ESTRO 2024 - Abstract Book

S1762

Clinical - Lung

ESTRO 2024

Adverse events were registered at 1, 3 and 12 weeks after treatment and from 6 months up to 3 years, patients were evaluated every 6 months, with additional examination 9 and 15 months after treatment. Events were scored according to NCI Common Terminology Criteria for Adverse Events, v4.0.

Results:

From 2018-2022 64 patients from 2 centers were enrolled within the study and dosimetry analysis was done for 60 patients. Fifty-one patients were diagnosed with NSCLC, 8 had SCLC and pathology was missing in one patient. 87% of patients were having a karnofsky performance score of ≥80. Median interval between first irradiation and reirradiation within our trial was 29 months. Conventionally fractionated radiotherapy has been used in 38 patients for reirradiation and stereotactic radiotherapy in the remaining 22 patients (50-52.5Gy in 5-7 fractions). Median volume of the PTV at time of reirradiation was 106cc. Median coverage of the PTV was 96%. Median dose of the prior treatment was 68Gy EQD 2,10 and median dose for re-irradiation was 60Gy EQD 2,10 . Median accumulated PTV Dmax of the reirradiation plan was 130Gy EQD 2,10 . Median D mean for the heart was 7.1Gy EQD 2,3 (range 0.03-39.8Gy EQD 2,3 ). Median accumulated V20 of lungs was 16.7% (range 1.9-31.9%) and median accumulated mean lung dose (MLD) was 15.3Gy EQD 2,3 (range 4.1-26.0Gy EQD 2,3 ). In 39 patients the accumulated dose in the bronchi was >80Gy, with a median D max of 106.3Gy EQD 2,3 . Twenty-six patients had a dose >80Gy EQD 2,3 in the trachea, having a median D max of 104.3Gy EQD 2,3 . In 20 patients the accumulated dose to the esophagus was >80Gy EQD 2,3 , with a median D max of 94.2Gy EQD 2,3 . Details about these subgroups and the spinal cord dose can be found in Table 1.

None of the patients reported grade 4 or 5 toxicity. Two patients reported grade 3 acute nausea/vomiting, both of them were receiving sequential chemoradiation. One patient had grade 3 pain complaints of the thoracic wall. Seven patients had grade 3 pneumonitis, 6 of these patients received sequential chemotherapy. Patients having grade 2-3 radiation pneumonitis had an significant higher accumulated median V20 in the lungs and a significant higher accumulated MLD compared to patients having grade 0-1 pneumonitis.

Overall survival and local control were 56% and 53 % at 2 years, respectively. Median follow-up was 26.5 months.