Addenbrooke's hospital in Cambridge is the first in England to restart bowel cancer screening.
Like many services at the hospital, colonoscopies were put on hold in March so staff could focus on patients with Covid-19 or those requiring more urgent care.
The hospital's bowel cancer screening programme is offered to those over 60.
"Patients who test positive have an approximately one in 10 chance of having bowel cancer', Edel McDermott, clinical lead for bowel cancer screening, said.
"The earlier we identify and treat those patients the better the outcome. If we pick it up early, we can cure them and they can have a normal life expectancy and potentially a normal quality of life.
"Whereas if a patient is not picked up early, then we may not be able to treat them at all. Bowel cancer screening dramatically affects patient outcomes."
A colonoscopy, a test to check inside your bowels, is usually carried out two weeks after receiving a positive test, but some patients were forced to wait three months.
Staff at Addenbrooke's have been carrying out telephone appointments during lockdown, prioritising those most at risk. The hospital has now cleared its backlog of colonoscopies and will start seeing patients who require further investigations following the reopening of the unit.