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New Blood Test Could Assist in Cancer Detection

Test May Lead to New Treatments for Aggressive Brain and Bone Cancer

Nov 25, 2009 Jo Jackson

The Children's Medical Research Institute in Australia has developed a blood test which will help both in the early diagnosis of aggressive cancers and their treatments.

A team of scientists at the Children's Medical Research Institute in Sydney have developed a new blood test which may assist in the early diagnosis of 15 per cent of all cancers. The cancers are aggressive brain and bone cancers and some breast and lung cancers where the cancer cells use the ALT mechanism to replicate and survive.

Patients diagnosed with the most aggressive brain cancers have an average survival rate of less than a year. The diagnosis alone can take months and often involves invasive surgery to take a sample of the tumour. The new test can be done with a normal blood test specimen and will provide more accurate life expectancy for patients.

Cancer Cells use Telomerase or the ALT Mechanism

When normal cells divide, the telomeres wear away a little. Telomeres are like protective DNA caps on the ends of chromosomes. Once the telomeres become too short, the cell dies naturally of old age. Cancer cells have two different mechanisms to prevent their telomeres shortening so that they can multiply indefinitely and live forever.

Most cancers (about 85 per cent) use an enzyme called telomerase to rebuild their telomeres. Telomerase was discovered by Australian-born scientist Elizabeth Blackburn in 1984, and in 2009 she won a Nobel Prize for her research on telomeres. The other 15 per cent of cancers, especially cancers like bone cancers, brain cancers, connective tissue cancers and to a lesser degree, breast cancer and lung cancer, use a method called alternative lengthening of telomeres, or ALT.

Early Detection of Cancer Using Blood Tests

Roger Reddel is director of the Children's Medical Research Institute and team member Jeremy Henson discovered that cancer cells that use the ALT mechanism produce tiny circles of DNA. The number of these DNA circles is closely related to the strength of the ALT mechanism. Cancers with the ALT mechanism drop these circles into the bloodstream so that the cancer can be quickly detected through a simple blood test to detect these circles.

The test only requires a normal blood sample and may also be able to show whether treatments such as chemotherapy are working by monitoring the amount of circles present. Researchers have been searching for a test to measure the activity of aggressive cancers for many years. The finding regarding the DNA circles has been published in international journal Nature Biotechnology.

New Test Could Lead to New Anti-Cancer Treatments

Clinical trials are currently underway on drugs that block the action of the telomerase enzyme. However, currently there are no drugs that specifically attack the ALT mechanism that around 15% of cancers use for their long-term survival. The development of the new test will make it much quicker to screen drugs to find those that can switch the ALT mechanism off and kill the cancer cells.

The test will allow researchers to screen thousands and possibly hundreds of thousands of chemicals to see which ones of them are effective against these particular types of aggressive cancers. The rate of searching for new anti-cancer drugs will be significantly increased, and hopefully an effective cancer treatment or cure will soon follow.

Sources:

Researchers herald cancer test breakthrough

Test may speed up war on cancer

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The copyright of the article New Blood Test Could Assist in Cancer Detection in General Medicine is owned by Jo Jackson. Permission to republish New Blood Test Could Assist in Cancer Detection in print or online must be granted by the author in writing.

New Blood Test May Provide Early Cancer Detection	A Normal Blood Sample is Used to Find DNA Circles	Invasive Surgery Often Required to Sample Tumours
Drugs can Be Screened to Attack the ALT Mechanism	Elizabeth Blackburn won a Nobel Prize for Her Work