Natural history of patients with subcentimeter pulmonary nodules undergoing hepatic resection for metastatic colorectal cancer

Background: CT imaging frequently detects subcentimeter pulmonary nodules (SPN) in patients undergoing resection of colorectal cancer liver metastases. Their clinical significance is unknown.

Study design: Patients were identified who underwent hepatic resection for colorectal cancer liver metastases between October 2004 and March 2006. The presence and imaging features of preoperative SPN were analyzed for their association with progression-free survival (PFS), disease-specific survival (DSS), and SPN progression.

Results: One hundred sixty patients underwent liver resection and 68 (43%) had SPN identified preoperatively. Median number of nodules was 1 (75(th) percentile: </=2 nodules) and median size of the largest was 3 mm (25(th) to 75(th) percentile: 2 to 5 mm). SPN were unilateral in 77%, calcified in 19%, solid in 92%, and smooth in contour in 95% of patients. At median follow-up of 31 months for survivors, SPN were proven to be metastatic disease in 35% of patients (24 of 68), either by radiographic increase in size or number (n = 12) or histologic confirmation after resection (n = 12). Median PFS for the 160 patients was 16 months and 3-year DSS was 78%. There was a trend toward shorter median PFS in patients with preoperative SPN compared with patients with no SPN (12 versus 20 months; p = 0.242). There was no difference in 3-year DSS (70% versus 83%; p = 0.46). SPN progression after hepatic resection did not substantially affect 3-year DSS. Calcified nodules were less likely to progress compared with noncalcified nodules (8% versus 42%; p = 0.03).

Conclusion: SPN are common among patients undergoing resection of colorectal cancer liver metastases and approximately one-third of these will prove to be metastatic disease. Presence of limited preoperative SPN might be associated with shorter PFS after hepatectomy, but does not substantially impact 3-year DSS, and should not necessarily preclude resection of hepatic metastases.