Purpose: To investigate the rate and risk factors of contralateral nodal disease in patients with HPV-related base of tongue (BOT) oropharyngeal squamous cell carcinoma (OPSCC).
Methods: Patients with HPV-related BOT OPSCC who underwent primary surgical treatment with transoral surgery and concomitant neck dissection from 1997-2016 at Washington University in St. Louis. All patients had either unilateral or bilateral neck dissections performed. Clinical and pathologic data was collected from patient charts. Institutional practice is to favor dissection of the contralateral nodal basin in patients with no clinical evidence of contralateral nodal disease. If patient remains pathologically free of disease in the contralateral neck, radiation was spare to that nodal basin.
Results: One hundred sixty-two patients were identified. 89 (55%) were male and 73 (45%) were female with a mean age of 58 ± 8 years. 83% had no recurrence, 8% had local recurrence, 6% had regional recurrence, and 6% had distant recurrence. Of those with follow-up greater than 12 months and a median follow-up of 62 months, 54 (36%) bilateral neck dissections. Of these, 37 patients had no clinical contralateral nodal disease. Of patients who had no clinical nodal disease in their contralateral neck, 9 (24%) had pathologic nodal disease. Of those whose tumors did and did not cross midline, pathologic contralateral nodes were present in 63% and 35% respectively. Within the subset of those with no clinical disease in their contralateral neck, occult contralateral nodes were present in 33% and 21% of tumors that did and did not cross midline, respectively. Pathologic and clinical T stage, smoking, lateralization of tumor, and presence of ipsilateral clinical nodal disease were not associated with contralateral occult neck disease. In patients with occult neck disease, there were no regional recurrences if treated with elective neck dissection and adjuvant radiation if pathologic nodes were discovered. In patients with contralateral neck dissection and no occult nodes identified, there were no recurrences when the contralateral nodal basin was spared adjuvant radiation therapy.
Conclusion: Among patients with HPV+ BOT OPSCC, the rate of contralateral nodal disease was 48% overall with a 24% rate of occult nodal disease. Given the rate of and lack of risk factors identified for occult contralateral disease, contralateral neck dissection is recommended in this population if treated with primary surgery. With this approach, we had no regional failures if the contralateral nodal basin was spared adjuvant radiation when it remained free of occult nodal disease and no failures when the contralateral nodal basin received adjuvant radiation if occult nodal disease was identified.