How accurate is pre-treatment, contrast-enhanced CT in diagnosing extracapsular spread (ECS) in cervical lymph node metastases from head-and-neck squamous cell carcinoma (HNSCC)?
Background: ECS has traditionally been a marker of poor disease-specific survival and increased locoregional recurrence among HNSCC patients. ECS presence, along with positive margins, is used to identify patients who will benefit from adjuvant therapy. With the discovery of human papillomavirus (HPV) as a distinct causative agent for a subset of HNSCC patients, the prognostic value of ECS in HPV-positive patients has been reevaluated, and its role is controversial.
Study design: Retrospective observational study of 65 patients diagnosed between February 2004 and March 2013 with p16-positive HNSCC and with cervical lymph node metastases measuring at least 1 cm in diameter on pathological assessment.
Setting: University of Pittsburgh Medical Center; University of Pittsburgh Cancer Institute, Biostatistics Facility, Pennsylvania.
Synopsis: More than half of all patients had histological evidence of ECS. CT accuracy for ECS detection was poor. When observers 1 and 2 rated a patient as having “definite ECS,” they were correct 100% of the time, but there was no evidence of ECS in 38% and 33% of cases rated as having “likely ECS.” When observers 1 and 2 rated patients as “definitely not ECS,” they were correct in 43% and 59% of cases, respectively. Observer 1 did not rate any patient as “equivocal,” while observer 2 rated seven patients as “equivocal”; 86% of those patients were found to have ECS. The positive predictive value of matted nodes was 80% and 100% for observers 1 and 2, respectively. No significant differences in sensitivity and specificity were seen in patients with a single pathologic node versus multiple pathologic nodes. Limitations included a limited cohort of patients, poor feasibility to correlate the specific lymph node on imaging to histology, variability of CT scan quality and interpreting radiologist experience, and potential observer bias.
Bottom line: Unless there is unequivocal invasion of adjacent structures by metastatic lymph nodes, modern multidetector CT is not an accurate method for reliably determining the presence of ECS in p16-positive HNSCC patients.
Citation: Maxwell JH, Rath TJ, Byrd JK, et al. Accuracy of computed tomography to predict extracapsular spread in p16-positive squamous cell carcinoma. Laryngoscope. 2015;125:1613-1618.
—Reviewed by Amy Hamaker