Site, size, and tumour involvement of resected extrapulmonary lymph nodes in lung cancer

A prospective study was performed analyzing resected extrapulmonary lymph nodes of 544 operated lung carcinoma patients. Volume of lymph nodes was determined by weight. Lymph nodes were cut in serial sections 300 microns thick, and the volume of tumour metastasis in each resected lymph node was computed measuring the tumourous area in the lymph node sections. The following results were obtained: Percentage of resected lymph nodes varied with lymph node site and site of the primary lung cancer. Hilar lymph nodes were resected in 50% of the patients, lymph nodes of the main and stem bronchi in 57% and 63%, respectively. Tumour metastases were found in 10%-15% of the resected lymph nodes. The size of the lymph nodes varied to a large amount and was found to be independent of the lymph node site if no metastases could be detected. Lymph nodes measuring less than 0.1 ccm were tumour infiltrated in 9% (77/706 lymph nodes), large lymph nodes (greater than 10 ccm) in 62% of the cases (20/32). Tumourous involved lymph nodes of the main bronchus were found more frequently in cases of central localized lung cancer compared to carcinoma arising from the peripheral lung, where the opposite was seen in subaortal located lymph nodes. The percentage of lymph node involvement and size of tumour infiltrated lymph nodes was found to be independent of tumour cell type. Size of resected lymph nodes is not a reliable parameter for estimating existence of tumour infiltrations.