Stage Information for NSCLC
Evaluation of mediastinal lymph node metastasis
Surgical staging of the mediastinum is considered standard if accurate evaluation of the nodal status is needed to determine therapy.
Accurate staging of the mediastinal lymph nodes provides important prognostic information. The association between survival and the number of examined lymph nodes during surgery for patients with stage I NSCLC treated with definitive surgical resection was assessed from the population-based Surveillance, Epidemiology and End Results database for the period from 1990 to 2000. A total of 16,800 patients were included in the study.
The overall survival analysis for patients without radiation therapy demonstrated that in comparison to the reference group (1-4 lymph nodes), patients with five to eight lymph nodes examined during surgery had a modest but statistically significant increase in survival, with a proportionate hazard ratio (HR) of 0.90 (95% confidence interval [CI], 0.84-0.97). For patients with 9 to 12 lymph nodes and 13 to 16 lymph nodes examined, HRs were 0.86 (95% CI, 0.79-0.95) and 0.78 (95% CI, 0.68-0.90), respectively. There appeared to be no incremental improvement after evaluating more than 16 lymph nodes. The corresponding results for lung cancer-specific mortality and for patients receiving radiation therapy were not substantially different.
These results indicate that patient survival following resection for NSCLC is associated with the number of lymph nodes evaluated during surgery. Because this is most likely the result of a reduction of staging error, namely, a decreased likelihood of missing positive lymph nodes with an increasing number of lymph nodes sampled, it suggests that an evaluation of nodal status should include 11 to 16 lymph nodes.
CT scanning is primarily used for determining the size of the tumor. The CT scan should extend inferiorly to include the liver and adrenal glands. MRI scans of the thorax and upper abdomen do not appear to yield advantages over CT scans.
A systematic review of the medical literature relating to the accuracy of CT scanning for noninvasive staging of the mediastinum in patients with lung cancer has been conducted. In the 35 studies published between 1991 and June 2006, 5,111 evaluable patients were identified. The median prevalence of mediastinal metastasis was 28% (range, 18%-56%). Almost all studies specified that CT scanning was performed following the administration of IV contrast material and that a positive test result was defined as the presence of one or more lymph nodes that measured larger than 1 cm on the short-axis diameter. The pooled sensitivity and specificity of CT scanning for identifying mediastinal lymph node metastasis were 51% (95% CI, 47%-54%) and 86% (95% CI, 84%-88%), respectively. The corresponding positive and negative likelihood ratios were 3.4 and 0.6, respectively.