Cervical lymph node metastases from occult squamous cell carcinoma: cut down a tree to get an apple?

To review the value of extended diagnostic work-up procedures and to compare the results of comprehensive or volume-restricted radiotherapy in patients presenting with cervical lymph node metastases from clinically undetectable squamous cell carcinoma.

A systematic review was undertaken of published papers up to May 2000.

Positron emission tomography (PET) has an overall staging accuracy of 69%, with a positive predictive value of 56% and negative predictive value of 86%. With negative routine clinical examination and computerized tomography (CT) or magnetic resonance imaging (MRI), PET detected primary tumors in 5-25% of patients, whereas ipsilateral tonsillectomy discovered carcinoma in about 25% of patients. Laser-induced fluorescence imaging with panendoscopy and directed biopsies showed some encouraging preliminary results and warrants further study. All together, the reported mucosal carcinoma emergence rates were 2-13% (median, 9.5%) after comprehensive radiotherapy and 5-44% (median, 8%) after unilateral neck irradiation. The corresponding nodal relapse rates were 8-45% (median, 19%) and 31-63% (median, 51.5%), and 5-year survival rates were 34-63% (median, 50%) and 22-41% (median, 36.5%), respectively. Retrospective single-institution comparisons between comprehensive and unilateral neck radiotherapy did not show apparent differences in outcome. Prognostic determinants for survival are the N stage, number of nodes, extracapsular extension, and histologic grade. No data were found to support the benefit of chemotherapy in this disease.

Physical examination, CT or MRI, and panendoscopy with biopsies remain the standard work-up for these patients. Routine use of PET or laser-induced fluorescence imaging cannot be firmly advocated based on presently available data. Although combination of nodal dissection with comprehensive radiotherapy yielded most favorable results, its impact on the quality of life should be recognized, and the confounding effects of patient selection for various treatment modalities on therapeutic outcome cannot be ruled out. A randomized trial comparing the therapeutic value of comprehensive vs. volume-limited radiotherapy is being considered.