Key cancer waiting times have slipped to the worst on record, according to the latest figures.
Opposition parties described the statistics as a “national scandal”, while cancer charities called for urgent action.
The Scottish Government has already announced extra funding to cut waiting times for diagnostic tests.
The figures show only 85 per cent of patients urgently referred with a suspicion of cancer started treatment within the 62-day standard between January and March, falling short of the 95 per cent target.
The figure was down from 87.1 per cent in the previous quarter and from 88.1 per cent in the same period the previous year.
Meanwhile 93.5 per cent of patients waited no more than 31 days from the decision to treat to the first cancer treatment, missing the 95 per cent target.
Performance slipped from 94.6 per cent in the previous three months and was down from 94.8 per cent in the same quarter in 2017.
Only NHS Borders, Lanarkshire and Shetland met the 62-day standard, while ten out of 15 boards met the 31-day standard.
Breast cancer was the only cancer type to meet the 62-day standard successfully, with 95.1 per cent.
Eight of the ten reported cancer types met the 31-day standard, with the standard missed in breast and urological cancers.
Gordon McLean of Macmillan Cancer Support said: “There’s an urgent need for health boards across Scotland to learn from the areas where targets are being met.”
Cancer Research UK said more action was needed in diagnostic services.
The Scottish Government this week announced an extra £6 million to help cut waiting times for endoscopies. It is hoped the number of people waiting for diagnostic tests will be cut by at least 2,500 by September and 5,000 by December.
It is part of a £14m action plan to ensure that those who have been waiting for more than six weeks are seen as a matter of urgency.
Gregor McNie of Cancer Research UK said: “We welcome the Scottish Government’s decision to invest £6m to ensure more patients who need an endoscopy are seen within the target time.
“However, this is just one piece of the puzzle. Similar action is needed across other diagnostic services.”
Scottish Labour’s health spokesman Anas Sarwar said: “Having thousands of people wait too long is a national scandal. Health secretary Shona Robison’s legacy at health is one of horrendous mismanagement.”
Scottish Liberal Democrat MSP Alex Cole-Hamilton said new funding was announced because ministers “knew terrible performance figures were set to be published 24 hours later”.