A charity has expressed “enormous concern” over a significant dip in the number of children and young people diagnosed with cancer during the first wave of the pandemic.

A new study found a “substantial reduction in childhood, teenage and young adult cancer detection” in England during the first few months of the crisis.

Researchers from the University of Oxford set out to investigate how the pandemic had affected children with cancer.

They examined incidence rates, time to diagnosis and cancer-related intensive care admissions for children and young people up to the age of 25 during the first wave of the pandemic.

They obtained data from February 1 2020 to August 15 and compared this to the same time frame in the three years before Covid struck.

A total of 380 cancers were diagnosed in children and young people during this six-and-a-half month period in 2020.

More than 2,600 cases were diagnosed during the same time frame in the preceding three years.

The study, which is being presented as an abstract to the NCRI Festival, concluded there was a 17% reduction in the number of cases of cancer diagnosed last year compared to the previous three years.

The finding was especially true for tumours of the central nervous system – where there was a 38% reduction in new cases – and lymphomas, where there was a 28% fall.

Children diagnosed during the pandemic were significantly more likely to need intensive care (ICU) support prior to their diagnosis – suggesting they were sicker by the time they were diagnosed.

The authors found that the average time between diagnosis and the start of treatment was slightly shorter during the first wave compared to the period before the pandemic.

The authors concluded: “The Covid-19 pandemic has led to substantial reduction in childhood, teenage and young adult cancer detection during the first wave, with an increase in cancer-related ICU admissions, suggesting more severe baseline disease at diagnosis.”

One of the authors, Dr Defne Saatci, said: “Spotting cancer early and starting treatment promptly gives children and young people the best chance of surviving.

“We already know that the Covid-19 pandemic led to worrying delays in diagnosis and treatment for many adults with cancer, so we wanted to understand how the pandemic affected children’s cancer services.”

Lead researcher Professor Julia Hippisley-Cox said: “We found that more children were admitted to intensive care prior to their cancer diagnosis during the pandemic.

Even before the pandemic, we knew that young people’s route to diagnosis could be long and complicated. Early diagnosis can save lives

“A possible explanation is that these children waited longer to see a doctor and, therefore, may have been more unwell at the time of their diagnosis.

“Together with the lower numbers of cancer diagnoses in the first wave, this study suggests Covid-19 may have had a serious impact on early diagnosis in this group of patients.

“As we recover from the pandemic, it’s vital that we get diagnosis of cancer in children and young people back on track as quickly as possible.”

Kate Collins, chief executive of the Teenage Cancer Trust, said: “Until now there was limited evidence about the impact of the pandemic on the cancer diagnosis of children and young people.

“Too often young people with cancer are forgotten or overlooked, especially in data collection, making them invisible in the system.

“Even before the pandemic, we knew that young people’s route to diagnosis could be long and complicated. Early diagnosis can save lives.

“The fact the pandemic has delayed diagnosis is an enormous concern and it is essential to understand not only the reasons the pandemic affected diagnosis but the impact this is having on children and young people with cancer, and what they need now from the healthcare services who care for them.”

It comes as the NHS faces the biggest ever backlog of care in its history.

Millions of people are waiting for hospital treatment in England alone.

Meanwhile, a damning report published in September concluded that it could take more than a decade to clear the cancer backlog in England.

Research from the Institute for Public Policy Research think tank and the CF health consultancy showed that during the height of the pandemic 369,000 fewer people than expected were referred to a specialist with suspected cancer.

Cancer Research UK warned that cancer survival rates “could go backwards” due to the backlog of care.

An NHS spokesperson said: “This partial data does not reflect the full extent to which NHS staff maintained cancer services for children during the pandemic, with overall referral and treatment numbers, including for children, back to usual levels.

“The NHS remains open and ready to care for you so it’s vitally important that people experiencing cancer symptoms come forward and get checked.”