Assessment and clinical significance of micrometastases in lymph nodes of head and neck cancer patients detected by E48 (Ly-6D) quantitative reverse transcription-polymerase chain reaction

The presence of lymph node metastases is the major determinant for prognosis in head and neck squamous cell carcinoma (HNSCC). It is at present unknown whether the same holds true for the presence of histologically undetectable micrometastases. We analyzed 456 histologically tumor-negative lymph nodes of 23 HNSCC patients without (pN0) and 18 patients with one or two tumor-positive lymph nodes (pN+) in their neck dissection specimens at histopathologic examination. To detect the presence of disseminated tumor cells and micrometastases in these lymph nodes, we used real-time quantitative RT-PCR with E48 (Ly-6D) transcripts as a squamous cell-specific molecular marker. The results were compared with histopathologic examination and clinical outcome. E48 transcripts were detected in lymph nodes of 5 (22%) of 23 patients in the pN0 group, and in histologically negative lymph nodes of 10 (56%) of 18 patients in the pN+ group. In the pN0 group, the presence of E48-positive lymph nodes was significantly associated with a distinctly poor cause-specific survival as compared with those with E48-negative lymph nodes. Our results indicate that E48 real-time quantitative RT-PCR is a suitable method for the detection of micrometastases in lymph nodes of patients with HNSCC. Moreover, detection of micrometastases seems clinically relevant but should be confirmed in a large multicenter trial.