Patients and methods

The authors retrospectively reviewed records for 187 patients who underwent radical surgery for OSCC between January 2001 and December 2010. The study cohort included patients with histologically confirmed diagnoses of OSCC and a minimum follow-up of 12 months. All study patients underwent extensive pretreatment evaluations, including blood chemistry, complete blood cell count, chest X-ray, computed tomography (CT) and/or magnetic resonance imaging (MRI) of the head and neck area, thoracoabdominal CT, and provided informed consent to participate in the study. Data collected included demographic information, site, TNM stage at diagnosis, tumour histologic grade, pattern of tumour invasion, treatment, status of the margin, recurrence, and the adjuvant therapy used for disease control.

Tumour stage was classified according to the TNM classification of the International Union against Cancer. Tumour histologic grade was defined according to the WHO classification. All pathological assessments were performed by two expert pathologists (SF and TI) who were unaware of the clinical outcomes. Pattern of invasion (POI) was examined at the host/tumour interface. POI types 1 through 4 have been previously defined by Bryne et al. POI type 1 represents tumour invasion in a broad pushing manner with a smooth outline. POI type 2 represents tumour invasion with broad pushing ‘fingers’ or separate large tumour islands, with a stellate appearance. POI type 3 represents invasive islands of tumour greater than 15 cells/island. POI type 4 represents invasive tumour islands smaller than 15 cells/island. This includes cord-like and single cell invasion. These evaluations were performed using biopsy specimens.

In the authors’ institute, surgery alone is preferred for the treatment of patients with oral cancer. Patients who hesitated in accepting surgical intervention or who did not have surgery available because of a busy schedule were selected for neoadjuvant chemotherapy (NAC). During the period of NAC, patients were encouraged to undergo surgery after completion of chemotherapy. All patients who received NAC underwent radical surgery. The regimen of NAC consisted of a combination of cisplatin-based multi drugs. In most patients, modifications in chemotherapy dosages were made for toxicity as indicated using standard criteria.

Primary tumours were excised with ≥1.5 cm safety margins (both superficial and deep margins). The extent of surgery was not modified according to tumour response with NAC. Surgery included removal of primary tumour and radical neck dissection was performed in patients who had clinically positive cervical lymph node metastasis. Elective neck dissection was not performed routinely. Postoperative adjuvant radiotherapy with a dose field of 60 Gy was given to patients with involved margins or extra-capsular lymph node spread. Local recurrence was defined as lesions arising in the oral cavity relative to primary tumour beyond 6 weeks within the first 5 years after the first definitive treatment. Locoregional recurrence arising in both the primary site and neck was also considered to be local recurrence. Recurrence arising only in the neck was defined as regional recurrence. Patients with recurrences that were considered potentially curable and operable underwent salvage surgery and radiotherapy. Patients with recurrences that were considered incurable were treated with palliative chemotherapy.

For pathological examination of the surgical margin, all permanent section histological slides of primary resection specimens were reviewed retrospectively. Regarding surgical margin distance, a large cohort study demonstrated that the pathological margin distance ≤4 mm was significantly associated with locoregional recurrence. In this study, the status of the surgical margin was classified as >4 and ≤4 mm in the superficial or deep margin, respectively.

Results

Patient characteristics are summarized in Table 1 . The male to female ratio was 1.2 with 102 male subjects. The mean age at diagnosis was 67.3 years (range 28–95 years). The most common primary site was the tongue (73/187 patients, 39.0%); 23.5% of patients had lower gingival cancer and 19.3% had upper gingival cancer.

The local recurrence rate was 16.0% (30/187 patients) during the follow-up period. The mean follow-up period was 36.7 months for the whole series (range 10–125 months). The mean period that elapsed before recurrence was 10.6 months (range 1–48 months), with most recurrences (21/30 patients, 70.0%) occurring during the first year after treatment (90% before 2 years). Site distribution of local recurrence cases was: 8 tongue (11.0%), 3 oral floor (11.5%), 8 upper gingiva (22.2%), 9 lower gingiva (20.5%), and 2 buccal mucosa (25.0%).