However, by this point, the cancer cells have already divided for 30 generations, and the number of cancer cells has reached a billion. Since cancer cells begin to enter the bloodstream when the tumor is a mere 0.22cm large, and the number of cells is only about 10 million, this means that by the time the tumor is large enough to be detected, the cancer has already begun to spread.
賴基銘指出，腫瘤要一公分以上才能被超音波發現，此刻癌細胞已分裂至三十代，癌細胞數目已達十的九次方，而早在腫瘤零點二二公分大小、癌細胞數在十的七次方左右時，癌細胞已經跑到血液中，換句話說，癌症已經開始轉移、擴散了。