Almost 10,000 women did not take up a potentially life-saving test for breast cancer.
Figures from the Health and Social Care Information Centre showed 23 per cent of women in Kirklees, aged 53 to 70 and eligible for breast screenings, failed to respond to their invitations between 2012/2013.
Kirklees Council health chiefs claimed early diagnosis from breast screenings could be crucial to improving survival rates.
A council spokesman said: “The aim of breast screening is to find breast cancer at an early stage when any changes in the breast are often too small to feel.
“Women are urged to take up their appointment when they receive a letter offering it.
“If they have any concerns about breast health or have missed a screening appointment they should contact their GP.”
The latest figures also revealed the national uptake of routine scanning invitations has fallen for the second year running.
Coun Molly Walton, Kirklees Cabinet member for Health, Well Being and Communities, said: “The number of women not taking the tests is a concern and we should not ignore them. They are there to help women in the district.”
HSCIC chief executive Alan Perkins said: “It goes without saying that the impact of breast cancer on people and their families can be severe and life-changing.
“This is why data included in the report is so enormously important.
“The figures point to a fall in the proportion of women who are taking up their screening invitation for the second year running – and while this is a relatively small fall in percentage terms, it is nevertheless a vital piece of information for health professionals and the public.”
Under the NHS screening programme, women are invited for three-yearly mammograms or breast X-rays between the ages of 50 and 70 years.
The age limits are being extended to 47-73.
Screenings check the breasts for signs of cancer and can spot cancers that are too small to see or feel.