Population-based SEER analysis of survival in colorectal cancer patients with or without resection of lung and liver metastases

Abstract

Background: Approximately one third of all patients with CRC present with, or subsequently develop, colorectal liver metastases (CRLM). The objective of this population-based analysis was to assess the impact of resection of liver only, lung only and liver and lung metastases on survival in patients with metastatic colorectal cancer (mCRC) and resected primary tumor.

Methods: Ten thousand three hundred twenty-five patients diagnosed with mCRC between 2010 and 2015 with resected primary were identified in the Surveillance, Epidemiology and End Results (SEER) database. Overall, (OS) and cancer-specific survival (CSS) were analyzed by Cox regression with multivariable, inverse propensity weight, near far matching and propensity score adjustment.

Results: The majority (79.4%) of patients had only liver metastases, 7.8% only lung metastases and 12.8% metastases of lung and liver. 3-year OS was 44.5 and 27.5% for patients with and without metastasectomy (HR = 0.62, 95% CI: 0.58-0.65, P < 0.001). Metastasectomy uniformly improved CSS in patients with liver metastases (HR = 0.72, 95% CI: 0.67-0.77, P < 0.001) but not in patients with lung metastases (HR = 0.84, 95% CI: 0.62-1.12, P = 0.232) and combined liver and lung metastases (HR = 0.89, 95% CI: 0.75-1.06, P = 0.196) in multivariable analysis. Adjustment by inverse propensity weight, near far matching and propensity score and analysis of OS yielded similar results.

Conclusions: This is the first SEER analysis assessing the impact of metastasectomy in mCRC patients with removed primary tumor on survival. The analysis provides compelling evidence of a statistically significant and clinically relevant increase in OS and CSS for liver resection but not for metastasectomy of lung or both sites.

Keywords: Chemotherapy; Colorectal cancer; Liver metastasis; Lung metastasis; Propensity score analysis; Right and left sided tumor; Surgery; Surveillance epidemiology and end results database (SEER).

Fig. 1

Flow chart of patients’ cohort definition. Data from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute in the United States, covering approximately 28% of cancer cases in the United States were used for the present population-based analysis. Of 217,068 patients diagnosed with colorectal cancer between 2010 and 2015, 10,325 were eligible for analysis at the end of the selection process

Fig. 2

Forest plot of unadjusted and adjusted survival analysis stratified for metastatic site Analysis of survival was performed separately for patients with liver only, lung only, lung and liver being the metastatic site. The 95% confidence intervals for the hazard ratios were estimated using the Wald method and the P-values using the likelihood ratio test. The figure depicts the results for OS and CSS in unadjusted, multivariable adjusted, inverse propensity weight (IPW)-adjusted and exact matching and weighting propensity score adjusted analysis.

Fig. 3

Unadjusted and PS-adjusted survival analysis stratified for metastatic site. The upper three plots display the survival curves for cancer-specific survival in unadjusted analysis for patients with liver, lung and both metastasis with and without resection (Panel A to C). The lower three plots display the survival curves after exact propensity matching (Panel D to F)