Objectives: Margin status evaluation after TORS (transoral robotic surgery) for oropharyngeal carcinoma is challenging due to a lack of standardization regarding a clear vs. positive margin, along with uncertainty on how to account for additional intraoperative margins. Therefore, many pathologists rely solely on the main resected tumor specimen to determine final margin status, with additional margins left for the multi-disciplinary team to interpret. The goals of this study are to describe 1) discrepancies in margin status between the pathology report and multi-disciplinary team; 2) the frequency of changes of the final margin status after multi-disciplinary team discussion; and 3) how patterns of adjuvant therapy are affected by margin status in the post-TORS setting.

Design:Prospective cohort study

Setting: Single tertiary referral center

Patients: All patients diagnosed with squamous cell carcinoma of the oropharynx who underwent TORS from January 2010 to Dec. 31, 2015 were eligible. We excluded those with recurrent disease, < 3 months of follow up after treatment, previous radiation therapy to the head and neck, or unknown primary tumor site.

Main Outcomes Measures: Our main outcome measures were margin status based on the pathology report, margin status based on multi-disciplinary team discussion, and receipt of adjuvant chemotherapy in the post-TORS setting. Margin status determination in the pathology report was based on main specimen analysis. Multi-disciplinary team discussion modified the margin status based additional intraoperative margins and the following criteria: >2mm clear, 1-2mm close and <1 mm positive. For tonsillar carcinoma, the deep margin was dichotomized as either clear or positive.

Results: Sixty-three patients were included. A majority (60/63, 95.2%) underwent a neck dissection or excisional node biopsy before or along with their TORS; of which, 18/60 (30%) had evidence of extra-capsular spread. Radiation therapy was administered to 53/63 (84.1%), with 24/63 (38.0%) also receiving chemotherapy. Based on the pathology report, 32/63 (50.8%) had a positive margin status, yet after multi-disciplinary team discussion, only 3 were considered positive; the remaining 28 were re-classified as clear, and 1 was considered close. When limiting to those without extra-capsular spread (n=43), 2 had positive margins per multi-disciplinary team call, and both received chemotherapy, while 20 had positive margins per pathology report and only 4/20 (20%) received chemotherapy. Margin status determination by pathology report was not associated with receipt of chemotherapy (p = 0.815), while margin  status determination by multi-disciplinary team was (p = 0.0005). With a median follow up time of 26.5 months, the recurrence rate was 4/63 (6.3%), of which 2 already received chemotherapy and 1 was non-compliant. The remaining subject had no extra-capsular spread and clear margins based on pathology report and multi-disciplinary team.

Conclusion: Surgical management with TORS results in a discrepancy between final margin status determination by pathology report vs. the multi-disciplinary team. Pathology margin status evaluation did not correlate with whether the subject received adjuvant chemotherapy, while multi-disciplinary team margin status did. Consideration of additional margins and using the above criteria had a low recurrence rate. Without these, many may have received unnecessary post-operative adjuvant therapy.