Even so, there's the undeniable fact - it saves lives.
New research suggests as many as 2,000 women are saved every year in England as a result.
But, experts say it could be many, many more if all women aged 25-64 in the UK took the test when invited - which is normally every three years.
"Sometimes women feel a bit embarrassed or awkward about the whole thing," says Jess Kirby from Cancer Research UK.
