More than 125,500 people were waiting to be seen for eight key diagnostic tests as of September 30 – an increase of over 10,000 since three months’ earlier.
This figure is 22 per cent higher than it was on the same date in 2020, and 42 per cent higher than it was in the year before the Covid-19 pandemic began.
The tests, many of which are used to diagnose cancer, include endoscopy, colonoscopy, CT and MRI scans.
“The number of people waiting too long for a test to determine whether they have cancer is deeply worrying,” said David Ferguson, public affairs manager for Cancer Research UK in Scotland.
“Without action, it could take years to clear the backlog caused by the pandemic. And we’re very concerned that, for some patients, delays to diagnosis and starting treatment could make it more difficult to treat their cancer.
"This is a completely unacceptable situation.
“Substantial staff shortages, which existed before the pandemic, are at the heart of these delays. NHS winter pressures will only make the situation worse. This must be addressed urgently.”
Scottish Labour said the new figures showed the NHS was facing a “deepening crisis”, while Scottish Conservative MSP Dr Sandesh Gulhane labelled them “hugely concerning and unacceptable”.
“These delays create greater stress for patients, on top of their underlying health problems, and my heart goes out to them,” he said.
Liberal Democrat leader Alex Cole-Hamilton said: “We know that early diagnosis and treatment is crucial to a patient's chances of survival, so this raises enormous red flags. Chances of survival should not depend on a postcode.”
Some 42 per cent of those waiting have been doing so for more than six weeks, the Scottish Government target, compared to 19 per cent in the year to March 2020.
Waiting times vary between health boards, with just 3 per cent waiting more than six weeks for endoscopy tests at NHS Dumfries and Galloway compared to 72 per cent at NHS Lothian.
For radiology tests, 10 per cent waited more than six weeks at NHS Forth Valley, while 53 per cent did so in NHS Lanarkshire.
Mr Ferguson urged the Scottish Government to take action.
“We need a detailed plan from the Scottish Government to ensure we have enough staff to test and diagnose cancer,” he said.
"Funding to deliver the right equipment and improved ways of working is also crucial. The Scottish Budget must deliver the investment needed to meet these challenges.”
The Scottish Government has announced a £70 million Endoscopy and Urology Diagnostic Recovery and Renewal plan, aimed at balancing capacity with demand, as well as improving infrastructure and innovation.
A spokesperson said: “Patients continue to be seen based on their clinical urgency, for example, those referred with an urgent suspicion of cancer continue to be prioritised for key diagnostic tests.”
They added: “It is regrettable that we cannot mobilise to the degree and speed we all wish for, but we have to balance competing demands and pressures, making the best decisions we can, none of which are easy nor taken lightly.”