The correlation between tumor size and lymphatic vessel invasion in resected peripheral stage I non-small-cell lung cancer. A potential risk of limited resection.

We attempted to clarify whether a correlation exists between tumor size and the incidence of lymphatic vessel invasion in peripheral non-small-cell lung cancer without regional lymph node metastasis. The study included 212 resected non-small-cell lung cancers classified as pathologic stage I disease and located on the periphery of the lung. The incidence of lymphatic vessel invasion was relatively correlated with the maximum diameter of the tumor as follows: 25% (1/4) for tumor size 1.0 cm or less, 40% (19/48) for size 1.1 to 2.0 cm, 49% (28/58) for size 2.1 to 3.0 cm, and 57% (58/102) for tumor size 3.1 cm or more. The incidence of lymphatic vessel invasion of tumors measuring 3 cm or less in greatest dimension was 44% (48/110). The degree of lymphatic vessel invasion of 20 resected tumor samples measuring 3 cm or less in greatest diameter with hilar lymph node metastasis was also examined for comparison. This figure was as high as 85%. These observations suggest that even small peripheral tumors without any regional lymph node metastasis have a relatively high rate of lymphatic vessel invasion and thus pose a potential risk of local recurrence after a limited resection, especially in a wedge resection of the tumor.