Could a blood test replace mammograms?

Baring your breasts in front of strangers and having your flesh uncomfortably pressed between two pieces of plastic – a procedure commonly known as a mammogram – is the standard test for breast cancer.

In future, all you may need to do is have a simple blood test.

A study funded by Cancer Research UK is examining whether a blood test can be used to detect breast cancer in its earliest stages.

It involves comparing DNA in the blood of women who are diagnosed with breast cancer with those who do not have the condition to see which DNA markers are consistent.

Scientists in Australia are hot on the test’s trail.

“The National Breast Cancer Foundation (NBCF) is funding a study involving experts from around the country to see whether blood tests can be used for the early detection of cancer,” says Dr Alison Butt, director of research investment at NBCF.

“We’re looking for fragments of DNA in the bloodstream from early tumours. It’s an exciting time. There have been incredible advances in cancer research recently.”

Early detection crucial

An Australian Institute of Health and Welfare (AIHW) report predicts the number of women diagnosed with breast cancer will rise from the current 37 cases a day to 47 cases a day in 2020 due to our ageing population. So those advances are needed – and they are already making a difference.

The AIHW report found breast cancer survival rates are up and early detection is part of that.

“This blood test could allow doctors to detect breast cancer very early on, before any physical signs appear, increasing a woman’s chance of survival,” Butt says.

Mammograms are unable to detect breast cancer until changes have occurred to the breast tissue. Some experts have also questioned the safety and efficacy of mammograms.

Mammogram problems

A recent study in the British Medical Journal suggested mammograms may actually increase the risk of breast cancer in young women with a mutated BRCA1 or BRCA2 gene due to the radiation exposure. False positives (where the test incorrectly shows breast cancer) and false negatives (where it fails to detect breast cancer) are also not uncommon.
“Mammograms aren’t 100 per cent accurate,” Butt says. “But they are the most valuable tool we have at present.”

Professor Helen Zorbas, CEO of Cancer Australia, agrees. “In Australia, population-based screening using mammography is the best early detection method available for reducing deaths from breast cancer.

“The BreastScreen Australia Program has reduced breast cancer mortality by up to 28 per cent in the target group [50 to 69 years] by enabling earlier diagnosis and more effective treatment.”

She says misdiagnosis is more common in younger women as their breast tissue is denser, making it more difficult to detect changes. After menopause the tissue becomes less dense.

“This is why mammograms become more effective as women get closer to 50,” Zorbas says.

New hope

Scientists hope the breast cancer blood test will be an effective screening tool for women of all ages and will also help doctors monitor how a cancer progresses.

“At present, when we detect breast cancer we don’t know what it is going to do,” Butt says. “Is it aggressive? Non-aggressive? We know of 10 different kinds of breast cancer, and one is very different to another. A blood test could guide treatment by pinpointing genetic abnormalities.”

There is hope the test could also be used to detect other cancers.

“It would be great if it worked for cancers that are hard to detect early on and that carry a high mortality rate, like ovarian cancer,” Butt says.

Another advantage of a blood test is the ease with which it can be carried out.

“At present, it is difficult for women in remote areas to be tested effectively,” Butt says. “It’s hard for the screening service to get to them, or for them to get to the screening service. A blood test could change that.”

Although the research is promising, it is in the early stages and the blood test won’t be available for five to 10 years.

“Thousands of blood samples need to be examined so we can say with certainty, yes, this is a breast cancer marker,” Butt says.

In the meantime, women are encouraged to check their breasts regularly.

“It is recommended that women of all ages, regardless of whether they have had mammographic screenings, are aware of how their breasts normally look and feel, and report any changes promptly to their GP,” Zorbas says.

Butt looks forward to a day when breast checks, blood tests and mammograms are all combined to provide doctors with as much information as possible.

“Information is the key for helping doctors recommend the correct treatment and helping women make informed decisions,” Butt says.

More blood-test breakthroughs

There are several other blood tests on the horizon or in use in limited capacities.

• Down syndrome: This test for unborn babies is 99.1 per cent accurate and much less invasive than existing tests, but is not yet available in Australia. Blood samples can be sent overseas for testing, but it’s costly.
• Autism: Trials to start in the US this year.
• Bowel cancer: Developed in Australia, the test is currently being trialled and could be available later this year.

 

Source: bodyandSoul