Chemotherapy in patients with a solitary colorectal liver metastasis - A nationwide propensity score matched study.

Introduction: Chemotherapy is widely used as an adjunct to surgery in the treatment of patients with resectable colorectal liver metastases. The aim of this study was to examine whether chemotherapy confers a survival benefit in patients with a solitary colorectal liver metastasis.

Methods: All consecutive patients between 2009 and 2017 in Sweden who were resected for a solitary colorectal liver metastasis were included. Patients treated with chemotherapy were compared with patients who had surgery alone. Unmatched and propensity score matched analyses were performed to compare overall survival, morbidity and mortality.

Results: Of 1224 eligible patients, 641 (52.4%) patients had chemotherapy, and 583 (47.6%) had surgery alone. After propensity score matching, two balanced groups with 102 patients in each, were analyzed. There was no difference in readmission within 30-days (p = 0.250), or morbidity, defined as Clavien-Dindo 3a or greater, between the groups (p = 0.761). There were no mortalities within ninety days. Radical resection margins were achieved in 92 (n = 94) per cent in the chemotherapy group, and 77 (n = 78) per cent in the surgery alone group (p = 0.016). Median overall survival was 91 (95% CI 73-109) months in the chemotherapy group, and 78 (95% CI 37-119) months in the surgery-alone group (p = 0.652).

Conclusion: This nationwide register-based study showed no difference in overall survival between patients treated with chemotherapy compared to surgery alone. Upfront surgery may be advisable in resectable solitary colorectal liver metastasis.