Study designs of evaluations included in the review
No randomised controlled trials had been conducted in this field, so any prospective and retrospective studies fulfilling the remaining inclusion criteria were eligible for inclusion. The studies had to involve at least 40 patients, and have a minimum follow-up of 30 days for data on post-operative morbidity and mortality and at least 24 months for the inclusion of survival data. Only studies with recruitment of patients from 1980 were eligible. All of the identified studies were retrospective case series. Where reported, the median follow-up ranged from 20 to 62 months.
Specific interventions included in the review
Studies of surgical resection with curative intent of colorectal pulmonary metastases were eligible for inclusion. Studies of repeat pulmonary resection and hepatic and pulmonary resection were also included. Fourteen studies included R0 resections (no residual disease), five also included a small number of patients with R1 resections (histologic involved margins), and six gave no details. Surgical procedures included wedge, lobectomy, pneumonectomy and segmentectomy.
Participants included in the review
Studies were eligible if they assessed patients with pulmonary metastases from colorectal cancer. Where reported, the mean age of the patients was between 55 and 65 years (range: 23 to 85).
Outcomes assessed in the review
Studies were eligible if they assessed overall 5-year survival, operative mortality and post-operative mortality. Fourteen factors were consistently investigated with respect to prognostic relevance: patient demographics (age and gender), primary tumour characteristics (TNM, stage, histology, origin), lung metastases (number, size, laterality, type of resection, thoracic lymph node involvement), timing of metastases (disease-free interval), pre-thoracotomy carcinoembryonic antigen value, and different histological patterns of the primary and lung metastases.
How were decisions on the relevance of primary studies made?
The authors did not state how the studies were selected for the review, or how many reviewers performed the selection.