Background: Adjuvant chemotherapy for patients with stage III (node-positive) colorectal cancer (CRC) reduces mortality by one third. Retrieval of an inadequate number of lymph nodes in the surgical specimen may result in incorrectly designating some patients as stage II (node negative), and consequently, such patients may not be offered appropriate chemotherapy. Recent National Cancer Institute guidelines suggest that a minimum of 12 nodes should be examined to ensure accurate staging.
Methods: This population-based study identified stage II (T3N0 and T4N0) CRC cases by using CRC pathology reports (1997-2000) from the Ontario Cancer Registry. Patients aged 19 to 75 years were identified, and demographic, surgical, pathologic, and hospital data were extracted. Factors relating to the number of lymph nodes assessed were examined.
Results: A total of 8848 CRC cases were reviewed, and 1789 stage II cases were identified. Seventy-three percent of cases were designated as node negative on the basis of assessment of <12 lymph nodes. Multivariate analysis showed that age, tumor size, specimen length, use of a pathology template, and academic status of the hospital were significant predictors of the number of lymph nodes assessed.
Conclusions: A subset of patients with CRC in Ontario were assigned stage II disease on the basis of examination of relatively few lymph nodes.