cm expansion along the muscle axis and 1cm radial expansion. At 2 years, local control was 100%. The rate of grade 3 toxicity was 7.5%, and all those events were transient acute dermatitis. When these plans were compared with sequential boost plans, there was a significantly lower volume that received 50 Gy as well as significantly lower dose to the bone and skin.
TBL: In this retrospective study, post-operative radiation for STS using a 28-fraction SIB approach delivered a high biologically effective dose with less integral dose to surrounding normal tissue and relatively low toxicity. | Mills, Adv Radiat Oncol 2023
The Study: Post-operative radiation for soft tissue sarcoma often requires treating large volumes and sequential cone-down boosts to the operative bed. This retrospective study evaluated the use of a simultaneous integrated boost approach for post-operative radiation for STS. It included 53 patients with mostly high grade (59%) extremity sarcomas (63%). The majority also had either close (36%) or microscopically positive (40%) margins. The authors’ SIB technique (termed “HARD”) delivered 50.4 Gy to the low-risk volume with a SIB of 63 Gy (R0, 45%), 64.4 Gy (R1, 19%), or 70 Gy (R2, 36%) to the high risk volume all in 28 fractions. The low-risk volume was the standard 3-4cm expansion along the muscle axis and 1.5cm radial expansion from the pre-op GTV and tumor bed. The high risk volume was a slightly smaller 2cm expansion along the muscle axis and 1cm radial expansion. At 2 years, local control was 100%. The rate of grade 3 toxicity was 7.5%, and all those events were transient acute dermatitis. When these plans were compared with sequential boost plans, there was a significantly lower volume that received 50 Gy as well as significantly lower dose to the bone and skin.
TBL: In this retrospective study, post-operative radiation for STS using a 28-fraction SIB approach delivered a high biologically effective dose with less integral dose to surrounding normal tissue and relatively low toxicity. | Mills, Adv Radiat Oncol 2023