>> Furthermore, the accuracy of tumor identification has reached 90%.

How is this accuracy calculated? Further in the article it is noted that there is no patient data saved by the project:

>> He said that he’s not sure actually how many people have used it because the data is not saved on the server due to patient privacy concerns. But during that time, he received a lot of thank-you emails from patients, many of them from China.

Considering user privacy is laudable in my opinion, but I'm still curious to know how accuracy is known.