Only a third of people urgently referred to Northern Lincolnshire and Goole Trust with suspected bowel cancer receive a diagnosis or an all-clear within four weeks, figures reveal.
Cancer support charities say urgent investment is required to tackle workforce shortages and reduce waiting times across England which they say can tragically slim patients' chances of survival.
The figures come just months away from the introduction of a new NHS target for three-quarters of all suspected cancer patients to get their diagnosis within four weeks.
NHS England figures show in June, just 94 out of 279 patients (34%) with suspected cancer at Northern Lincolnshire and Goole NHS Foundation Trust had received their test results within 28 days of an urgent GP referral.
Of the patients who were forced to wait longer, 49 had to wait at least 62 days.
Proportionately, suspected bowel cancer patients were more likely to wait over four weeks than those being tested for breast, lung or skin cancers following an urgent referral to the trust.
The figures exclude those referred through screening programmes, where it is not mandatory to log the cancer type.
From October, NHS trusts will be required to provide a result to 75% of all suspected cancer patients within four weeks as part of the new faster diagnosis standard.
It is aimed at getting treatment started sooner to those who need it, and placing minds at rest more quickly for those who are all-clear.
But charity Bowel Cancer UK said staffing shortages meant more funding was needed to carry out enough endoscopies, which can diagnose bowel cancer.
Chief executive Genevieve Edwards said: "Bowel cancer is the UK's second biggest cancer killer, but it's treatable and curable, especially if diagnosed early, and it's tragic that some patients will face poorer outcomes as a result of having to wait too long for tests and treatment."
Cancer Research UK also called for long-term investment into the workforce as well as for diagnostic equipment.
The charity's head of policy, Kruti Shortri, said: "Endoscopy is vital for the diagnosis of a number of cancers, in particular gastrointestinal cancers.
"As with all diagnostic services it was hit hard by the pandemic, but even before this the service was under considerable strain as staff numbers and equipment simply weren’t rising to match demand."
Separate NHS England figures also show how many people were waiting for an endoscopy in June.
At Northern Lincolnshire and Goole Trust, 562 people were on the waiting list – including 47 who had been waiting six weeks or more and 20 on the list for at least 13 weeks.
Across England, 88,000 people were waiting for an endoscopy in June.
NHS England said it was continuing to make progress through the pandemic with a quarter of a million people tested for cancer in June – the second-highest monthly number on record and 42% more than in the same month last year.
National medical director for England, Professor Stephen Powis, said: "NHS staff have made effective use of the additional resources made available to use to recover services which were inevitably disrupted during the pandemic, and we are continuing to tackle the Covid backlog."