Black women in England are almost twice as likely to be diagnosed with advanced breast cancer as white women, according to a new analysis by Cancer Research UK and Public Health England.
Late-stage disease is found in about 25% of black African and 22% of black Caribbean breast cancer patients.
In white breast cancer patients, the figure is 13%.
Experts say there are many reasons for this. Vital ones to change are low awareness of symptoms and screening.
According to Cancer Research UK, black women are less likely than white women to go for a mammogram when invited by the NHS.
Spotting cancer early is important because the sooner it can be treated, the better the outcome.
A support group in Leeds helps women of black African and Caribbean descent who have either had breast cancer themselves or have loved ones who have.
One woman there told the BBC: "A lot of us black people bury our head in the sand. 'Oh, me, well, I don't need to go, there's nothing wrong with me.'"
Another said: "I find a lot of people, they'll find out something is wrong but they keep it to themselves and they're praying. They're praying that God will heal them."
Heather Nelson, who works for BME Cancer Voice, said: "Women, especially women of colour, are less likely to go for screening.
"You'll get leaflets through your door and they will be predominantly of white, middle-class women. There's no representation of South Asian, African descent et cetera.
"If you get information like that, you're going to look and think, 'That's not about me.'"
Most breast cancers are still diagnosed at an early stage, across all ethnic groups, the data for 2012-13 shows.
Dr Julie Sharp, of Cancer Research UK, said: "If you notice something that isn't normal for you, or you've a symptom that's not gone away or has got worse, getting it checked out promptly could save your life."
Lumps are not the only sign of possible breast cancer.
Women should also get checked if they notice any changes to their breasts such as nipple discharge or changes to the skin.
Breast screening (mammogram) is offered to all women in England aged 50-70.
The NHS is in the process of extending the programme as a trial, offering screening to some women aged 47-73.
Women over the age of 70 will stop receiving screening invitations but can arrange an appointment by contacting their local screening unit.
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