Perineural invasion in squamous cell carcinoma of the head and neck.

To determine if perineural invasion (PNI) of small nerves affects the outcome of patients with squamous cell carcinoma (SCC) of the upper aerodigestive tract. Retrospective clinicopathological study of patients with at least 2 years of follow-up and with negative margins and no prior, synchronous, or metachronous SCC. Academic otolaryngology department. One hundred forty-two patients who had SCC of the oral cavity, oropharynx and hypopharynx, or larynx resected between 1981 and 1991. Surgery with or without adjuvant therapy. Local recurrence was examined with respect to PNI, nerve diameter, and microvascular or microlymphatic invasion. Perineural invasion was correlated with lymph node metastasis, extracapsular spread, and survival. Perineural invasion of nerves less than 1 mm in diameter was present in 74 patients, lymphatic invasion in 53, and vascular invasion in 9. Perineural invasion was significantly associated with local recurrence (23% for PNI vs 9% for no PNI; P=. 02), and disease-specific mortality (54% mortality for PNI vs 25% for no PNI; P<.001). With extralaryngeal tumors, PNI was associated with nodal metastasis (73% vs 46%; P=.03). Perineural invasion was not associated with extracapsular spread (P=.47). Microvascular invasion, lymphatic invasion, and nerve diameter were not significantly related to local recurrence. Perineural invasion of small nerves is associated with an increased risk of local recurrence and cervical metastasis and is, independent of extracapsular spread, a predictor of survival for patients with SCC of the upper aerodigestive tract.