Are there recognized prognostic factors for patients undergoing pulmonary metastasectomy for colorectal carcinoma?

A best evidence topic in thoracic surgery was written according to a structured protocol. The question addressed was whether there is a specific subgroup of patients that would benefit from pulmonary metastasectomy for colorectal carcinoma (CRC). A total of 524 papers were identified using the reported search, of which 1 meta-analysis, 1 systematic review and 17 retrospective studies represented the best evidence to answer the clinical question. The authors, date, journal, country, study type, population, outcomes and key results are tabulated. Single pulmonary metastasis (PM) was identified as an independent prognostic favourable factor of survival in 5 of the studies (P = 0.059-0.001), whereas in 2 of the retrospective studies there was linear inverse correlation between the number of PMs and survival (P = 0.005-0.001). The presence of involved hilar and/or mediastinal lymph nodes was reported as a significant negative prognostic factor on multivariate analysis in 7 of the studies (P = 0.042 to <0.001), whereas the level and number of lymph node stations affected were not statistically significant. Seven studies showed an elevated pre-thoracotomy carcinoembrionic antigen (CEA) level (>5 ng/ml) to be a significant predictor of poor survival (P = 0.047-0.0008). In one of the studies, sublobar resection (wedge or segmentectomy) was associated with better survival compared with anatomic resection (P = 0.04). The size of the tumour (maximum diameter >3.75 cm) was associated with worse survival in 1 of the studies (P = 0.04), while another one reported size as a continuous variable to be a prognostic factor of poor survival. Synchronous chemotherapy (P = 0.027) on one study and neo-adjuvant chemotherapy prior to pulmonary metastasectomy (P = 0.0001) on another were found to be favourable prognostic factors, while disease progression during chemotherapy was associated with poor outcome in another paper (P < 0.0001). Patients older than 70 years were shown to have a worse prognosis in one of the studies. Rectal position of the tumour was associated with worse survival in one of the studies and worse disease-free interval in another one. Finally, one report showed no significant difference in terms of overall survival between thoracotomy and video-assisted thoracoscopic surgery groups. In conclusion, the prognostic factors for patients undergoing pulmonary metastasectomy for CRC include the size and number of metastases, intra-thoracic lymph node involvement, pre-thoracotomy CEA levels and the response to induction chemotherapy.