Cancer survival could fall as a result of the Covid-19 pandemic, experts have warned.

Cancer Research UK said it is “really worried” about the impact of the crisis.

It said it is “essential” that cancer services continue to be restored and recover over winter, “otherwise we’re in danger of replacing one health crisis with another in time”.

The warning came as the charity estimated that three million people in the UK have missed out on cancer screening since the end of March.

And more than 350,000 people who would normally be urgently referred to hospital with suspected cancer symptoms were not.

People have been urged to come forward with any worrying symptoms, with experts reiterating the message that the health service is open for business in the safest way possible.

CRUK said the number of urgent suspected lung cancer referrals has been the slowest among cancer types to recover since April.

Since March, more than 16,000 fewer patients were urgently referred for lung cancer tests, it said.

Michelle Mitchell, chief executive of Cancer Research UK, said: “Without a doubt, Covid-19 has had a really devastating impact on cancer services and patients.

“Cancer survival here in the UK lags behind comparable countries – Ireland, Norway, Canada, Australia – but the pandemic has made this worse, leaving millions of patients in a backlog waiting for cancer screening, urgent referrals and treatment, and we at Cancer Research UK really fear that this will mean poor survival for cancer patients.”

CRUK said the biggest monthly fall in urgent referrals was in April – during the peak of the first wave of the pandemic.

While the numbers are steadily improving, they are still lower than before lockdown, it added.

Across the UK, around 31,000 fewer patients started treatment between April and July – a 26% reduction compared with the same timeframe in 2019.

A combination of factors could be at play, including a reluctance from patients to seek help, leading to a reduction in referrals, and the pausing of screening programmes and some diagnostic tests.

Ms Mitchell said NHS staff have worked “tirelessly” but are now facing a resurgence of Covid-19 on top of usual winter pressures.

But she added: “It’s essential that we keep cancer treatments and cancer services up and running.”

The charity said there needs to be a plan in place involving encouraging people to come forward with signs and symptoms driving an urgent referral, ensuring that screening continues, and ensuring that the surgical hubs continue to run with protected Covid spaces.

Ms Mitchell said: “It’s absolutely essential that cancer services continue to restore and recover during the winter period, because otherwise we’re in danger of replacing one health crisis with another in time.”

Meanwhile, it said that the Government Spending Review is a good opportunity to make sure the NHS has the staff and equipment it needs to diagnose and treat more cancers earlier.

Ms Mitchell added: “We’re at a critical juncture, where clearly we’re worried about the impact Covid will have on the country, on the economy, on our families, but we should also be really worried about the impact on cancer survival.”

Professor Charles Swanton, Cancer Research UK’s chief clinician and group leader at The Francis Crick Institute, said: “The legacy of the first wave of the Covid pandemic has created enormous problems for patients suffering from cancer.

“Cancer Research UK estimates that there are about three million patients waiting to be screened – essentially the backlog from lockdown and the first wave (of the) pandemic.”

Dr Neil Smith, Cancer Research UK’s GP for Lancashire and South Cumbria Cancer Alliance, said the second wave of Covid-19 is already being felt in GP practices – in his surgery a third of staff are off because of coronavirus.

“I am worried about this winter. I’ve been doing this job for 25 years, I think it’s going to be the hardest time that we’re all going to see,” he said.

“My biggest fear is that in future years I’ll be doing more home visits for palliative care because I, as a GP, am not diagnosing my patients soon enough this year as I’d like to, as I have done in the past.

“The biggest thing that I have noticed during coronavirus is that fewer of my patients are actually coming forwards to tell me about the signs and symptoms of cancer. They seem to be reluctant to do so.

“It is very understandable. If somebody has a cough they are a pariah, they have got to stay at home and do a Covid test and isolate for two weeks.”

He added: “In the future, even more of my patients are going to be diagnosed even later with lung cancer.

“And the other area I’m particularly worried about – I’m seeing far fewer men with urinary symptoms and I do think I’ll be diagnosing prostate cancer later because of Covid.

“As a GP, I’d like to tell patients if they have got any symptoms or signs that they are worried about, contact your GP.

“Cancer doesn’t stop for a pandemic.”

A spokeswoman for the NHS in England said: “Cancer treatments are now back to usual levels and routine screening services have now safely resumed across the country.

“A recent study by ONS (Office for National Statistics) and others estimated that the brief pause in screening would in fact have a very modest impact on health.”