Inhibitory effect of neoadjuvant chemotherapy on metastasis of oral squamous cell carcinoma in a mouse model

SummaryThe presence or absence of metastasis bears an important influence on the prognosis of head and neck cancer patients. Neoadjuvant chemotherapy has become widely employed as an initial treatment. However, the actual effectiveness of neoadjuvant chemotherapy on metastasis is still unestablished. Therefore, using an orthotopic implantation model in which cervical lymph node metastasis of oral squamous cell carcinoma can be reproduced, we investigated the inhibitory effect of neoadjuvant chemotherapy on metastasis. A highly invasive and metastatic human oral squamous cell carcinoma cell line, OSC-19 cells, was implanted into the tongues of nude mice. After implantation, the mice were divided into four groups: S (surgery), C + S (preoperative chemotherapy + surgery), S + C (surgery + postoperative chemotherapy), and a control (nontreatment) groups. The treatment (tumor resection or chemotherapy) was started 7 days postimplantation. The effects of each treatment on cervical lymph node metastasis were investigated by examining the rate of lymph node metastasis formation at 28 days postimplantation. In the control group, five of the 11 mice died of cachexia before the end of the experiment. However, all mice in the S, C + S, and S + C groups survived until 28 days after implantation. The cervical lymph node metastasis rates were 81.8% in S, 18.1% in C + S, 63.6% in S + C, and 100% in control groups. Thus, metastasis to the cervical lymph node was markedly inhibited by the combination of neoadjuvant chemotherapy and tumor resection. The findings of this study indicate that neoadjuvant chemotherapy is effective for inhibiting metastasis, and that it is necessary to begin chemotherapy as early as possible to achieve an inhibitory effect on metastasis. Considering these effects, if anticancer drugs are used, better therapeutic results can be expected.