Do routine blood tests detect cancers?

[Zubes]

I felt under the weather around xmas time (glands swollen in neck, tiredness/weakness) so I had two routine blood tests done (December 2020 and February 2021) and both came back normal - All organs were functioning normally.
Do routine blood tests show up cancers, such as Leukaemia? I know you're not doctors on here, but I feel a bit silly phoning the doctor to ask this when my results came back ok. Thanks.

Yes your blood would show a higher white cell count which would indicate something going on on the body and doctors would likely investigate further. Try not worry. How is your diet/ weight etc? Do you exercise? May be a lifestyle change would improve tiredness etc.

Yes. It wouldn’t necessarily diagnose leukaemia but it would flag an issue that required further tests.