ESTRO 2024 - Abstract Book

S1723

Clinical - Lung

ESTRO 2024

the extent SF is non-inferior to MF on colorectal oligometastases which have previously been described as radioresistant.

Material/Methods:

Relevant articles were systematically identified using pre-determined search criteria with the aim of showing non inferiority. From the reports, 2-year LF was extracted and pooled using the method of inverse variance weighting to obtain 2-year LF estimates. Studies were divided based on origin (primary versus metastatic disease) as well as biological effective dose (BED), greater/equal to or less than 100Gy. Non-inferiority was assessed with one-sided comparisons.

Results:

A total of 133, 72 and 44 studies met the inclusion criteria for primary lung, pulmonary oligometastases of any primary and pulmonary oligometastases of colorectal primary respectively. For primary lung cancer, the pooled 2 year LF rates in the MF and SF BED > 100 groups were 10.7% {95% CI: 10.2-11.3, n=10069} and 8.8% {95% CI 6.9 11.2, n=745}, with evidence for non-inferiority for the SF cohort compared to the MF cohort. For patients with colorectal oligometastases receiving a BED > 100Gy, MF SABR demonstrated improved 2-year LF rates than SF, 24.3% vs 32.9%, p=0.02. For pulmonary oligometastases from any primary, the 2-yr LF rate for MF (n=2287) and SF (n=362) was 19.9% vs 23.0% respectively, p=0.09. The plausible true LF rate in the MF cohort could be as high as 21.7%, while in the SF cohort this is 27.9%. While formally not being statistically significant, the sample size of the SF cohort was only 16% of the MF cohort and there is insufficient evidence to support non-inferiority for SF in patients with pulmonary metastases. Patients treated with BED < 100Gy had inferior outcomes in all groups.

Conclusion:

For the treatment of primary lung cancer, there is no evidence for poorer 2-year LF rates in SF SABR (BED > 100) when compared to MF SABR (BED > 100) based on outcomes of over 10814 patients. However, selection bias may have applied as only two studies were randomised. MF SABR demonstrated improved 2-year LF rates compared to SF SABR for colorectal oligometastases. This can be interpreted as one additional LF expected at 2-years for every 12 patients treated with SF SABR. Data was underpowered to demonstrate non-inferiority for pulmonary oligometastases from any primary.

Keywords: SBRT, Lung

References:

1. Videtic GM, Paulus R, Singh AK, Chang JY, Parker W, Olivier KR, Timmerman RD, Komaki RR, Urbanic JJ, Stephans KL, Yom SS. Long-term follow-up on NRG Oncology RTOG 0915 (NCCTG N0927): A randomized phase 2 study comparing 2 stereotactic body radiation therapy schedules for medically inoperable patients with stage I peripheral non-small cell lung cancer. International Journal of Radiation Oncology* Biology* Physics. 2019 Apr 1;103(5):1077 84.