Background To examine swallowing-related lower cranial nerve palsy (LCNP) in oropharyngeal cancer (OPC) survivors after intensity modulated radiotherapy (IMRT). Methods Patients treated with definitive IMRT (66–72 Gy) were pooled from trial databases. Prospective analyses on parent trials included videofluoroscopy, clinical LCNP examination, and questionnaires pre- and 6-, 12-, and 24-months post-IMRT. Time-to-event and incidence of LCNP was estimated with competing risk methods. Literature review (1977–2015) summarized published LCNP outcomes. Results Three of 59 OPC survivors with a minimum 2-year follow-up developed hypoglossal palsy ipsilateral to the index tumor (median latency: 6.7 years, range: 4.6–7.6). At a median of 5.7 years, cumulative incidence of LCNP was 5%. LCNP preceded progressive dysphagia in all cases. Published studies found median incidence of radiation-associated LCNP was 10.5% after NPC, but no OPC-specific estimate. Conclusions While uncommon, the potential for late LCNP preceding swallowing deterioration highlights the importance of long-term functional surveillance in OPC survivorship.

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