Around 35 per cent of cancer patients waited too long to see their doctor about bleeding from their bottom - despite it being a cancer symptom, according to research published in the British Journal of Cancer today.
While more than 90 per cent of people will make an appointment to see a doctor within three months if they have blood in their urine, rectal bleeding was one of the symptoms most often linked to delay.
Worryingly, more than one in five cancer patients waited more than three months before visiting a doctor about their symptoms.
The most common reason for delaying - seen in 27 per cent of all patients - was failing to realise that their symptoms were serious. Embarrassment, or worrying about wasting the doctor's time were also factors that put people off from seeing their GP, but each of these reasons was only reported in less than 6 per cent of patients.
The study also found that delay was much more common among patients living in the most deprived areas.
Dr Lindsay Forbes, co-director of the King's College London Early Presentation Group, said: "This research highlights that we must do more to make sure the public recognises key symptoms of cancer like unexplained pain, unusual bleeding or weight loss, as well as a lump and make sure they get these checked out as soon as possible.
"Although a worrying number of patients across society are waiting too long to go to their doctor, it is those in the most deprived areas that are most likely to delay."
The researchers surveyed 2371 patients with 15 different cancers about the symptoms that had led to diagnosis. There was no difference in the time it took to arrange a GP appointment between men and women or young and old patients.
Patients with prostate cancer and rectal cancer were most likely to delay while breast cancer patients were the least likely.
Sara Hiom, Cancer Research UK's director of early diagnosis, said: "This research highlights how incredibly important it is that everyone is aware of the wide range of cancer symptoms, and has the confidence to tell their doctor. The earlier cancer is diagnosed, the higher the chance of survival and it's essential that people report any symptoms promptly to their GP. No one should be waiting three months before booking an appointment.
"It's important that we continue investing in our work with both the National Health Service and Public Health England on the Be Clear on Cancer campaigns which are successfully raising awareness of these cancer symptoms and encouraging people to see their doctors."
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Forbes et al. "Risk factors for delay in symptomatic presentation: a survey of cancer patients." British Journal of Cancer. 10.1038/bjc.2014.304.