Clinicopathological study of invasion patterns and late cervical lymph node metastasis in pT1/T2 oral squamous cell carcinoma

Despite early-stage oral squamous cell carcinoma (OSCC) often being treated effectively with surgery or radiation, 20-40% of patients develop late cervical lymph node metastasis (LCLM), significantly impacting survival rates. This clinicopathological study was performed to investigate the association between invasion patterns and LCLM with pT1/T2 OSCC, treated surgically without preoperative chemotherapy or radiation; 145 patients were included, of whom 21 developed LCLM. Various histopathological factors were analysed, including depth of invasion (DOI), grade, pattern of invasion (POI), and the Yamamoto-Kohama classification. Multivariable analysis revealed that grade and POI were independent prognostic factors for LCLM; higher grade (hazard ratio 3.49, P = 0.043) and POI (hazard ratio 9.35, P = 0.007) were associated with an increased metastasis risk. Notably, 88.9% of cases with worst pattern of invasion-5 (WPOI-5) demonstrated LCLM. The study suggests that a combination of POI and grade should be considered for more accurate prediction and management of the LCLM risk, potentially guiding decisions on elective neck dissection to improve patient outcomes. However, WPOI-5 is difficult to identify from biopsy specimens, highlighting the need for a comprehensive approach combining multiple factors to accurately identify cases with a poor prognosis.