The impact of primary tumor resection for asymptomatic colorectal cancer patients with unresectable metastases: a systematic review and meta-analysis

Background Whether patients with asymptomatic primary tumors and unresectable metastases of colorectal cancer (CRC) should undergo primary tumor resection (PTR) remains controversial. This study aims to determine the appropriateness of PTR for these individuals by evaluating a number of outcome measures. Methods A systematic literature search was performed. Outcome measures included overall survival, emergency surgery rates, incidence of postoperative complications, time to initiate chemotherapy, conversion rates, and chemotherapy-related toxicities. Results Patients who received PTR in addition to chemotherapy had a better overall survival rate than those who only received chemotherapy (HR = 0.62, 95%CI, 0.50–0.78, I 2 = 84%, p < 0.00001). In the RCT subgroup, there were no significant differences with a HR of 0.72 (95%CI, 0.45–1.13, I 2 = 17%, p = 0.15). More patients in the chemotherapy alone group could be converted to resectable status (OR = 0.47, 95%CI, 0.27–0.82, I 2 = 0%, p = 0.008), but the incidence of emergency surgery was 23% (95%CI, 17–29%, I 2 = 14%). The risk of chemotherapy-related toxicity was not significantly higher in the PTR group (OR = 1.5, 95%CI, 0.94–2.43, p = 0.09, I 2 = 0%), with a 7% incidence of postoperative complications (95%CI, 0–14%, p = 0.05, I 2 = 0%). The time to initiate chemotherapy after PTR was approximately 33.06 days (95%CI, 25.55–40.58, I 2 = 0%). Conclusion PTR plus chemotherapy may be associated with improved survival in asymptomatic CRC patients with unresectable metastases. However, PTR did not provide a significant survival benefit in the subgroup of RCTs. Additionally, PTR did not result in a significantly increased risk of chemotherapy-related toxicity, with a postoperative complication rate of approximately 7%, and chemotherapy could be initiated at approximately 33.06 days after PTR. Compared with the PTR plus chemotherapy, chemotherapy alone could result in a significantly higher conversion rate. However, about 23% of patients receiving chemotherapy alone required emergency surgery for primary tumor-related symptoms. The above results needed to be validated in future larger prospective randomized trials.