translation.en: But even with the best tools and technologies that we have today, some tumors can't be detected until 10 years after they've started growing, when they are 50 million cancer cells strong.
translation.zh: 但是就算使用如今我们拥有的 最先进的工具和手段， 一些肿瘤仍然无法被探测到， 直到它们已经生长了十年才被发现， 这时已经积累了5000万的癌细胞了。