Synchronous Versus Metachronous Colorectal Liver Metastasis Yields Similar Survival in Modern Era.

BACKGROUND: Synchronous colorectal cancer liver metastasis (CRLM) has been viewed as being more aggressive and having shorter survival than metachronous disease. Advances in CRLM management led us to examine differences in treatment characteristics of synchronous versus metachronous CRLM patients along with survival and recurrence. MATERIALS AND METHODS: A retrospective review of hepatic resection for CRLM at a tertiary academic medical center was performed for two periods: a historic cohort from 1992 to 2010 (n = 121), and a modern cohort (n = 179) from 2012 to 2018. Clinical variables were compared between the patient groups, and survival outcomes were characterized. RESULTS: Five-year disease-specific survival for the modern synchronous group compared to the historic synchronous group was 71.7% versus 44.3% (P = 0.02). Modern metachronous versus modern synchronous 5-y disease-specific survival rates were 49.8% versus 71.7% (P = 0.31). Compared to the historic cohort, the modern one had significantly different timing of hepatic resection (P < 0.01) with increased use of liver-first (30.1% versus 7.5%) and simultaneous liver-colon resections (24.1% versus 10.4%), along with greater use of neoadjuvant chemotherapy (96.4% versus 65.6%; P < 0.01). Significantly more patients in the modern synchronous cohort had disease-free or alive-with-disease status at last follow-up, compared to the historic group (P < 0.01), and experienced less disease recurrence (62.7% versus 77.6%; P < 0.05). CONCLUSIONS: Modern synchronous CRLM patients who underwent hepatic resection experienced significantly improved survival compared to a historic cohort. We postulate that increased use of neoadjuvant chemotherapy and liver-first/simultaneous liver-colon resections in the modern synchronous cohort contributed to improved survival.