Is it reliable to realize early screening of upper digestive tract tumors by cytological examination of Shikang 1?

Basically, it can be considered unreliable. First of all, the so-called "early cancer screening" is basically the same as the knowledge of students' exams. Originally, due to numerous special reasons and circumstances, there may be great inaccuracies. What's more, the so-called "early screening" is not a "national unified exam" or a "world unified exam" ... just like the exams given by teachers and cats and dogs, it is even less authoritative and has no standards.