Women are having to wait up to two years for the results of a gene test to tell them if have a raised risk of breast cancer, say campaigners.
Two key genes are linked to breast cancer
The tests can determine whether women are carrying either the BRCA1 or BRCA2 gene - both of which are linked to a raised breast cancer risk.
Women who carry the genes sometimes opt for extreme measures, such as having both breasts removed, to avoid cancer.
However, the charity CancerBACUP uncovered long waits for test results.
A survey by the charity found that in two (11%) of the 19 regional genetics centres which responded to their survey, women are waiting up to nine months for their first appointment.
Almost a third (32%) had more than a six month wait.
And in five centres (26%), women were waiting between one and two years for their test results to come through.
The government said in 2003 that by 2006 diagnostic test results should be made available within eight weeks.
CancerBACUP said it had identified 23 regional genetics centres in the UK that carry out genetic testing.
These centres are serviced by 16 molecular genetics laboratories which test the gene samples.
The research found that only six out of 12 (50%) molecular genetics labs which responded were currently examining the whole of the key genes for signs of cancer-causing mutations.
Often labs focus only on a 60% portion of the relevant genes where the mutations are most likely to be found.
But in 2004 the National Institute for Health and Clinical Excellence (NICE) said the whole of the genes should be examined.
CancerBACUP said centres were required to carry out re-testing of samples to make sure that women who were previously tested for 60% of the BRCA genes were now tested for 100% of it.
But two of the labs said that it would take two years to clear this backlog.
Dr Andrea Pithers, CancerBACUP's genetic information project manager, said: "It is vital that genetic testing centres offer the same standard of service throughout the UK.
"We would like to see all women being informed that testing 100% of their BRCA genes is now available for everyone, in order to give them the choice over whether they would like to be retested.
"It's also important that centres speed up the time it takes to give women their test results.
"Although many of the centres say they will meet the government targets on this by 2006, our survey shows that some have a long way to go to achieve it."
A Department of Health spokesperson said the government had invested £11m in specialised genetics services since 2001, and a further £18m was announced in July 2004 to upgrade labs in England.
Labs were now equipped to undertake 100% screening, and had new equipment to deal with higher volumes of test more quickly.
"We are working with commissioners and providers of genetic services to ensure that patients are being appropriately referred in line with the NICE guideline, that backlogs of tests are cleared and that test results are delivered more quickly in the future."