There are some cancers where blood biomarkers give us more information than others, but save for leukemia, I'm unaware of any that are sufficient for diagnosis.

There are some cancers where blood biomarkers give us more information than others, but save for leukemia, I'm unaware of any that are sufficient for diagnosis. While still widely, the effectiveness of some blood biomarkers like PSA (prostate cancer) can be controversial. So, while I could be wrong since this isn't my area of expertise, there's a long way to go for most cancers when it comes to blood testing.