But every year, nearly a fifth of women (17%) who are diagnosed with breast cancer put off seeing their GP for more than a month after first spotting a symptom, a survey has suggested.
Breast Cancer Care warned that there is still confusion around the signs of breast cancer and more needs to be done to encourage women to go to their GP sooner.
In a survey of breast cancer patients released on Monday, the charity found a third of the women who waited more than a month before seeing their GP did so because they did not think the symptom was serious enough.
A total of 5% of women waited as long as six months before making an appointment, potentially putting their lives at risk.
Samia al Qadhi, chief executive at Breast Cancer Care, said: "There have been many awareness raising campaigns around breast cancer symptoms, but our survey suggests that the job still isn't done.
"The sooner a cancer is diagnosed, the more effective treatment is likely to be so it is extremely concerning that some women are waiting more than six months to visit their GP after finding a breast symptom.
"Our survey identifies the main reasons for a delay could be the fear of being diagnosed and not realising a symptom may be breast cancer.
"We know how scary it can be to find a breast change but we want to reassure women that an early diagnosis of breast cancer can mean simpler and more effective treatment.
"We are urging women of any age to get to know their body by looking at and feeling their breasts regularly - there's no right or wrong way - and if they find any unusual changes for them to not put off visiting their GP."
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A total of 10% of the 403 women surveyed did not have the common symptom of a lump and instead had puckering or dimpling of the skin or redness or rash on the breast.
In some cases these other symptoms can indicate a fast-growing type of breast cancer.
Mother-of-one Fiona Lewis, 44, from Taunton, who was diagnosed with breast cancer in 2012, warned other women to "trust their instincts".
"It was very odd, it was like my breast had a strange grainy texture and had hardened," she said.
"It felt weird for a couple of months, but I just wasn't sure what it meant. I spoke to my partner Andy about it and he said that if it felt different, I had to go and get it checked out. It was such a shock when I was diagnosed."