Yttrium-90 Hepatic Radioembolization for Advanced Chemorefractory Metastatic Colorectal Cancer: Survival Outcomes Based on Right-Versus Left-Sided Primary Tumor Location.

Wu, Vincent; Li, Matthew D; Goodwin, J Scott; Wehrenberg-Klee, Eric P; Zurkiya, Omar; Kalva, Sanjeeva P; Ganguli, Suvranu

BACKGROUND: Primary colon cancer location in metastatic colorectal cancer (mCRC) affects survival. Outcomes based on primary tumor location after salvage hepatic radioembolization with Yttrium-90 resin microspheres (Y90) are not well studied. OBJECTIVE: To assess survival outcomes in patients with advanced chemorefractory mCRC treated with Y90 radioembolization, stratified by primary tumor location, and to explore potential factors predictive of survival. METHODS: A total of 99 patients with mCRC liver metastases progressive on systemic therapy treated with Y90 at a single center were retrospectively analyzed. In 89 patients, tumor response on first imaging follow-up (CT or MRI at 1.9 ± 0.9 months after Y90) was evaluated using RECIST. Overall survival (OS), post-Y90 OS, and hepatic progression-free survival (PFS) were calculated using the Kaplan-Meier method. Outcomes, and associations of outcomes with tumor response, were compared between patients with left- and right-sided tumors. RESULTS: A total of 74 patients had left-sided colon cancer, and 25 patients had right-sided colon cancer. Median OS from the time of mCRC diagnosis was 37.2 months, median post-Y90 OS was 5.8 months, and median hepatic PFS was 3.3 months. Based on RECIST, progressive disease on first imaging follow-up was observed in 38 patients (43%) post-Y90 and was associated with shorter post-Y90 OS compared to disease control on first imaging follow-up (4.0 vs 10.5 months, p < .001). Patients with right-sided primaries showed decreased post-Y90 OS compared to patients with left-sided primaries (5.4 vs 6.2 months, p = .02). Right- and left-sided primaries showed no significant difference in RECIST tumor response, hepatic PFS, or extrahepatic disease progression (p > .05). Post-Y90 survival was significantly lower in patients with progressive disease than with disease control among left-sided primaries (4.2 vs 13.9 months, p < .001), though not for right-sided primaries (7.2 vs 3.3 months, p = .05). CONCLUSION: Right-sided primary tumor was independently associated with decreased survival in patients with chemorefractory mCRC after Y90 radioembolization, despite similar RECIST tumor response, hepatic PFS, and extrahepatic disease progression compared to those with left-sided primary tumors. CLINICAL IMPACT: Primary colon cancer location impacts outcomes after salvage Y90 radioembolization and may help guide patient selection.