RESUMEN
PURPOSE To provide evidence for the relationship between degree of invasion and tumor metastasis. The tumor cells of transplantable mouse histiocytic sarcoma (L1) were inoculated at the right hind footpads of inbred 615-strain mice. METHODS Once bearing the tumor, all the mice were sacrificed respectively on the 1st. 3th, 5th. 10th, 20th, 30th, and 40th day as to observe the degree of tumor invasion and the process of tumor metastasis. RESULTS When the degree of tumor invasion was grade Ⅲ or Ⅳ , the metastasis of tumor cells was found earliest in draining lymph nodes. However, the tumor metastasis in lung appeared later than in lymph nodes. CONCLUSION According to the time of tumor growth and degree of invasion and metastasis, the authors suggest a new classification for cancer staging, namely, latent, invasive and metastatic stages. During the stage of tumor invasion, it is redivided into early, middle and late invasive phases. During the stage of tumor metastasis, it is redivided into early, middle and late metastatic phases.