The Manchester Trust not a met a new key Government cancer waiting time target in any of the six months following its introduction, figures reveal.
Cancer Research UK said the Government needs to invest more in the NHS and raise its target to prevent tens of thousands of people across England being "left in limbo" every month.
The Government introduced a new Faster Diagnostic Standard target last year for 75% of people on certain cancer-related referrals to receive either a diagnosis or the all-clear within 28 days.
But monthly NHS England figures show that between October and March, Manchester University NHS Foundation Trust did not meet this target once.
In March – the most recent data available – the Trust got back to 55.2% of its 4,625 patients within 28 days – down from 57% in February.
This means 2,071 patients at the Manchester Trust were waiting too long to find out whether or not they have cancer in the most recent month.
Cancer Research UK says they are among an average of 65,4000 people across England affected every month.
The 75% target has not been reached yet nationally – and fell to just 73.1% in the most recent month.
Michelle Mitchell, Cancer Research UK’s chief executive, said: “Cancer waiting targets have been missed for years – the pandemic has only made this worse.
"Where you live affects how long you will have to wait – this is bringing stress and anxiety for those waiting."
She urged people to see their GP if they notice any unusual changes to their health as cancer diagnosed at an early stage is more likely to be treated successfully, but called on the Government to do more.
Cancer Research UK says the new standard aims to produce swifter diagnoses for patients, but due to chronic shortages of specialists, the target is too low.
The charity is calling on the Government to raise the goal to 95% within its upcoming 10-year cancer plan to reduce the number of people "left in limbo" each month, as well as plan to ensure the NHS can deliver it.
The proportion of patients who received a diagnosis or had cancer ruled out within 28 days of an urgent suspected cancer referral nationally was at its lowest level in January – just 63.8%.
At the Manchester Trust, the worst performing month was also January, when just 35.4% of 4,134 patients heard back.
Professor Charles Swanton, Cancer Research UK’s chief clinician, said a robust plan and sustained investment could help diagnose people quicker and earlier, and save more lives.
A Department of Health and Social Care spokesman said: “We are improving outcomes for cancer patients across England and our new 10-Year Cancer Plan will set out how we will lead Europe in cancer care."
He added that the Government's record investment in the NHS aims to cut waiting times, including delivering an extra nine million checks, scans and operations by 2025 as part of plans to tackle the Covid backlog.