Prognostic Impact of Palliative Primary Tumor Resection for Unresectable Stage 4 Colorectal Cancer: Using a Propensity Score Analysis
The benefits that palliative resection of the primary tumor offers patients with unresectable stage 4 colorectal cancer, specifically with regard to overall survival, are controversial, and the issue is complicated by marked differences in patient backgrounds and characteristics.
The study enrolled 770 consecutive patients with unresectable stage 4 colorectal cancer referred to the divisions of surgery or gastrointestinal oncology at the National Cancer Center Hospital from 1997 to 2013. Of these patients, 429 (56 %) underwent palliative resection of the primary tumor, whereas 341 (44 %) did not. To lessen the effects of confounding factors between the groups, including age, year, severe symptoms, number of organs involved by metastases, primary tumor site, and carcinoembryonic antigen (CEA) value, propensity score analyses were used for regression adjustment, stratification, and matching, with overall survival as the primary end point.
The regression adjustment including the propensity score as a linear predictor in the model showed that palliative resection was associated with a significantly improved overall survival (hazard ratio [HR] 0.60; 95 % confidence interval [CI] 0.50–0.71; p < 0.01)]. Stratification analysis showed that in all five strata, palliative resection was associated with better overall survival (HR 0.43–0.73). Similarly, the propensity score-matched cohort (267 matched pairs) yielded an HR of 0.58 (95 % CI 0.48–0.70; p < 0.01).
The findings suggest that palliative resection of the primary tumor may be associated with improved overall survival. Further investigations such as prospective randomized trials are needed to confirm this result.
KeywordsColorectal Cancer Overall Survival Propensity Score Propensity Score Match Palliative Resection
The authors thank two statisticians, J. Mizusawa and T. Shibata, both at the Center for Research Administration and Support at the National Cancer Center, for their assistance. The authors also thank M. Moriya, Y. Shimada, T. Akasu, S. Fujita, and S. Yamamoto, all of whom served as former staff members in our divisions.
Conflict of interest
There are no conflicts of interest.
- 8.Ferrand F, Malka D, Bourredjem A, et al. Impact of primary tumour resection on survival of patients with colorectal cancer and synchronous metastases treated by chemotherapy: results from the multicenter, randomised trial Federation Francophone de Cancerologie Digestive 9601. Eur J Cancer. 2013;49:90–7.CrossRefPubMedGoogle Scholar
- 10.Faron M, Pignon JP, Malka D, et al. Is primary tumour resection associated with survival improvement in patients with colorectal cancer and unresectable synchronous metastases? A pooled analysis of individual data from four randomised trials. Eur J Cancer. 2015;51:166–76.CrossRefPubMedGoogle Scholar
- 17.t Lam-Boer J, Mol L, Verhoef C, et al. The CAIRO4 study: the role of surgery of the primary tumour with few or absent symptoms in patients with synchronous unresectable metastases of colorectal cancer: a randomized phase III study of the Dutch Colorectal Cancer Group (DCCG). BMC Cancer. 2014;14:741.Google Scholar
- 18.Rahbari NN, Lordick F, Fink C, et al. Resection of the primary tumour versus no resection prior to systemic therapy in patients with colon cancer and synchronous unresectable metastases (UICC stage IV): SYNCHRONOUS: a randomised controlled multicentre trial (ISRCTN30964555). BMC Cancer. 2012;12:142.CrossRefPubMedPubMedCentralGoogle Scholar