CURB your enthusiasm.

Headline: SBRT for oligoprogressive NSCLC significantly prolongs progression-free survival, but it does not appear to benefit a broad group of oligoprogressive breast cancer.

The Study: The CURB Trial was a phase 2 study that randomized 102 patients with metastatic breast (n=44) or non-small cell lung cancer (NSCLC, n=58) who had oligoprogression on systemic therapy to either standard further systemic therapy alone or the same plust SBRT to sites of oligoprogression. It is important to understand the big differences between de novo oligometastatic disease and oligoprogression. Oligometastatic disease can be relatively narrowly defined. Oligoprogression, on the other hand, is extremely broad. CURB was representative of the nature of oligoprogressive disease and included anyone with 5 or fewer progressing lesions. However, there was no limit on the amount of other lesions or overall burden of disease. Overall, SBRT significantly improved the primary endpoint of progression-free survival (PFS), but that improvement was driven exclusively by the NSCLC cohort who saw a jaw-dropping improvement in median PFS from 9 → 44 weeks. Conversely, there was no difference whatsoever with SBRT in the breast cohort, which was 17-18 weeks either way. Things can get really philosophical here, so check out the QuadCast to hear Dr. Tsai’s take on the outcomes of CURB. | Tsai, ASTRO 2021