Prospective phase II trial on ablative stereotactic body radiation therapy (SBRT) for medically inoperable thoracic nodes metastases

BACKGROUND

Oligometastases in mediastinal nodes are increasingly prevalent, posing challenges for treatment with stereotactic body radiotherapy (SBRT) due to proximity to organs at risk (OARs). We report the results of a single prospective observational phase II trial on ablative SBRT for medically inoperable thoracic nodes metastases (NCT02970955).

MATERIAL AND METHODS

Since 2017, patients with < 3 nodal metastases were evaluated by the tumor board and included if deemed inoperable. SBRT was delivered using risk adaptive approach based on number, site and size of metastatic nodes (50 Gy/5fractions, 60 Gy/8fractions, 70 Gy/10 fractions). Planning target volume (PTV) partial underdosage was allowed. The primary end point was local control (LC) at 12 months. Secondary end points were: acute and late toxicities, overall survival (OS), progression free survival (PFS), and time to next systemic therapy (TTNS).

RESULTS

Between 03/2017-11/2021, 32 patients (41 nodal metastases) were included. NSCLC (13pts), breast (5pts) and colorectal cancer (4pts) were the most represented primary tumour. In 66 % cases, partial PTV undercoverage was necessary. LC at 1 and 2 years was 93.5 % and 82.3 %, respectively. Treatment was well-tolerated with no acute or late toxicity ≥ G3. Median OS was 59.7 months. OS at 1 and 2 years was 96.9 % and 83.8 % respectively. Median PFS was 12.2 months. PFS at 1 and 2 years was 53.1 % and 31.3 %, respectively.

CONCLUSION

This trial supported the feasibility and safety of ablative SBRT for thoracic nodes metastases thanks to risk adaptive approach allowing to delay of new systemic therapies. Larger studies are needed to confirm these observations.

Oligo metastatic renal cell carcinoma: stereotactic body radiation therapy, if, when and how?

BACKGROUND AND PURPOSE

Renal cell carcinoma (RCC) has traditionally been considered radioresistant with a limited role for conventional fractionation as a local approach. Nevertheless, since the appearance of stereotactic body radiation therapy (SBRT), radiotherapy (RT) has been increasingly employed in the management of metastatic RCC (mRCC). The aim of this study was to evaluate the role of SBRT for synchronous and metachronous oligo metastatic RCC patients in terms of local control, delay of systemic treatment, overall survival and toxicity.

PATIENTS AND METHODS

A Monocentric single institution retrospective data collection was performed. Inclusion criteria were: (1) oligo-recurrent or oligo-progressive disease (less than 5 metastases) in mRCC patients after radical/partial nephrectomy or during systemic therapy, (2) metastasectomy or other metastasis-directed, rather than SBRT not feasible, (3) any contraindication to receive systemic therapy (such as comorbidities), (4) all the histologies were included, (5) available signed informed consent form for treatment. Tumor response and toxicity were evaluated using the response evaluation criteria in solid tumors and the Common Terminology Criteria for Adverse Events version 4.03, respectively. Progression-free survival in-field and out-field (in-field and out-field PFS) and overall survival (OS) were calculated via the Kaplan-Meier method. The drug treatment-free interval was calculated from the start of SBRT to the beginning of any systemic therapy.

RESULTS

From 2010 to December 2018, 61 patients with extracranial and intracranial metastatic RCC underwent SBRT on 83 lesions. Intracranial and extracranial lesions were included. Forty-five (74%) patients were treated for a solitary metastatic lesion. Median RT dose was 25 Gy (range 10-52) in 5-10 fractions. With a median follow-up of 2.3 years (range 0-7.15), 1-year in-field PFS was 70%, 2-year in-field PFS was 55%. One year out-field PFS was 39% and 1-year OS was 78%. Concomitant systemic therapy was employed for only 11 (18%) patients, for the others 50 (82%) the drug treatment-free rate was 70% and 50% at 1 and 2 years, respectively. No > G1 acute and late toxicities were reported.

CONCLUSION

The pattern of failure was pre-dominantly out-of-field, even if the population was negatively selected and the used RT dose could be considered palliative. Therefore, SBRT appears to be a well-tolerated, feasible and safe approach in oligo metastatic RCC patients with an excellent in-field PFS. SBRT might play a role in the management of selected RCC patients allowing for a delay systemic therapy begin (one out of two patients were free from new systemic therapy at 2 years after SBRT). Further research on SBRT dose escalation is warranted.