ESTRO 2024 - Abstract Book

S1822

Clinical - Lung

ESTRO 2024

All patients underwent 4D-CT (Aquilion Toshiba) or deep inspiration breath hold (DIBH) – CT and breath tracking with RPM system (VARIAN). ITV was delineated in all lesions. Almost all treatments were performed after 4D-CBCT imaging in free breathing, while 11% of lesions were treated with DIBH technique after DIBH-CBCT.

The median follow-up time was 15 months (range: 3-34 months).

The SBRT dose ranged from 40.0 to 60.0 Gy (median 50.0 Gy) and was administered in a median of 6 fractions.

The mean and median SUV values calculated before treatment were 8.1 and 6.9, respectively (range: 2-24).

We compared these initial values with those calculated over the course of the following four semesters. We noted a downward trend in both the mean and median values, indicating a partial and/or complete response according to the PERCIST criteria. We observed stabilisation of SUV at 6 months after the end of SBRT. At the 0-6-month interval, mean and median SUV values were 3.1 and 2.2 (range, 1- 6.9), respectively, with a ΔSuv of 62% and 68%, compared with the pretreatment SUV; at the 7-12-month interval, mean and median SUV values were 2.3 and 2, respectively (range, 1-4.7); in the 13-18-month interval, the mean and median SUV values were 2.1 and 2, respectively (range, 1.3-2.9); finally, in the 19-24-month interval, the mean and median SUV values were 2.2 and 2.0, respectively (range, 1.8-2.7) (Figure 1).

Within 3 months after completion of treatment, CR was observed in 3%, PR in 57%, and SD in 41%. Between 4 and 6 months after SBRT, radiological CR was observed in 19%, PR in 62%, and SD in 19%. Between 7 and 9 months after treatment, 38% of patients had CR, 57% had PR, and 5% had SD. Between 10 - 12 months, CR was observed in 68% of cases, PR in 27%, and SD in 5%. After more than 12 months, 95% of lesions had CR and only 5% had SD, although we did not observe any cases of PR (Figure 2).