Sarah Boyle says her baby son helped 'detect' her breast cancer.

A British mum says she has her infant son to thank for her life, after he helped to detect her breast cancer.

Sarah Boyle told The Telegraph five-month-old Teddy suddenly began refusing milk from her right breast and would scream and wail if she attempted to feed him.

“He just wasn’t having it,” she told the UK newspaper.

“I had no problems with my left breast, but every time I tried with my right he would start screaming and get very upset. He wouldn’t go near it.”

The 26-year-old had noticed a lump in her breast that was diagnosed as a benign cyst in 2013. In the ensuing years she received regular checks and was each time told it was fine.

Teddy's refusal to go near his mother's right breast for about a month convinced her to go back to her GP, who initially insisted she was fine.

However, when her son's feeding hadn't improved in two months, Sarah went back - this time insisting on a scan.

"I felt as if Teddy was trying to tell me something. It was, what you might call, a mother's instinct," she said, suggesting that the boy may not have liked the taste of her milk from that breast.

An ultrasound and follow-up biopsy in November 2016 showed that within the lump in was, in fact, a non-hormonal type of breast cancer that is extremely rare in young women.

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The Staffordshire woman is now undergoing chemotherapy and planning to have a double mastectomy with reconstruction.

"Teddy is my hero – if it hadn’t been for him I would never have suspected I had cancer," the call centre worker told Metro.

"My consultant told me that breastfeeding helps a mother and baby bond. In my case it did more than that – it saved my life."

While doctors were reluctant to give credit to the now one-year-old for the detection, the biopsy confirmed the cancer inside the cyst had been growing for three months - the exact same time Sarah claimed her son stopped feeding.

"Nobody can say for certain whether it was Teddy, but I know that if it wasn't for him then this time next year it could've been completely different if I'd listened to doctors, but instead I listened to Teddy," she told the BBC.

"[It's] because of him that I'm now being treated."

Health professional Catherine Priestley was quick to point out that a baby refusing to breastfeed didn't necessarily mean a mum might have cancer, and it was always a good idea to check any changes.

"While there are many reasons why a baby may stop feeding, getting any new breast changes checked out must be top of the list," she told the BBC.