Public Health England says people with the disease stand a much slimmer chance of surviving when their diagnosis comes via an emergency admission, compared to other routes.
Cancer Research UK says people with unusual or persistent symptoms should be able to seek early help more easily.
In 2018, 772 patients were admitted to hospital with cancer in the NHS Scarborough and Ryedale CCG area, the latest Public Health England data shows.
Of them, 146 (19%) were admitted as an emergency, rather than through routes such as screening programmes or routine GP referrals.
Patients diagnosed in this way are more likely to have more advanced and difficult to treat cancers.
Dr Jodie Moffat, head of early diagnosis at Cancer Research UK, said GPs have made huge efforts to improve early diagnosis by referring more people with suspected cancer symptoms to be seen at hospital within two weeks.
“But significant numbers of people still continue to be diagnosed with cancer after they’ve turned up at A&E,” she added.
“The reasons for this are complex, but encouraging people to seek help early for unusual or persistent symptoms, and reducing any barriers to seeking help, might help to bring this number down.”
Across England, around 19% of cancer patients admitted to hospital arrived as an emergency case last year.
The rate has been falling since 2010, when it stood at 22%.
A spokesperson for Cancer Research UK said a rise in admissions for cancer – which increased 16% over nine years – is largely down to a growing and ageing population.
Lucy Elliss-Brookes, head of cancer analysis at PHE, said: “Patients with cancer presenting as an emergency have significantly worse survival rates, so it is encouraging to see these figures continuing to fall.
“However, we know there is variation across England and that some people are still waiting too long to go and see their GP with symptoms that could suggest cancer.”