A baby who was born with a large tumour on his leg has been spared chemotherapy after whole genome sequencing revealed the lump was harmless.

Sara and Michael Bell, from St Neots, received concerning news about their baby, Oliver just a few days before his birth.

An ultrasound showed a large tumour on his right leg measuring approximately 6cm in length.

After his birth, blood tests were taken and within two days the family were referred to the paediatric oncology team at Cambridge University Hospitals NHS Foundation Trust (CUH).

“It was really scary,” said Sara.

“At Addenbrooke’s Hospital, more blood tests were taken and we were preparing for the worst, but then a consultant offered us whole genome sequencing.”

Whole genome sequencing is the process of determining the entirety, or nearly the entirety, of the DNA sequence of a person’s genome at a single time.

It captures both large and small variants that can be missed with other targeted approaches.

In Oliver’s case, the whole genome of the tumour was sequenced and compared to the sequenced DNA in his blood cells.

Oliver’s consultant was Dr Sam Behjati, a paediatric oncologist at CHU and group leader at the Wellcome Sanger Institute.

Dr Behjati explained to Sara and Michael that results from the test, which just needed another sample of Oliver’s blood, would give them the most amount of detail possible on what they were dealing with.

He said: “Under the microscope, Oliver’s tumour initially looked like a type of sarcoma called infantile fibrosarcoma which we typically treat with surgery, chemotherapy or other specific drugs.

“Although initially Oliver’s seemed to be infantile fibrosarcoma, standard molecular tests did not confirm this diagnosis.”

Whole genome sequencing solved the mystery.

It highlighted that Oliver’s tumour had a particular mutation which completely changed the diagnosis of Oliver’s tumour from cancer into a benign tumour type called myofibroma.

“This revised diagnosis could only have been achieved with whole genome sequencing,” said Dr Behjati.

“It meant we were able to chance our treatment plan, opting to simply observe the tumour in the first instance, which has since started to shrink without any treatment.”

Sara said that the team at Addenbrooke's were “incredible”.

“They were honest with us at every step, keeping us well informed of what we were dealing with,” she said.

“For the first eight weeks of Oliver being born, we lived with the prospect of cancer dominating our lives and chemotherapy being the next step.

“Two weeks after his whole genome test, everything changed and we couldn’t be more relieved.

“Oliver is now getting bigger and stronger every day. It’s fantastic.”

The test Oliver had is available on the National Genomic Trust Directory and is offered routinely for all children with cancer at CUH.

Patients have been referred to CUH from hospitals across the East of England for this “highly specialised” treatment.

Scientists at East Genomic Laboratory Hub provide expert analysis and interpretation of the patients WGS reports to help inform the clinical team's decisions on the best course of treatment.

Oliver’s dad, Michael, said: “Our lives were turned upside down when we thought Oliver would need surgery and chemotherapy.

“Receiving such clarity on the type of tumour we were dealing with was so important.”

He added: “We know we are really lucky to have such an outcome.

“It was like a miracle, a miracle test that told us he didn’t have cancer and we could go back to our normal lives.”