How do you know when this guy's stage 1 cancer would become a stage 4 without treatment so that you can line up the data series? Maybe it's stage 1 because you

How do you know when this guy's stage 1 cancer would become a stage 4 without treatment so that you can line up the data series? Maybe it's stage 1 because you got lucky and saw it early. Maybe it's stage 1 because it grows really slowly and will be stage 1 still in 5 years. Only way you could know is to not treat and watch what happens... Everything else is a fudge.