Incomplete intrapulmonary lymph node retrieval after routine pathologic examination of resected lung cancer

Pathologic nodal stage affects prognosis in patients with surgically resected non-small-cell lung cancer (NSCLC). Unlike examination of mediastinal lymph nodes (LNs), which depends on surgical practice, accurate examination of intrapulmonary (N1) nodes depends primarily on pathology practice. We investigated the completeness of N1 LN examination in NSCLC resection specimens and its potential impact on stage.

We performed a case-control study of a special pathologic examination (SPE) protocol using thin gross dissection with retrieval and microscopic examination of all LN-like material on remnant NSCLC resection specimens after routine pathologic examination (RPE). We compared LNs retrieved by the SPE protocol with nodes examined after RPE of the same lung specimens and with those of an external control cohort.

We retrieved additional LNs in 66 (90%) of 73 patient cases and discovered metastasis in 56 (11%) of 514 retrieved LNs from 27% of all patients. We found unexpected LN metastasis in six (12%) of 50 node-negative patients. Three other patients had undetected satellite metastatic nodules. Pathologic stage was upgraded in eight (11%) of 73 patients. The time required for the SPE protocol decreased significantly with experience, with no change in the number of LNs found.

Standard pathology practice frequently leaves large numbers of N1 LNs unexamined, a clinically significant proportion of which harbor metastasis. By improving N1 LN examination, SPE can have an impact on prognosis and adjuvant management. We suggest adoption of the SPE to improve pathologic staging of resected NSCLC.