ESTRO 2024 - Abstract Book

S1937

Clinical - Mixed sites, palliation

ESTRO 2024

Purpose/Objective:

The adrenal glands are a common site of metastasis of several primary tumors, such as lung cancer, breast cancer and melanoma. Surgical resection was considered the standard treatment until a few years ago, not always being a feasible option due to difficulties related to the anatomical site, patient and/or disease characteristics. Stereotactic body radiotherapy body radiotherapy (SBRT) represents a promising local treatment, with good results of local control and lower toxicity for patients presenting adrenal oligometastases. The aim of this study is to assess the local control of SBRT on adrenal metastatic lesions.

Material/Methods:

This is a retrospective study in which patients with oligometastatic or oligoprogressive disease at the adrenal glands, and who were treated with SBRT, between 2017 and 2022 were evaluated. Patient characteristics, tumor and treatments received were collected and analyzed. For better analysis and correlation with local control, three groups were established according to tumor size (< 2 cm, 2 - 5 cm and > 5 cm) and two other groups according to the effective biological dose achieved (< 72 Gy and ≥72 Gy).

Results:

A total of 18 patients (8 females and 10 males) were included, with a median age of 66 years, and 19 metastatic lesions, 6 of which were right and 13 left. The median follow-up was 13 months.

The most frequent primary tumor was non-small cell lung cancer (63%) with adrenal disease being the only disease at diagnosis in 26% of cases.

The median total dose in SBRT performed was 40 Gy (range 30 - 56 Gy), in a median of 5 fractions and with a median biologic effective dose for a α/β of 10 (BED10) of 72 Gy (range 48 - 100 Gy), with 57.9% having received ≥72 Gy of BED10 and 42.1% having received a BED10 < 72 Gy.

The median pre-treatment adrenal lesion size was 2 cm (42.1% < 2 cm, 52.6% 2 - 5 cm and 5.3% > 5 cm) and 1.1 cm after receiving SBRT treatment.

Of the 19 lesions treated, 2 showed complete response, 11 showed partial response, 4 were stabilized and only 2 of them progressed after the first re-evaluation.

Only 5 patients presented acute toxicity, consisting of mild asthenia, and only 1 patient developed long-term adrenal insufficiency.

Of those patients who presented symptoms related to adrenal metastasis (10.5%), 100% presented improvement during follow-up.

Local control at one year was 84.2% and at the end of the follow-up period 68.4%, with a median time to local relapse of 21 months.

Disease progression (median 6 months) occurred in 89.5% of patients during follow-up.