One in five people in Northern Ireland receive their cancer diagnosis while attending an emergency department (ED), according to research by the NI Cancer Registry.
The registry confirmed to BBC News NI that, at present, a quarter of bowel cancers are being diagnosed in EDs.
It said mostly older patients are affected.
Its research also found that a third of lung cancers in NI are diagnosed after a patient turns up at an ED.
The problem is a direct result of some people waiting too long on hospital lists and being brought to emergency departments instead.
Survival rate ‘lowest’
The head of services at Macmillan Cancer Support, Heather Monteverde, said the statistics were “shocking and extremely worrying”.
She said emergency departments cannot provide the very specialist care needed by cancer