Two thirds of Australian women do not know that a woman's risk of developing breast cancer increases as she gets older, a National Breast Cancer Centre survey has found.

Even fewer women (28 per cent) thought a family history of breast cancer on their father's side was important in determining their risk of developing the disease.

Nearly one quarter of women wrongly thought being overweight posed no risk for developing breast cancer.

Many (42 per cent) mistakenly rated stress as a big risk factor for developing breast cancer.

And one in three Australian women who noticed a change in the look or feel of their breast waited more than one month before seeking medical advice, the survey showed.

Over 3000 women aged 30 to 69 were questioned.

"These Survey results tell us it's time to cut through the myths about breast cancer and highlight the importance of finding the disease early." said Dr Zorbas, Director of the National Breast Cancer Centre.

"These findings are very disturbing, particularly as we know the earlier the cancer is detected the better the chance of survival. What we thought Australian women knew about breast cancer is clearly not the case, and it is potentially putting lives at risk."

Breast cancer is the most common cause of cancer-related death in women in Australia.

Every year around 12,000 women are diagnosed with breast cancer and 2,600 die from the disease.