London has the lowest uptake of breast cancer screening in the country, 13% below the national average, statistics show.
A report from the London Assembly reveals that more than a third of women in the capital who are invited for breast cancer screening fail to take up the offer.
Large disparities in the uptake of screening have been revealed across London boroughs.
Older women in more affluent areas are also most at risk of developing breast cancer, although survival rates are lower in more deprived areas.
Joanne McCartney, chair of the Assembly's Health and Public Services Committee, said: "Breast screening saves 1,400 lives every year, yet more lives could be saved if more women were screened.
"Early diagnosis is crucial to survival, which is why our report puts forward a number of ways to improve the screening rates in the capital and to make women more aware of the symptoms and risks of breast cancer."
The report recommends a london-wide call and recall service that offers appointments to women outside working hours at a location of their choice should be set up as part of healthcare for London.
Maggie Alexander, director of policy and campaigns at Breakthrough Breast Cancer, said: "GPs can play a vital role in promoting screening to all women over 50 and this, together with the recommendation to establish a London-wide service to improve access and flexibility of appointments, could make a real difference to whether or not women attend."