Disparity in pathologic and clinical lymph node staging in oral tongue carcinoma: Implications for therapeutic decision making

BACKGROUND. Regional lymph node metastasis is the most reliable predictor of treatment outcomes for patients with squamous cell carcinoma of the oral tongue (SCCOT). A recent American Joint Committee on Cancer staging update of malignant melanoma has incorporated pathologic lymph node staging. The authors hypothesized that pathologic lymph node staging (pN) would be a more reliable predictor of treatment outcomes than clinical lymph node staging (cN). METHODS. The authors retrospectively reviewed 266 patients who received primary surgical treatment for SCCOT, including a neck dissection, from January 1980 to December 1995. Overall and disease-specific survival and disease-free interval were compared with respect to clinical and pathologic lymph node stages. RESULTS. Statistically significant survival differences were identified for both clinical (cN0-cN2) and pathologic lymph node stages (pN0-pN2). However, survival and disease-free interval differences for pathologic lymph node staging reached higher statistical significance (P < 0.0001) than for clinical lymph node staging (P < 0.002). This disparity can be explained by stage migration (i.e., patients with cN0-1 disease have a more advanced lymph node stage at the time of pathologic review compared with patients without cN0-1 disease). The authors found a 34% rate of occult lymph node disease in the cN0 group (19% of occult lymph nodes had extracapsular spread [ECS]). Similarly, 43% of cN1 patients had a higher stage than pN2b disease and 50% had ECS. CONCLUSIONS. Pathologic lymph node staging, based on a staging or therapeutic neck dissection, should be considered for patients treated for SCCOT to identify high-risk patients who may benefit from additional adjuvant therapy. Prospective studies are essential to validate these findings before pathologic lymph node staging is included in standard staging criteria.