Left-sided primary tumor is a favorable prognostic factor for metastatic colorectal cancer patients receiving surgery

Prognostic value of primary tumor location in colorectal cancer: an updated meta-analysis

The clinical, histological, and molecular differences between right-sided colon cancer (RCC) and left-sided colon cancer (RCC) have received considerable attention. Over the past decade, many articles have been published concerning the association between primary tumor location (PTL) of colorectal cancer and survival outcomes. Therefore, there is a growing need for an updated meta-analysis integrating the outcomes of recent studies to determine the prognostic role of right vs left-sidedness of PTL in patients with colorectal cancer. We conducted a comprehensive database review using PubMed, SCOPUS, and Cochrane library databases from February 2016 to March 2023 for prospective or retrospective studies reporting data on overall survival (OS) and cancer-specific survival (CSS) of RCC compared with LCC. A total of 60 cohort studies comprising 1,494,445 patients were included in the meta-analysis. We demonstrated that RCC is associated with a significantly increased risk of death compared with LCC by 25% (hazard ratio (HR), 1.25; 95% confidence interval (CI), 1.19-1.31; I2 = 78.4%; Z = 43.68). Results showed that patients with RCC have a worse OS compared with LCC only in advanced stages (Stage III: HR, 1.275; 95% CI 1.16-1.4; P = 0.0002; I2 = 85.8%; Stage IV: HR, 1.34; 95% CI 1.25-1.44; P < 0.0001; I2 = 69.2%) but not in primary stages (Stage I/II: HR, 1.275; 95% CI 1.16-1.4; P = 0.0002; I2 = 85.8%). Moreover, a meta-analysis of 13 studies including 812,644 patients revealed that there is no significant difference in CSS between RCC and LCC (HR, 1.121; 95% CI 0.97-1.3; P = 0.112). Findings from the present meta-analysis highlight the importance of PTL in clinical decision-making for patients with CRC, especially in advanced stages. We provide further evidence supporting the hypothesis that RCC and LCC are distinct disease entities that should be managed differently.

Implication of primary tumor location for the indication of preoperative chemotherapy in patients with colorectal liver metastases

BACKGROUND

The benefit of preoperative chemotherapy for colorectal liver metastases (CRLM) remains uncertain. The aim was to clarify the effect of preoperative chemotherapy on CRLM according to the primary tumor location.

METHODS

Among a total cohort of 163 patients who underwent curative hepatectomy for CRLM, 36 patients had a right-sided and 127 had a left-sided primary tumor. According to the performance of preoperative chemotherapy, survival analysis was conducted and prognostic factors were identified.

RESULTS

Preoperative chemotherapy was administered to 17 patients (47.2%) with a right-sided and 74 (58.3%) with a left-sided primary tumor (P = 0.24). Among the patients who received preoperative chemotherapy, overall survival (OS) and disease-free survival (DFS) were similar between patients with right- and left-sided primary tumors (P = 0.36 and P = 0.44, respectively). Among the patients who underwent upfront hepatectomy, the OS and DFS of patients with a right-sided primary tumor were worse than those with a left-sided primary tumor (P = 0.02 and P = 0.025, respectively). Among the patients who underwent upfront surgery, the right-sided primary tumor was identified as an independent poor prognostic factor for OS (hazard ratio 3.44, P = 0.021).

CONCLUSION

The existence of a right-sided primary tumor may be an indication of preoperative chemotherapy for patients with CRLM.

The influence of tumour site on prognosis in metastatic colorectal carcinomas with primary tumour resection

PURPOSE

The aim of our study was to compare the characteristics and prognosis between right- and left-sided metastatic colorectal carcinomas.

METHODS

Data from 937 patients with stage IV colorectal carcinomas (synchronous distant metastasis) who had a resection of the primary tumour between 1985 and 2014 were analysed. Carcinomas in the caecum to transverse colon were defined as right-sided (n = 250; 26.7%). They were compared to tumours located from the splenic flexure to the rectum categorised as left-sided (n = 687; 73.3%).

RESULTS

In right-sided carcinomas, we observed significantly more female patients (50.8 vs 36.2%; p < 0.001), more unfavourable histological types (24.0 vs 8.6%; p < 0.001), more M1c carcinomas (metastases to the peritoneum ± others; 32.0 vs 14.4%; p < 0.001) and more emergencies (11.6 vs 7.1%; p = 0.029), while multimodal treatment was utilised in fewer patients (51.6 vs 63.8%; p = 0.001) and curative resections were less frequently (24.1 vs 35.4%; p = 0.002). Prognosis was significantly worse in patients with right-sided carcinomas (2-year-survival 27.2 vs 44.6%, p < 0.01). This difference was more pronounced after R2 resection (15.3 vs 29.7%; p < 0.001), than after macroscopic curative resection (2-year-survival 63.9 vs 71.9%; p = 0.106). In multivariate Cox regression analysis, tumour site was found to be an independent prognostic factor for overall survival (HR 1.2; 95% CI 1.0-1.5; p = 0.012). During the three 10-year periods, the prognosis improved equally in patients with right- and left-sided carcinomas, while the differences in survival remained identical.

CONCLUSIONS

In a surgical patient cohort undergoing primary tumour resection, significant differences in prognosis were observed between patients with metastatic right- and left-sided colorectal carcinomas.