Introduction

The local control rate of oral squamous cell carcinoma (OSCC) has recently improved due to the development of various treatment modalities, but patients who suffer regional or distant metastasis still have a poor prognosis. Many authors have reported that nodal involvement is one of the most significant prognostic factors in OSCC and that patients with multiple lymph node metastases have an extremely poor prognosis. Radiotherapy (RT) or concurrent chemoradiotherapy (CCRT) is recommended as a postoperative adjuvant therapy for head and neck squamous cell carcinoma (HNSCC) patients with nodal metastasis. However, the effects of such adjuvant therapies on OSCC are still unclear because of the relatively small number of patients examined in previous studies. Only a few studies of OSCC have examined the number of positive lymph nodes as a prognostic factor, and the optimum threshold number of positive nodes for determining the indications for adjuvant therapy is disputed. Furthermore, the use of postoperative RT or CCRT is associated with various adverse events and a reduction in the treatment options for recurrence. Hence, there are no agreed criteria for the use of postoperative adjuvant therapy.

The aim of this retrospective study was to investigate the relationship between the number of positive lymph nodes and the prognosis in OSCC patients with nodal metastasis, and to assess the effects of postoperative RT and CCRT on this patient group.

Materials and methods

A retrospective investigation of 98 OSCC patients who underwent modified radical neck dissection (levels I–V) at any of five participating hospitals between 2001 and 2010, and who had at least 3 pathologically positive lymph nodes, was performed. In most patients, the internal jugular vein and spinal accessory nerve were preserved, but the sternocleidomastoid muscle was resected. The timing of neck dissection was categorized as follows: immediate neck dissection; i.e., dissection was performed as an initial therapy during the resectioning of the primary tumor; secondary neck dissection, which was performed in patients who were initially staged as N0 but progressed to N+ during the observation period; and neck dissection with local recurrence; i.e., patients who were initially staged as N0, but subsequently developed nodal metastasis and local recurrence. Some patients underwent postoperative RT (total 60–70 Gy) or CCRT (RT plus 70–100 mg/m ² of cisplatin, 60 mg/m ² of docetaxel, or any dose of 5-fluorouracil) ( Fig. 1 ). No indications or regimen for RT or CCRT were established, therefore the decision to use such therapies was made by each institution. The major inclusion criteria were advanced clinical stage, multiple cervical metastases, extranodular invasion (ENI), or a positive resection margin. The major exclusion criteria were old age, a past history of renal failure and hepatitis, and poor performance status. Most patients were examined each month and underwent computed tomography, magnetic resonance imaging, or ultrasonography every 3 months to check their postoperative status.

Chemotherapy regimen and radiotherapy dose (Gy).

The major variables evaluated were clinical and pathological T stage, N stage, the number of pathologically positive lymph nodes, ENI, and the type of treatment received (surgery alone (including postoperative chemotherapy alone), postoperative RT, or postoperative CCRT). The major endpoints evaluated included the disease-free survival rate, loco-regional control rate, and type of recurrence. The Kaplan–Meier method was used to draw survival and loco-regional control curves. Statistical analyses were performed with the log rank test and Fisher’s exact test. A multivariate analysis aimed at elucidating prognostic factors for OSCC was performed using Cox regression analysis.

Materials and methods

A retrospective investigation of 98 OSCC patients who underwent modified radical neck dissection (levels I–V) at any of five participating hospitals between 2001 and 2010, and who had at least 3 pathologically positive lymph nodes, was performed. In most patients, the internal jugular vein and spinal accessory nerve were preserved, but the sternocleidomastoid muscle was resected. The timing of neck dissection was categorized as follows: immediate neck dissection; i.e., dissection was performed as an initial therapy during the resectioning of the primary tumor; secondary neck dissection, which was performed in patients who were initially staged as N0 but progressed to N+ during the observation period; and neck dissection with local recurrence; i.e., patients who were initially staged as N0, but subsequently developed nodal metastasis and local recurrence. Some patients underwent postoperative RT (total 60–70 Gy) or CCRT (RT plus 70–100 mg/m ² of cisplatin, 60 mg/m ² of docetaxel, or any dose of 5-fluorouracil) ( Fig. 1 ). No indications or regimen for RT or CCRT were established, therefore the decision to use such therapies was made by each institution. The major inclusion criteria were advanced clinical stage, multiple cervical metastases, extranodular invasion (ENI), or a positive resection margin. The major exclusion criteria were old age, a past history of renal failure and hepatitis, and poor performance status. Most patients were examined each month and underwent computed tomography, magnetic resonance imaging, or ultrasonography every 3 months to check their postoperative status.

Chemotherapy regimen and radiotherapy dose (Gy).

The major variables evaluated were clinical and pathological T stage, N stage, the number of pathologically positive lymph nodes, ENI, and the type of treatment received (surgery alone (including postoperative chemotherapy alone), postoperative RT, or postoperative CCRT). The major endpoints evaluated included the disease-free survival rate, loco-regional control rate, and type of recurrence. The Kaplan–Meier method was used to draw survival and loco-regional control curves. Statistical analyses were performed with the log rank test and Fisher’s exact test. A multivariate analysis aimed at elucidating prognostic factors for OSCC was performed using Cox regression analysis.

Results