Conversion Chemotherapy for Unresectable Colorectal Liver Metastases: Are We Making a Difference?

Oligometastatic Colorectal Cancer: A Review of Definitions and Patient Selection for Local Therapies

PURPOSE

Nearly one-third of patients diagnosed with colorectal cancer (CRC) will ultimately develop metastatic disease. While a small percentage of patients can be considered for curative resection, more patients have limited disease that can be considered for local therapy. Challenges remain in defining oligometastatic CRC as well as developing treatment strategies guided by high level evidence.

METHODS

In this review, we present the challenges in defining oligometastatic CRC and summarize the current literature on treatment and outcomes of local therapy in patients with metastatic CRC.

RESULTS

For patients with liver- and/or lung-confined CRC metastases, surgical resection is the standard of care given the potential for long-term progression-free and overall survival. For patients with liver- or lung-confined disease not amenable to surgical resection, non-surgical local therapies, such as thermal ablation, hepatic arterial infusion pump (HAIP), or stereotactic body radiation therapy (SBRT), should be considered. For patients with more advanced disease, such as lymph node or bony metastases, the role of metastasis-directed therapy is controversial. Emerging data suggests that SBRT to ablate all metastases can improve progression-free and overall survival.

CONCLUSION

Multidisciplinary management is critical for patients with metastatic CRC due to the complexity of their cases and the nuanced patient, tumor, biological, and anatomical factors that must be weighed when considering local therapy. High-quality prospective randomized data in CRC are needed to further clarify the role of local ablative therapy in patients with unresectable oligometastatic CRC with ongoing studies including the RESOLUTE trial (ACTRN12621001198819) and the upcoming NCTN ERASur trial (NCT05673148).

Role of Hepatic Artery Infusion Chemotherapy in Treatment of Initially Unresectable Colorectal Liver Metastases: A Review

Importance

Although liver metastasis develops in more than half of patients with colorectal cancer, only 15% to 20% of these patients have resectable liver metastasis at presentation. Moreover, patients with initially unresectable colorectal liver metastasis (IU-CRLM) who progress on first-line systemic chemotherapy have limited treatment options. Hepatic arterial infusion chemotherapy (HAIC), in combination with systemic chemotherapy, leverages a multimodality approach to achieving control of hepatic disease and/or expanding resectability in patients with liver-only disease or liver-dominant disease.

Observations

Intra-arterial delivery of agents with high first-pass hepatic extraction (eg, floxuridine) limits systemic toxic effects and allows for administration of systemic chemotherapy at near-full doses. Hepatic arterial infusion chemotherapy in conjunction with systemic chemotherapy augments response rates up to 92% in patients who are chemotherapy naive, and up to 85% in pretreated patients with IU-CRLM. In turn, these responses translate into encouraging rates of conversion to resectability (CTR). Prospective trials have reported CTR rates as high as 52% in heavily pretreated patients with IU-CRLM who have an extensive hepatic disease burden. As such, CTR remains a compelling indication for liver-directed chemotherapy in this subset of patients. This review discusses the biological rationale for HAIC, evolution of rational combinations with systemic chemotherapy, contemporary evidence for CTR using HAIC and systemic chemotherapy, juxtaposition with rates of CTR using systemic chemotherapy alone, and morbidity and toxic effect profiles of HAIC.

Conclusions and Relevance

The argument is made for consideration of earlier initiation of HAIC in patients with IU-CRLM who are chemotherapy naive and for adoption of HAIC strategies to augment rates of resectability in patients who have failed first-line systemic chemotherapy before proceeding to second-line or third-line regimens.