Due to field cancerization, patients with esophageal squamous cell carcinoma (ESCC) have a high risk of synchronous or metachronous head and neck cancer (HNC). Advances in image-enhanced endoscopy and increased awareness among endoscopists have improved detection rates. However, pharyngeal assessment using the transoral Valsalva maneuver often provides insufficient visualization, partly because laryngeal elevation varies widely among individuals. Moreover, anatomical constraints make the tongue base difficult to observe. Since 2025, our institution has introduced systematic pharyngeal observation using a transnasal endoscope (GIF-1200N). For patients scheduled for esophageal ESD who show inadequate pharyngeal visibility despite the transoral Valsalva maneuver, additional preoperative evaluation using a curved laryngoscope is performed in the operating room.

To evaluate the usefulness of transnasal endoscopy for pharyngeal observation by analyzing lesion distribution and diagnostic methods before and after its introduction.

We retrospectively reviewed patients diagnosed with superficial HNC at our department between April 2012 and October 2025. Nineteen patients with 36 lesions were included. The study period was divided into an early phase (2012–2024; 24 lesions) and a late phase (2025; 12 lesions). We compared the methods used at lesion detection, including transoral observation, transoral Valsalva maneuver, transnasal Valsalva maneuver, intra-oropharyngeal U-turn method, and observation using a curved laryngoscope. Endoscope type and lesion location were also evaluated.

ll patients were male, with a median age of 74 (range 59–84) in the early phase and 70 (62–82) in the late phase. Observation methods in the early vs. late phase were: transoral observation (17 vs. 4), transoral Valsalva (7 vs. 0), transnasal Valsalva (0 vs. 4), intra-oropharyngeal U-turn (0 vs. 4), and curved laryngoscope (0 vs. 4). Endoscopes used (H260Z / H290Z / 1200N) were 18/6/0 in the early phase and 4/4/4 in the late phase. Lesion locations in the early vs. late phase were: oral cavity (1 vs. 0), oropharynx (4 vs. 3), hypopharynx (15 vs. 2), post-cricoid region (1 vs. 3), epiglottic vallecula (3 vs. 0), and tongue base (0 vs. 4).

Lesion detection increased in the late phase after the introduction of transnasal endoscopy. Notably, tongue-base cancers were not detected in the early phase, whereas four such lesions were identified in the late phase. Transnasal intra-oropharyngeal U-turn provided excellent visualization of the tongue base, leading to improved detection. Many ESCC/HNC high-risk patients had multiple missing teeth, which often limited laryngeal elevation during the transoral Valsalva maneuver. In contrast, the transnasal Valsalva maneuver is unaffected by dentition and therefore enhances pharyngeal visibility. Nevertheless, laryngeal elevation with the transnasal approach also varied among patients. In cases with insufficient visualization, additional observation using a curved laryngoscope enabled identification of lesions—especially in the post-cricoid area—that had previously been difficult to detect.

In patients at high risk for head and neck cancer, the transnasal Valsalva maneuver and transnasal intra-oropharyngeal U-turn are highly effective for observing the tongue base and post-cricoid region, which are key blind spots during standard transoral endoscopy. For cases with inadequate laryngeal elevation during the Valsalva maneuver, supplementary evaluation using a curved laryngoscope further improves early detection. Introducing a structured transnasal pharyngeal observation protocol may significantly enhance surveillance accuracy in ESCC patients.