Jennifer Lobo Shah MD, Presenter: Nothing to Disclose

Wendy Hara MD, Abstract Co-Author: Nothing to Disclose

Standard treatment for oral cavity squamous cell carcinoma (OCSCC) is surgical resection followed by adjuvant therapy based on pathologic analysis. Pre-operative imaging has been used to determine nodal involvement and has guided determination of the need for a neck dissection (ND). We sought to evaluate the patterns of failure when a ND was omitted due to pre-operative PET/CT showing no nodal involvement.

From 2003-2013, we treated 761 patients with OCSCC. A pre-operative PET/CT was performed for 333 patients, of which 260 were retrospectively reviewed. ND was omitted in 41 of these patients, which comprised the cohort for this analysis. Factors analyzed included demographics, imaging and pathologic data, treatment with adjuvant radiotherapy (RT), and patterns of failure. The Kaplan-Meier rates of local recurrence (LR), regional recurrence (RR), and overall survival (OS) were calculated.

Median follow-up was 37 months. Subsites included: 59% oral tongue, 22% alveolar ridge, 15% floor of mouth, 2% lip, 2% buccal mucosa, 2% retromolar trigone, and 0% hard palate. 41% were T1, 39% were T2, 12% were T3, and 7% were T4. ND was omitted due to a node-negative (NN) PET/CT in 44% or due to perineural invasion (PNI) seen at biopsy indicating a need for adjuvant RT in 29%. Other reasons included co-morbidities and the potential for complications. 46% of patients received adjuvant RT. At median follow-up, OS was 80%, LR was 20%, and RR was 22%. LR was associated with tumor size >2.5 cm (p=0.02) and close margins (p=0.06). Decreased OS was associated with tumor size >2.5 cm (p=0.01), close margins (p=0.06), and node-positive (NP) PET/CT (p=0.01). Of the 12 patients who had a NP PET/CT, the reason for ND omission was PNI in 6 patients, early stage disease in 1 patient, potential complications in 3 patients, and unclear reasons in 2 patients. 33% of the RRs occurred in patients with a NP PET/CT.

This data shows a significant risk of RR in patients with OCSCC with ND omission on the basis of a NN PET/CT. Furthermore, decreased OS was seen in patients with a NP PET/CT with ND omission on the basis of meeting pathologic indications for adjuvant RT. This suggests that ND may play an important therapeutic role in the management of patients with OCSCC irrespective of PET/CT findings.

PET/CT should be used with caution when determining the need for neck dissection in OCSCC .

Shah, J, Hara, W, The Role of PET/CT in the Nodal Management of Squamous Cell Carcinoma of the Oral Cavity.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14016712.html