Complications after late (delayed) stereotactic radiosurgery boost in patients with non-small cell lung and breast cancer

The purpose of the work is the assessment of the functional state and the main complications after the delayed boost, depending on the level of doses used and the number of irradiated metastases. In 30 patients with non-small cell lung cancer (n=11) and breast cancer (n=19) with metastatic brain lesion after the end of WBRT, in the long term a boost (SRS) was performed. The prescribed dose for the late boost ranged from 10 to 22 Gy with a median of 15 Gy. Irradiation for single-fraction was performed in 26 patients (86.7%), for 2 fractions - in 2 patients (6.7%), for 3 fractions - in 2 patients (6.7%), respectively. As of December 2021, 26 of 30 patients (86.7%) died, only 53.3% from progression in the central nervous system, from complications 0%. Local progression (growth in the boost zone) was noted in 7 patients (23.3%), distant progression (the appearance of new metastasis or carcinomatosis) - in 56.7%. Often, patients had a combined lesion. Increasing the dose with a delayed boost of ≥15 Gy did not affect the functional state of patients after 12 (p=0.767), 24 (p=0.820), and 36 months (p=1.0) after WBRT. The late boost did not lead to a significant increase in cognitive impairment (p=0.437), despite the larger number of radiosurgical targets and the high dose level compared to the standard boost. There were no significant differences (p=0.935) in the frequency of radionecrosis in groups with a boost dose of ≥15 Gy and function show_eabstract() { $('#eabstract1').hide(); $('#eabstract2').show(); $('#eabstract_expand').hide(); }