Effect of thermotherapy on metastatic cervical lymphnode of oral cancer

将VX2肿瘤细胞移植到大白兔口腔底，形成颈部淋巴结转移。热疗采用THERMOTRON-RF8进行。5例患者热疗均未能控制原发部位，随访结束时组织病理学检查显示因热疗不完全而局部复发。热疗后的功率多普勒US图像显示，原发部位内血流消失；然而，在周围检测到残余灌注。因此，外周残余血流可能是由于原发部位控制失败所致。在预防淋巴结转移方面，热疗的有效性仍然值得怀疑。在淋巴结转移过程中，先血管增多，后出现无血管区，并逐渐变大，表现为淋巴结内无信号。如果转移灶大到可以检测到无血管区，则热疗不能控制转移灶。如果肿瘤沉积物不像无血管区那么大而无法检测到，则在一些淋巴结中活的肿瘤细胞完全消失。在这些淋巴结中，热疗后短暂的丰富血管减少。其他淋巴结在热疗后仍保持丰富的血管，不能被热疗控制。因此，在显微转移中，功率多普勒图像显示所描绘的血管消失表明热疗法成功。我们认为模型动物的固定和三维热分布的评估是热疗成功的关键。

VX2 tumor cells were transplanted in oral floor of the white rabbits to develop the cervical lymph node metastasis. The thermotherapy was performed by using THERMOTRON-RF8.The thermo therapy failed to control the primary site in all 5 cases, and histopathologic assessment at the end of the follow-up period revealed local relapses due to incomplete thermo therapy. On Power Doppler US image obtained after thermotherapy, the internal blood flow disappeared within the primary site ; however, the residual perfusion was detected at periphery. Therefore, the residual blood flow at periphery might be attributed to the failure of the control of the primary site.In regard to the prevention of lymph node metastasis, the effectiveness of thermo therapy was still questionable. In the process of the lymph node metastasis, the vascularity increased at first, and later, the avasular area appeared and it became larger to be depicted as no signal within lymph node.If the metastasis was large enough to be detected as avascular area, the thermotherapy could not control the metastasis.If the tumor deposit was not so large to be detected as avascular area, viable tumor cells were completely disappeared in some nodes. In such nodes, the transient rich vascularity decreased after thermotherapy. The other nodes retained rich vascularity after thermotherapy and such nodes could not be controlled by thermotherapy. Therefore, in the microscopic metastasis, the disappearance of the depicted vessels obtained by power Doppler images was indicative of success of the thermotherapy.We think that the fixation of model animals and the evaluation of the three-dimensional thermal distribution are essential for success of the thermotherapy.