An 18-year-old woman stands at the intersection of two featureless grey brick walls in Goma, in eastern Democratic Republic of the Congo. We can’t see her face, which is concealed by her left hand, but her right arm and neck are exposed and the burns on her skin are clearly visible. One night several years ago, the woman, whose name is Blandini and who lives on the streets of Goma with her two young children, was attacked by four men, who raped her in turn. Afterwards, they doused her with petrol and set her alight – “like a candle,” she recalls.

In the portrait of Blandini, taken by the Italian documentary photographer Alessandro Grassani, she sports a pair of cushioned red gloves. After the attack, in a bid to prevent anything like it from happening again, Blandini took up boxing. She joined an unregistered club, run by a former boxing champion of DRC who goes by the nickname Kibomango, and threw herself into training.

Nadine, 17, at the Friendship boxing club’s daily training session in an old football stadium. She says: ‘I live on the city streets and I have two children aged five and three. Since I started boxing, I feel more secure and if someone comes close to my children I’d know how to defend both them and myself. Many of my friends have been raped and I do not want to end up the same way.’ Photograph: Alessandro Grassani

“In a patriarchal society like Congo, it’s really difficult for women to box,” says Grassani. “It’s seen as a sport for men.” But Blandini is one of a growing group of women in Goma for whom boxing has become a lifeline, not just a form of self-defence in a country where sexual violence is rife, but also a source of companionship, purpose and hope for the future.

Grassani, who lives in Milan, learned about the Friendship boxing club prior to his trip to DRC last May. He had been commissioned to take photographs for a Goma-based NGO that runs hospitals in the region, but Grassani was on the lookout for other stories to explore during his visit. Getting in touch with Kibomango, who trained former child soldiers and homeless people for free, he asked if there were any women in his club. “He told me, ‘Yes, there are also women here.’”

It’s not surprising that women in Goma want to learn how to box. In 2010, Margot Wallström, the United Nations special representative on sexual violence in conflict, branded DRC “the rape capital of the world”, following a decade and a half of civil unrest during which sexual violence was routinely used as a weapon of war.

Ester, 18, says: ‘In my neighbourhood, I have seen friends of mine forced to have sexual intercourse or touched against their will. Whether I do boxing or not, sooner or later someone will end up wanting to hurt me. At least I will be ready to react.’ Photograph: Alessandro Grassani

Exact figures are impossible to come by, but the UN estimates that more than 200,000 Congolese women are rape survivors. The problem is particularly acute in the east of the country.

“Some of the women I met in Goma had suffered extreme violence,” says Grassani. “Living on the streets, they have to change where they sleep every night, so as not to be found by violent gangs that will rape them.” In this drastic situation, boxing provided a measure of security. “Now that they are training, they are fit, they can run faster, they are not afraid,” says Grassani. “For sure they will fight back.”

The Friendship boxing club meets every weekday morning from 6-8am at the Volcans football stadium in Goma, close to where its coach works as a mechanic. A former child soldier who lost an eye in a bomb blast, Kibomango (born Balezi Bagunda) has a formidable appearance – Grassani describes him as “the Rocky Balboa of Congo” – that belies his gentle manner.

Elysèe, 16, says: ‘I’ve been boxing for two years; it’s something that gives me strength and courage to defend myself. In this city, there is so much violence that you must always be ready to react. Thanks to boxing I feel ready to face these dangers.’ Photograph: Alessandro Grassani

“He’s very sweet with the kids and the women he’s training,” says Grassani. “He would tell them, ‘Everyone here is friends, it doesn’t matter if you were a child soldier, if you lived on the streets, if you’ve been raped… we’re all friends.’”

For the women training at Friendship, the main motivation was self-defence. At another club in the city that Grassani visited, the exclusively female Radi Star girls club, its members’ ambitions went beyond mere survival: they wanted to compete and win. “I don’t know much about boxing,” says Grassani, “but when you see someone run, fight and punch like they were doing – wow. They’re very strong, very aggressive.”

One woman who had been abandoned by her family told the photographer that she wanted to go to the US and become a champion like Muhammad Ali, then come back to DRC to open an orphanage for other abandoned children who needed help.

Blandini, 18, says: ‘I was kicked out of my family by my mother’s second husband and found myself on the streets. For a living, I do little jobs at people’s houses, although my biggest concerns are about defending myself. That’s why I do boxing. My husband left me when my second child was born, leaving me completely unprotected. Once I was covered with petrol by a group of men and set alight. The scars on my neck and my arm are the reminder of that night.’ Photograph: Alessandro Grassani

Grassani left Goma deeply impressed by the resilience of the female boxers and the generosity of their ambitions. His admiration was shared by the judges of the Sony world photography awards, who have shortlisted the Boxing Against Violence series in this year’s sport category. The winners will be announced on 17 April.

Grassani, who is currently working on a long-running project about environmental migration and border walls, says he’s delighted by the nomination and the extra attention it will bring to his subjects.

“The most important thing for me was not to portray these women as victims of something, but as the boss of their destiny,” Grassani says. “They are able to do everything. The courage and the strength of these women in the face of very serious violence was just incredible.”

The Sony world photography awards exhibition is at Somerset House, London WC2, 18 April-6 May