ABSTRACT
PURPOSE: Primary soft tissue sarcoma (STS) is rare, with many tumours occurring in extremities. Local management is limb-sparing surgery and pre-operative/post-operative radiotherapy (RT) for patients at high risk of local recurrence. We prospectively investigated late normal tissue toxicity and limb function observed after intensity modulated RT (IMRT) in extremity STS. METHODS AND MATERIALS: Patients with extremity STS, age ≥16 years. Two treatment cohorts: IMRT 50Gy in 25â¯×â¯2Gy fractions (pre-operative) or 60/66Gy in 30/33â¯×â¯2Gy fractions (post-operative). Primary endpoint was rate of ≥ grade 2 late subcutaneous fibrosis at 24 months after IMRT (RTOG late radiation morbidity scoring). RESULTS: One hundred and sixty-eight patients were registered between March 2016-July 2017. Of those, 159 (95%) received IMRT (106, 67% pre-operative RT and 53, 33% post-operative RT) with a median follow-up of 35.2 months (IQR: 32.9 to 36.6); 62% male; median age 58 years. Of 111 patients assessable for primary endpoint at 24 months, 12 (10.8%, 95%CI: 5.7%-18.1%) had ≥ grade 2 subcutaneous fibrosis. The overall rate at 24 months of RTOG late skin, bone and joint toxicity was 7/112 (6.3%), 3/112 (2.7%) and 10/113 (8.8%), respectively, and for Stern's scale oedema was 6/113 (5.3%). More wound complications were observed with pre-operative than post-operative RT (29.2% vs 3.8%). Overall survival at 24 months was 84.6%, and local recurrence event rate at 24 months was 10%. CONCLUSIONS: The rate of ≥ grade 2 subcutaneous fibrosis at 24 months after IMRT was 10.8%, consistent with other recent trials of IMRT, and lower than historical reported rates in patients treated with 3D-CRT. This trial provides further evidence for the benefits of IMRT in this patient population.
ABSTRACT
This study compares static conformal field (CF), intensity modulated radiotherapy (IMRT), and dynamic arcs (DA) for the stereotactic radiotherapy of base-of-skull meningiomas. Twenty-one cases of base-of-skull meningioma (median planning target volume [PTV] = 21.3 cm3) previously treated with stereotactic radiotherapy were replanned with each technique. The plans were compared for Radiation Therapy Oncology Group conformity index (CI) and homogeneity index (HI), and doses to normal structures at 6 dose values from 50.4 Gy to 5.6 Gy. The mean CI was 1.75 (CF), 1.75 (DA), and 1.66 (IMRT) (p < 0.05 when comparing IMRT to either CF or DA plans). The CI (IMRT) was inversely proportional to the size of the PTV (Spearman's rho = -0.53, p = 0.01) and at PTV sizes above 25 cm3, the CI (IMRT) was always superior to CI (DA) and CI (CF). At PTV sizes below 25 cm3, there was no significant difference in CI between each technique. There was no significant difference in HI between plans. The total volume of normal tissue receiving 50.4, 44.8, and 5.6 Gy was significantly lower when comparing IMRT to CF and DA plans (p < 0.05). There was significantly improved dose sparing for the brain stem and ipsilateral temporal lobe with IMRT but no significant difference for the optic chiasm or pituitary gland. These results demonstrate that stereotactic IMRT should be considered to treat base-of-skull meningiomas with a PTV larger than 25 cm3, due to improved conformity and normal tissue sparing, in particular for the brain stem and ipsilateral temporal lobe.
