Head and Neck Cancer

PV QA 2 - Poster Viewing Q&A 2

MO_26_2632 - Should Depth of Invasion Determine the Need for Postoperative Radiation Therapy in Early-Stage Oral Tongue Cancer

Monday, October 22
10:45 AM - 12:15 PM
Location: Innovation Hub, Exhibit Hall 3

Should Depth of Invasion Determine the Need for Postoperative Radiation Therapy in Early-Stage Oral Tongue Cancer
J. M. Mann, D. A. Julie, S. Mahase, D. D'Angelo, A. G. Wernicke, and B. Parashar; New York Presbyterian Hospital/Weill Cornell Medicine, New York, NY

Purpose/Objective(s): In early-stage, node negative oral tongue cancer, there is limited data supporting the role of tumor depth of invasion (DOI) as an indication for post-operative radiotherapy (PORT) to the primary site. There is a general consensus that greater DOI confers an increased risk of regional recurrence and worse survival outcomes. Furthermore, the 8th edition of the American Joint Committee on Cancer (AJCC) staging introduced DOI into the T category. The primary aim of this study is to examine the effect of tumor DOI and PORT on overall survival (OS).

Materials/Methods: The National Cancer Database (NCDB) was used to query patients with AJCC stage I and II oral tongue cancer diagnosed between 2006 and 2013. Patients were stratified by receipt of PORT, elective neck dissection, and extent of tumor DOI (≤4 mm or >4 mm). Kaplan-Meier analysis was performed to compare OS (using the log-rank test) between patients receiving and not receiving PORT. Multivariable Cox proportional hazards regression model was used to evaluate the independent effect of PORT on OS, while controlling for tumor DOI and other clinical characteristics.

Results: Among 939 patients with oral tongue cancer, 69.3% were clinical Stage I, 67.4% received elective neck dissection, 23.4% had tumor DOI >4 mm, and 10.4% received PORT. The addition of PORT did not improve OS for patients with tumor DOI ≤4 mm (p=0.634) or >4 mm (p=0.816). The addition of elective neck dissection improved OS for DOI >4 mm (p=0.010), but not for ≤4 mm (p=0.128). On multivariable survival analysis, elective neck dissection remained associated with improved OS in the subset of patients with DOI >4 mm (hazard ratio of death, 0.37; 95% confidence interval, 0.17-0.81 [p=.012]), when also controlling for age, sex, PORT status, clinical stage, and pathological stage.

Conclusion: Tumor DOI should not be used alone as consideration for PORT to the primary site following surgical management of early-stage oral tongue cancer. Traditional tumor characteristics such as positive or close margins, perineural invasion, lymphovascular invasion, and T3-T4 disease should continue to be used as standard indications for PORT to the primary site. Elective neck dissection at the time of excision of the primary tumor results in higher OS for tumors with DOI >4 mm.

Author Disclosure: J.M. Mann: None. D.A. Julie: None. D. D'Angelo: None. B. Parashar: Program Director; NYHQ/NYP.

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