Background — Resection of lung metastases is considered standard treatment for patients with metastatic colorectal cancer. We describe surgical management, prognostic factors, and outcomes in routine clinical practice.
Methods — All cases of colorectal cancer lung metastases (CRCLM) in Ontario, Canada resected during 2002-2009 were identified using the Ontario Cancer Registry and linked electronic records. Pathology reports were reviewed to identify extent of disease.
Results — The study population included 420 patients. Median age was 64 years; 60% were male. Sixty-one percent (256/420) had a solitary metastasis. Mean size of the largest metastasis was 2.4 cm. Lymph nodes were resected in 63% (263/420) of patients. Five-year cancer-specific survival (CSS) and overall survival (OS) was 42% (95%CI 37-47%) and 40% (95%CI 35-45%) respectively. On adjusted analyses, greater number (p<0.001) and size (p=0.001) of lesions and lymph node involvement (p<0.001) were associated with inferior CSS and OS. Lymph node positivity is strongly associated with survival (adjusted CSS HR 2.19 (95%CI 1.48-3.25); adjusted OS HR 2.08 (95%CI 1.41-3.07). Unadjusted 5 year CSS/OS are 49%/47% and 19%/19% for node negative and node positive disease respectively. The negative prognostic effect of size (>2cm) and number (>1) of lesions are additive: 5 year CSS/OS ranges from 57%/55% (single lesion <2 cm) to 24%/20% (multiple lesions, largest lesion>2cm).
Conclusions — Long-term survival of patients with resected CRCLM in routine practice is comparable to outcomes reported in institutional case series. Lymph node positivity is strongly associated with reduced survival. Combining size and number of metastatic lesions in advance of surgery may facilitate treatment decision-making.