The epidemiological and histopathological factors for delayed local recurrence in oral squamous cell carcinoma.

Background: Oral squamous cell carcinoma (OSCC) is a prevalent malignancy in oral cancer. Approximately 26% of OSCC cases recur after initial curative treatment, with over 80% of these recurrences occurring within the first 2 years. Delayed local recurrence (DLR) occurring beyond the 2-year period in cases of OSCC is infrequent. The aim of this study is to investigate the histopathological characteristics associated with DLR.

Methods: This study included 197 patients diagnosed with OSCC who underwent primary surgery from 2006 to 2022. Epidemiological features, such as age and gender, and histopathological features, including primary tumor sites, TNM staging, histopathological grading, depth of invasion, the presence of lymphovascular or perineural invasion, and the utilization of radiation therapy (RT) and neck dissection (ND) were analyzed.

Results: The mean interval until local recurrence was 22 ± 27 months. There were 10 cases of DLR (20.83%) among 51 patients with local recurrence. The epidemiological and histopathological analysis of these cases is as follows: 10 patients (3 males and 7 females) aged 51-80 years (median, 56.5 years). Primary tumor sites were tongue (n = 3), maxillary gingiva (n = 1), mandibular gingiva (n = 3), retromolar trigone (n = 1), and buccal mucosa (n = 2). Tumor size was advanced (T3/T4) in 5 cases, while a smaller size (T1/T2) was observed in 5 cases. No lymph node metastasis was 80.0%. Histopathological grading was well differentiated in 9 cases and moderately differentiated in 1 case, with no cases of poorly differentiated tumors. Depth of invasion > 5 mm was 70.0% of the cases (n = 7). Lymphovascular invasion and perineural invasion were not present. Three patients received RT, and 8 patients underwent ND. There were 2 patients who consumed alcohol, and 2 patients who smoked tobacco. The results showed that histological differentiation had a significant relationship with the interval (p = 0.031).

Conclusions: DLR, occurring more than 2 years after the initial tumor resection surgery, is infrequent. Histological differentiation is associated with tumor recurrence intervals. Patients with a higher histological grading require more precise follow-up observation during the initial 2 years after surgery.