By Victoria Vaughan

A BIOCHIP which sieves cancer cells from the blood has been developed by a team of mechanical engineers from the National University of Singapore.

Capturing the cells without damaging them - a feat considered very difficult until now - allows doctors to study the cancer and see how the disease has progressed.

After passing just two teaspoons (10ml) of blood through the micro device, experts can count the number of cancer cells in the blood stream through a microscope and collect the cancer cells for further tests.

Other methods of capturing such cells involve magnetic separation and protein-coated collection devices, which can destroy them in the process.

Cancer cells are found in the bloodstream when a cancer is malignant - the aggressive type of cancer.

They are not easy to isolate however, as 1ml of blood contains about five billion red cells and 7.4million white blood cells, but only five or fewer cancer cells, in the early stages of illness.

These cancer cells detach from the cancer and travel in the bloodstream, attacking other parts of the body to form more tumours.

The new device, one-third the size of a five-cent coin (5.1mm by 3.7mm), is creating a stir in the cancer research field. It has already bagged its inventor, doctoral student Tan Swee Jin, a merit prize in the Tan Kah Kee Young Inventors Awards this year.

Mr Tan, with his supervisor Professor Lim Chwee Teck, came up with the tiny microfluidic device containing 900 crescent- shaped cell catchers to isolate the cancer cells.

While white and red blood cells are malleable enough to squeeze through the net, the stiffer cancer cells get caught.

The 29-year-old said the challenge had been to avoid clogging the biochip with unwanted blood cells or damaging the cancer cells.

Prof Lim, who is with the Engineering Faculty's department of mechanical engineering and division of bioengineering, is the co-inventor.

He explained that counting the cancer cells can show doctors how advanced the cancer is. By comparing cell numbers before and after treatment, doctors can also see if the cancer is being beaten.

The cells captured by the device could perhaps one day spell the end of often painful cancer biopsies - a test involving the removal of tissue of cells for testing, he added.

Tests have shown the device captures 80 per cent of the cancer cells present.

The National Cancer Centre Singapore is keen to commence preliminary patient trials with it, and has applied for a grant with the National Medical Research Council.

This article was first published in The Straits Times.