Tens of thousands of patients were waiting for routine treatment at Royal Cornwall Hospitals in July, figures show.
The shadow health secretary has branded the Prime Minister "inaction man" over rising waiting lists.
NHS England figures show 48,096 patients were waiting for non-urgent elective operations or treatment at Royal Cornwall Hospitals NHS Trust at the end of July – down slightly from 48,203 in June, but an increase on 43,479 in July 2022.
Of those, 2,825 (6%) had been waiting for longer than a year.
The median waiting time from referral at an NHS Trust to treatment at Royal Cornwall Hospitals was 13 weeks at the end of July – down from 14 weeks in June.
Nationally, 7.7 million people were waiting to start treatment at the end of July.
Shadow health secretary Wes Streeting said patients were waiting an "unacceptably long" time.
He added: "On the NHS, Rishi Sunak is Inaction Man, refusing to meet with doctors to end NHS strikes and adding to the Conservatives’ NHS backlog, leaving patients waiting for months on end in pain and agony."
Separate figures show 1.6 million patients in England were waiting for a key diagnostic test in July – the same as in June.
At Royal Cornwall Hospitals, 13,213 patients were waiting for one of 13 standard tests, such as an MRI scan, non-obstetric ultrasound or gastroscopy at this time.
Of them, 5,237 (40%) had been waiting for at least six weeks.
Other figures show cancer patients at Royal Cornwall Hospitals are not being seen quickly enough.
The NHS states 85% of cancer patients urgently referred by a GP should start treatment within 62 days.
But NHS England data shows just 70% of patients urgently referred by the NHS who received cancer treatment at Royal Cornwall Hospitals in July began treatment within two months of their referral.
That was down from both 73% in June, and 77% in July 2022.
Professor Pat Price, of the CatchUpWithCancer campaign, said the cancer figures show "we are still massively short in hitting the Government’s target of no more than 85% of cancer patients waiting more than 62 days between urgent GP referral and their first treatment."
"Today’s figures reveal that nearly 40% of cancer patients are missing their life-saving cancer treatment: this is over double the Government’s own target," she added.
The Prime Minister told the BBC on Thursday ongoing strikes by NHS staff were threatening his target of cutting waiting lists in 2023, acknowledging his promise could be missed.
Professor Julian Redhead, NHS England’s national clinical director for urgent and emergency care echoed Mr Sunak's comments on the impact of industrial action.
He said: “Today’s figures show that despite ongoing pressures across the NHS, including record demand for emergency care this summer, and an increase in Covid cases during July and August, NHS staff are continuing to deliver for patients."