Colorectal Metastases Affect on Survival in RAS Wild-Type Metastatic Colorectal Cancer

Researchers aimed to evaluate how the number and size of colorectal metastases affect survival and response to maintenance therapy in patients (pts) with RAS wild-type metastatic colorectal cancer.

The baseline study considered the number of CRMs (colorectal metastases) and the size of the largest CRM. They used a threshold (n≤/ > 10) for the median number of metastases to analyze the CRM count’s impact on progression-free survival (PFS) and overall survival (OS) during maintenance therapy. They used a threshold of ≤50mm to assess the effect of the largest CRM on these time-to-event endpoints. PFS and OS were analyzed using the Kaplan-Meier method and compared with log-rank tests. Hazard ratios (HR) with 95% CIs were calculated using Cox regression models.

Of 248 pts on maintenance therapy, 211 had evaluable CT and MRI scans (FU/FA+ panitumumab (Pmab), n = 106; FU/FA alone, n = 105). Initially, 50.1% had >10 CRMs, and the median largest CRM size was 45 mm. Having n≤10 CRMs was linked to better PFS, and both n≤10 CRMs and largest CRM ≤50mm were associated with improved OS compared to n>10 CRMs and largest CRM >50mm, respectively. In pts with >10 CRMs or the largest CRM >50mm, FU/FA+ Pmab showed significantly better PFS during maintenance therapy than FU/FA alone.

The study found high metastatic burden is a prognostic and predictive factor for maintenance therapy in RAS wild-type metastatic colorectal cancer. Pts with high metastatic burden at baseline may benefit particularly from Pmab-containing maintenance therapy.

Source: https://ascopubs.org/doi/abs/10.1200/JCO.2023.41.16_suppl.3551 

Clinical Trial: https://www.clinicaltrials.gov/study/NCT01991873