Conversion therapy with the intent to perform radical local treatment may not be suitable for patients with 10 or more liver metastases from colorectal cancer

BACKGROUND: The number of colorectal cancer liver metastases (CRLMs) is usually considered a contradictory indicator to surgical resection. However, some patients with initially unresectable CRLMs can receive radical local treatment after conversion therapy. This study aimed to evaluate the effect of radical local treatment after conversion therapy and the prognosis of patients with more than 10 initially unresectable CRLMs. METHODS: Data for a total of 229 patients with initially unresectable CRLMs were retrospectively reviewed between December 2012 and January 2020. Among these patients, 107 had ≥10 CRLMs, and 122 had <10 CRLMs. Overall survival (OS) and progression‐free survival (PFS) were used to reflect the prognosis of different groups of patients. Conversion therapy was defined as an initially unresectable liver metastasis converted into an R0 resectable lesion after systemic chemotherapy. Radical local treatment included hepatectomy and radiofrequency ablation (RFA). RESULTS: Patients with ≥10 CRLMs had a lower conversion rate (42.7% vs. 56.6%, p = 0.001). Baseline clinical N stage 1–2, ≥8 first‐line chemotherapy courses, and stable disease (SD) according to the Response Evaluation Criteria in Solid Tumours (RECIST) were independent factors predictive of conversion failure. Primary tumour location in the right colon, RECIST response of SD, and the absence of targeted therapy were independent factors predictive of unfavourable OS. The survival curves revealed that the OS of patients with or without conversion could be distinguished only among patients with <10 CRLMs (89.9% [95% CI, 82.5%–98.0%] vs. 58.9% [95% CI, 45.2%–76.7%], p < 0.001); this cut‐off point could also distinguish patients with a successful conversion outcome according to OS (89.9% [95% CI, 82.5–98.0%] vs. 58.2% [95% CI, 42.2–80.4%], p = 0.008). CONCLUSION: For CRLMs ≥ 10, patients with a successful conversion outcome cannot be distinguished from those without successful conversion outcome according to OS. Thus, conversion therapy with the intent to perform radical local treatment may not be suitable for patients with 10 or more liver metastases from colorectal cancer.