Pulmonary metastasectomy in colorectal cancer: a systematic review and quantitative synthesis

Abstract

Objectives: Surgical removal of pulmonary metastases from colorectal cancer is undertaken increasingly but the practice is variable. There have been no randomized trials of effectiveness. We needed evidence from a systematic review to plan a randomized controlled trial.

Design: A formal search for all studies concerning the practice of pulmonary metastasectomy was undertaken including all published articles using pre-specified keywords. Abstracts were screened, reviewed and data extracted by at least two of the authors. Information across studies was collated in a quantitative synthesis.

Results: Of 101 articles identified, 51 contained sufficient quantitative information to be included in the synthesis. The reports were published between 1971 and 2007, and reported on 3504 patients. There was little change over time in patient characteristics such as age, sex, the time elapsed since resection of the primary cancer, its site or stage. The proportion with multiple metastases or elevated carcinoma embryonic antigen (CEA) did not change over time but there was an apparent increase in the proportion of patients who also had hepatic metastasectomy. Differences in 5-year survival between groups defined by CEA or by single versus multiple metastases persisted over time. Few data were available concerning postoperative morbidity, postoperative lung function or change in symptoms.

Conclusion: The quality of evidence available concerning pulmonary metastasectomy in colorectal cancer is not sufficient to draw inferences concerning the effectiveness of this surgery. There is great variety in what was reported and its utility. Given the burdensome nature of the surgery involved, better evidence, ideally in the form of a randomized trial, is required for the continuance of this practice.

Figure 1

Flow chart of papers found and progressive selection of 51 providing data in the quantitative synthesis

Figure 2

Cumulative number of pulmonary metastasectomy patients (n=3504 from 51 papers) with the mid-point and beginning and ending of case series shown. These dates were not given in two cases and were estimated as described in the text. The epochs contain 749, 626, 704, 708 and 717 cases, respectively

Figure 3

Data available in the 51 surgical follow-up studies ranked from left to right by diminishing number of element for which data were available

Figure 4

Percentage of patients who had multiple metastasectomy according to 38/51 papers in which data were presented