NHS England figures show at Barnsley Hospital, 3,169 patients were waiting for one of ten standard tests, such as an MRI scan, non-obstetric ultrasound or gastroscopy at the end of last month.
Of them, 238 - eight per cent - had been waiting for at least six weeks.
A health charity says poor NHS performance demonstrates the need for a workforce plan and greater funding across the health service.
Saoirse Mallorie, senior analyst at think-tank King’s Fund, a health charity, said: “This is yet another month of worrying statistics that show people not getting the standard of care they need, and yet another month waiting for the oft-promised and long-overdue workforce plan, which must have funding to underpin it.
“There also needs to be a shift in focus from receiving care in hospitals to care closer to home.
“This involves investing properly in primary and community care services, as well as social care reform and full engagement with the voluntary sector.”
Separate figures from NHS England show of the 53 patients urgently referred by the NHS who were treated at Barnsley Hospital in March, 41 were receiving cancer treatment within two months of their referral.
A month previously - when 51 patients were referred - 35 were treated within 62 days.
In March 2022, 34 patients were treated within this period, out of 47 that were referred.
Some 260,308 urgent cancer referrals were made by GPs in England in March - but the proportion of cancer patients who saw a specialist within two weeks of being referred urgently by their GP fell from 86.1 per cent in February to 83.9 per cent in March, remaining below the 93 per cent target.
Professor Pat Price, co-founder of the #CatchUpWithCancer campaign, added: “These quarterly NHS cancer figures are the worst on record.
“They show despite the heroic efforts of the frontline staff, cancer patients are likely to continue to die from waiting as well as from cancer itself.
“Without extra treatment capacity and a dedicated cancer plan we will continue to condemn cancer patients to avoidable delays and lives will be lost unnecessarily.”
Other figures show 20,878 patients were waiting for non-urgent elective operations or treatment at Barnsley Hospital at the end of March - up from 20,122 in February, and 15,863 in March last year.
The median waiting time from referral at an NHS trust to treatment at Barnsley Hospital was nine weeks at the end of March - down from ten weeks in February.
A Department of Health and Social Care spokesperson said: “The NHS has seen and treated record numbers of cancer patients over the last two years and in March nearly 92 per cent of patients started cancer treatment within one month.
“Cancer is being diagnosed at an earlier stage more often, with survival rates improving across almost all types of cancer and NHS England continues to actively support those trusts requiring the greatest help to cut hospital waiting lists, which is a top priority for government.”