Elderly breast cancer warning
One in three breast cancers are in women over the age of 70, warns Public Health England (PHE).
The organisation is launching a campaign telling elderly women "don't assume you're past it" and to get any changes in their breasts checked out.
Around 13,500 women aged 70 and over are diagnosed with breast cancer in England each year.
However, survival rates in this age group are lower than in younger women, PHE said.
It is thought a lack of awareness of symptoms other than a lump, such as changes in breast size or shape, could be behind the poor survival rate.
Dr Yvonne Doyle, the regional director at Public Health England, said: "Research shows that women over 70 have low awareness of breast cancer symptoms, other than a lump.
"They're also more likely to delay presenting to their GP with breast cancer, which could ultimately affect their chance of survival.
"One in three women who get breast cancer are over 70, so don't assume you're past it or dismiss any symptoms as a sign of ageing."
The new "Be Clear on Cancer" campaign will include TV adverts.
The chief medical officer for England Dame Sally Davies said: "Awareness of symptoms and risk is low amongst this age group, meaning these women are more likely to be diagnosed at a late stage.
"The earlier breast cancer is diagnosed, the better the chance of survival."
Former Eastenders actress Barbara Windsor, 76, is supporting the campaign: "I met a lot of women affected by breast cancer when I was preparing for Peggy Mitchell's diagnosis in Eastenders, which made me realise just how important an early diagnosis is.
"You get to a certain age and think you're too old for some things, but breast cancer isn't one of them."