At least one in five women have not checked for signs of breast cancer in the last year, a YouGov poll suggests.
The survey of 1,004 women and 729 men found that 76% of women aged 18 and over had ever checked for signs of breast cancer, including 41% who had done so in the last month.
Some 18% said they had checked themselves in the last six months but 11% of women overall had never checked their breasts.
Among the men, 80% were aware they could develop breast cancer themselves, though only one in five has ever done a breast exam.
Overall, most men (69%) have never performed a check for signs of breast cancer.
The new poll, shared with the PA news agency, also found that nearly two-thirds of Britons (63%) have been affected by breast cancer either directly or through a loved one.
A quarter (27%) of people have a family member who has had breast cancer, 22% have had a friend diagnosed and 2% have had it themselves.
A further 33% knew somebody else with breast cancer.
Meanwhile, women were more likely to know or have known someone with the illness (72%), compared to men (53%).