Watch a report from ITV Anglia's Graham Stothard
Patients and charities have spoken of their worries at the impact of people not using the NHS to get cancer diagnoses.
A new report by Macmillan Cancer Support estimates that around 50,000 people across the UK have an undiagnosed cancer.
Screenings were put on hold during the initial lockdown, and warnings that the NHS could be overwhelmed with Covid-19 cases this winter led to the announcement of a second lockdown in England.
Now the charity are concerned that patients are not going into doctors' surgeries or hospitals to receive check-ups and treatment, out of fear they might catch coronavirus.
Helen Liles, from Macmillan Cancer Support's team in the East of England, said: "Our main message really is that if you have any concerns about your health, any lumps and bumps, anything unusual please do go to your doctor, your GP.
"The NHS is open for business, your GP will see you, it may not be face to face, but your GP will see you and will refer you."
Her comments have been echoed by Dr Daksha Trivedi, a public health lecturer at the University of Hertfordshire, who is recovering from cancer herself and regularly visits hospital for check-ups.
She said: "I actually spoke to my oncology nurse and she reassured me and said, when you come to the hospital there'll be separate corridors and there will be separate things and everybody will be having their face coverings and they instructed me that as long as I had my face covering and I kept my distance, that everything was safe."
Dr Trivedi has set up a support group for people with cancer in Bedfordshire, such as Eddie Thompson, who has oesophageal cancer.
He continued using hospitals for treatment during the first lockdown.
He said: "It's all a bit strange because you can't see people's faces who are treating you. It's strange, but it's probably responsible for me being here now and I urge everybody to go for it."
Keeping coming in for appointments, Addenbrooke's tell patients
ITV Anglia's Jonathan Wills spoke to Dr Sue Broster, Deputy Medical Director at Addenbrooke's
Addenbrooke's Hospital in Cambridge has urged patients invited in for treatment to keep their appointments.
Dr Sue Broster, Deputy Medical Director, said: "One of our significant concerns is that patients are scared about coming into hospital, they’re worried, they see images in the press that make them very concerned about Covid patients in the hospital and catching Covid in the hospital. I’d like to take this opportunity to reassure patients that we are doing everything possible to keep them safe.
"If they don’t come in there’s a potential really significant long term impact on their own health, not just today but in the weeks and months ahead."