Cervical nodal metastasis of squamous cell carcinoma of unknown origin: indications for withholding radiation therapy.

The records of patients with pathologically confirmed metastatic squamous cell carcinoma involving cervical lymph nodes who were treated at the Mayo Clinic between January 1965 and December 1987 were reviewed. In 117 patients a primary tumor could not be discovered. Of these, 24 patients underwent curative resection of all gross disease by neck dissection or excisional biopsy. All 24 patients presented with unilateral adenopathy. Their median age was 63 years. Eighteen patients were men. Fourteen patients were in clinical stage N1; six, N2a; three, N2b; and one, N3. Six patients had grade 1 or 2 nodal metastases; 14, grade 3; and 4, grade 4. Gross or microscopic evidence of extracapsular tumor extension was noted in eight patients. All patients were followed until death or for a median of 8.5 years (range, 3.3-20.4 years). A squamous cell carcinoma of the upper aerodigestive tract subsequently developed in only one patient (4%) within 5 years of operation. In six patients (25%), a recurrence developed in the dissected neck a median of 3 months (2.4 months-6.6 years) after operation. Five of these patients had extracapsular extension, and four had pathologic Stage N2a or higher neck disease. Both patients with pathologic Stage N1 disease who had recurrences in the dissected neck had extracapsular extension. Delayed, contralateral neck metastases in an undissected neck developed in two patients. The 5-year overall and cause-specific survivals for all 24 patients were 66% and 74%, respectively. Extracapsular extension was a predictor of neck recurrence, control of disease above the clavicles, cause-specific survival, and overall survival. Patients with pathologic Stage N1 neck disease with no extracapsular extension can be managed by surgery alone. Patients with pathologic Stage N2 or higher neck disease or extracapsular extension should be considered for postoperative, adjuvant radiation therapy.