Conversion to resectability uncommon in trials of unresectable mCRC patients

In clinical trials of patients with unresectable metastatic colorectal cancer (mCRC), conversion to resectability (C2R) rarely happens, reveals a study.

Prioritizing chemotherapeutic agents that increase C2R may improve overall survival (OS) of patients with unresectable mCRC, the researchers said.

A team of researchers conducted a prospectively registered systematic review (PROSPERO CRD42015024104) of randomized clinical trials published after 2003. C2R with a primary outcome of OS was the exposure of interest.

Clinical trials were categorized according to the difference in C2R between study arms: <2 percent, 2 percent to 2.9 percent, and ≥3 percent. Associations were measured using generalized estimating equations with adjustments for multiple observations from the same trial.

Of the 2,902 studies identified, 30 (n=13,618 patients) were included in the meta-analysis. The median C2R was 7.3 percent (interquartile range [IQR], 5 percent to 12.9 percent), with maximum C2R at 28.6 percent in the FOLFOX/FOLFIRI+cetuximab arm.

In C2R between two arms of the same study, the median difference was 2.3 percent (IQR, 1.3 percent to 3.4 percent), with a maximum difference reaching 15.4 percent in FOLFOX/FOLFIRI+cetuximab vs FOLFOX/FOLFIRI.

The median OS for the entire cohort was 20.7 months (IQR, 18.9‒22.7 months), with a between-group difference of 1.3 months (IQR, ‒1.2 to 3.6 months). Between the two study arms with <2 percent C2R difference, the median survival difference was 0.8 month compared with 1.6 months with ≥3 C2R rates.

Increasing C2R showed an incremental dose-effect response on OS (p=0.021). In addition, higher response rates were associated with C2R rates (p=0.003).

“Metastasectomy in patients with metastatic mCRC confers a significant survival benefit,” the researchers said.