Will a er doctor tell you if you have cancer?

Difficult: The definitive diagnosis of cancer requires a biopsy and formal pathology review which can take days to be completed. Therefore it would be very difficult for an emergency room physician to make a definitive diagnosis and communicate it at the time of a single visit.

Depends: Depends on the situation but an er physician can tell you if warranted. If you suspect you have cancer, i would recommend starting with your primary care physician for a workup, who can then direct you to the correct specialists.