Comfort was nine when her older sister told her she was going to flatten her chest with a stone to prevent her breasts from developing too soon, telling her it was for her own good.

“She said it’s so that girls don’t get abused as children or as teenagers,” Comfort said.

“But that didn’t prevent nothing,” she added. Born in Nigeria, Comfort moved to the UK with her family three years later, in 1998.

Five years ago, fluid started coming out from her nipple.

“I was really scared – I thought it might be cancer. It was barely six months after I got married. I booked a mammogram – they didn’t find cancer, but they couldn’t explain why I was getting the milk.”

The practice to which Comfort was subjected originated in west Africa and is extremely secretive. There is no official data on how widespread it is.

The perpetrators, usually mothers, consider it a traditional custom that protects girls from unwanted male attention, sexual harassment and rape. Medical experts and victims regard it as child abuse that could lead to physical and psychological scars, infections, inability to breastfeed, deformities and breast cancer.

Earlier this year, the Guardian revealed anecdotal evidence of dozens of British cases of the practice, in which a girl’s chest is “ironed” with a hot stone to delay breast formation. The British government was forced to issue a statement vowing to confront the ritual, which it described as child abuse.

Victims and those familiar with the practice say more must be done to root out a tradition that can have serious medical consequences.

Nwakanma Onyedikachi Chioma, a Lagos-based doctor and public health advocate, says it can seriously impair breast tissue.

“When they are inflamed, the immediate effects are trauma to the breast skin – some of those children actually lose their nipples in the process. Some of them have scarred skin, some of them have secondary infections.

“The trauma to the breast can lead to breast cancers and breast lumps. Continuous trauma to the breast is directly related to breast cancer,” she said.

“Someone needs to talk about it.”

Jose Bekono, a nurse based in Cameroon, lost his 28-year-old cousin Cathy to breast cancer in December 2018. Although doctors did not look into the breast ironing Cathy had endured aged nine, Bekono is convinced there is a link.

“After she had been breast ironed by her grandmother, she developed a hard lump in her chest,” he said. The lump remained and began to hurt several years ago. Soon after, she was diagnosed with breast cancer.

“I’ve seen others like her … Some had abscesses, cysts – but we were able to treat those.”

A senior Cameroonian gynaecologist, who did not wish to be named, said she had dealt with a case last year in which a 12-year-old girl died as a result of being breast-ironed with a stone that had burned through the whole of her breast. The Guardian has seen photos of the girl which are too distressing to publish.

“I’ve also seen first- and second-degree burns,” she said. “Only this morning, a 29-year-old woman came to see me. She had been breast-ironed as a child and is today psychologically scarred as a result. She is unable to tolerate physical intimacy with her husband.”

Ann Marie Christian, a UK-based safeguarding practitioner, said she met a teacher from a school in south-west London whose pupil confessed to having been breast-ironed by her mother when they lived in a west African country.

“She described it as a formality, something they just did every day, a chore, like washing up,” Christian said. “Her mother, without her father’s knowledge, used to do it in the mornings. She would help her change and then get some iron bars, heat them up, then would get the child to lie on the floor in her bedroom and the mother would roll these things across her chest, like a rolling pin.”

“She (the girl) almost thought it was part of having breasts. She thought it was like a sort of support, because her mum was doing it. She never questioned it.”

“It’s only with the conversation with this teacher that she thought: ‘Wow, I realise now it could be harmful.’ So the child was justifying it, was very culturally proud as well, and didn’t want to badmouth her culture.”

But speaking out can be risky, generating the wrath of an entire community that still sees the practice as part of a tradition.

Leyla Hussein, a British-Somali anti-FGM campaigner and psychotherapist, said it is not right to put the onus on communities alone to tackle the practice.

“Often the community doesn’t even know it is wrong. They don’t even tell you [it is happening],” she said. “When people assume something is normal, they’re not going to come and talk to you about it. To them it’s normal – actually, it may be a celebration! They may invite you to the party when it’s happening.”

Hussein added that the government should train GPs, nurses and midwives to discuss the subject with their patients. “I had never thought FGM was wrong until a health professional asked me,” she said.

Comfort says the police and social services should be taking incidents of breast ironing more seriously. “They shouldn’t be letting people go – it needs to stop,” she said.

“This issue has been going on for a long time – before I was born, before my mum was born,” said Comfort, adding that her mother had also been breast-ironed in Nigeria.

“It was brought from Africa into this country. Now the crime is also being committed in this country – so now it becomes an issue here.”

“It’s very foreign – and I understand the police don’t know how to deal with it right now, but it’s out there, it needs to be recognised,” she said, advocating education on the issue for schoolchildren.

“I think that if it was happening to a white British person, it would be a completely different conversation.”