A total of 28% had not talked about the symptoms, the University of Aberdeen paper revealed.
Lead author Dr Peter Murchie said it highlighted the complications surrounding emergency cancer diagnosis.
Cancer Research UK said it was a complex area.
The study - published in the British Journal of Cancer - said that, of those who had previously flagged symptoms to their doctor, 81% had been appropriately referred on by their GP for further treatment or investigation of their symptoms.
However it said 19% could be viewed as missed opportunities for earlier diagnosis.
The study, funded by the Scottish Chief Scientist's Office, involved a review of the case notes from 1,800 patients diagnosed with cancer in northern Scotland and registered at GP surgeries across NHS Grampian, Orkney and Shetland.
Dr Murchie, a GP and researcher at the University of Aberdeen, said: "This study sheds light on the complications surrounding emergency cancer diagnosis and how quickly circumstances can change for the patient.
"It's vital we do more to ensure people with persistent or unusual symptoms feel confident about getting them checked out by a doctor without delay.
"And it's equally important to give GPs better access to the tests and specialist advice they need to help them spot potential cancer symptoms at the earliest stage."
Jodie Moffat, Cancer Research UK's head of early diagnosis, said: "For some patients, emergency presentation may be difficult to avoid, but for others there are often things that could have been done differently.
"Studies like this help us to understand this complex picture and identify what needs to change.
"Cancer patients diagnosed as an emergency are more likely to have late stage disease and poorer survival. So it's vital we do all we can to break down barriers to people visiting their doctor with symptoms that could be cancer.
"Cancer Research UK is also working with GPs in Scotland to help improve early cancer diagnosis and ensure they have the freedom to refer patients for further tests and access specialist advice if cancer is suspected."
More than a quarter of cancer patients diagnosed as an emergency in the north of Scotland had not discussed any relevant symptoms with their GP beforehand, according to a new study.