detecting type of cancer, HUGE if it can displace need for initial biopsy in at least a few types.
real life occurance: to establish if a patient with stage 4 and a lung cancer mass adjacent to the heart and its blood vessels was suited for a certain drug took over 3 hours of life threatening pinpoint biopsy work (2 attempts with patient's escalating reaction) to extract two small samples which then took several days to grow before the lab had a mass large enough to test. EXPENSIVE AND TIME DELAY.
So it was six days before the patient knew she had a chance to be successfully treated (it was the only sub type, at 12% of all lung cancers, best treated with one specific drug -- for a 18 months survival chance versus six to eight weeks to death otherwise).