Analysis of unknown primary carcinomas metastatic to the neck: diagnosis, treatment, and outcomes

Metastatic squamous cell carcinoma presenting in the neck from an unknown primary site represetns 2% to 6% of head and neck cancers. Optimal management of these cases remains controversial and continues to evolve with experience. We performed a retrospective analysis involving patients treated for unknown primary squamous cell carcinomas with metastases to cervical lymph nodes who presented to either the University of Kentucky or the Veterans Affairs Hospital of Lexington, Kentucky, from 1990 to 2000. Thirty-five out of 173 patients met inclusion criteria for carcinoma of unknown primary. The following data subsets were analyzed: age, gender, smoking and alcohol use, family history, diagnostic studies performed, radiation dose, surgical intervention, number and location of pathologic nodes, presence or absence of extracapsular extension, time between surgery and radiation, disease-specific and overall survival, response to treatment, emergence of a primary tumor, and duration of follow-up. Overall and disease-specific survivals were analyzed using, the Kaplan-Meier method and the log-rank test was used to assess differences in survival curves. The actuarial 5-year overall and disease-specific survival of all patients in this study was 54% and 63%, respectively. At 10 years, the overall survival declined to 37% with a disease-specific survival rate of 49%. The 5-year survival rates stratified by nodal stage were 80% for N1 patients, 64.7% for N2, 55.6% for N3, and 0% for any M disease. These rates declined to 60% for N1, 52.9% for N2, 11.1% for N3, and 0% for any M disease at 10 years (p<.0001). The presence of extracapsular spread, increased number of positive lymph nodes, and eventual discovery of a primary tumor did not significantly decrease survival in this series. The mean follow-up period for patients in this study was 54.8 months. We continue to refine our diagnostic and treatment strategies in this group of patients in an effort to improve long-term survival and reduce patient morbidity.