Tests to predict cancer's path

Doctors believe a new test that looks at immune cells in the lymph nodes may be the best way to predict whether breast cancer has spread and is likely to recur.

At present, the best way to predict whether breast cancer is likely to come back is to search for tumour cells in the lymph nodes near the breast.

But Dr Peter Lee and his colleagues at the Stanford University School of Medicine have found that examining the immune cells in the lymph nodes might be a better way to predict the cancer's spread and to identify patients who need extra treatment.

"Immune changes in the lymph node almost perfectly predict clinical outcome, much better than any other prognostic factor that is available today," Dr Lee said.

Writing in the journal Public Library of Science-Medicine, Dr Lee and colleagues said they tested lymph node tissue samples from 77 breast cancer patients taken more than five years ago. All of these patients suffered cancer that had spread out of the breast.

Within five years, 33 of the 77 patients had their cancer return.

Immune cells are known to sometimes destroy cancer cells - they keep cancer constantly under control in most normal healthy people. But Dr Lee was tying to find out what goes wrong when the immune system fails to control cancer.

His team looked for tumour cells and for three major types of immune cells: cytotoxic T cells, helper T cells and dendritic cells.

Lymph nodes that had been invaded by tumour cells showed dramatic decreases in helper T cells and dendritic cells. They also had fewer cytotoxic T cells, Lee found.

"Then we found something more interesting and puzzling," Dr Lee said.

Even in some lymph nodes that had only a few tumour cells, or no tumour cells, the immune cell balance was off.

For the most part, this imbalance in immune cells was seen in the 33 women whose breast cancer came back before five years.

"It was a surprise to find immune changes in lymph nodes with no detectable tumour cells," said Dr Lee.

Perhaps tumour cells secrete some substance that prepares the lymph node for invasion, he said.

"Even before it actually invades the node, it actually causes the node to change."

The women whose lymph nodes had a normal immune cell balance had an 85 to 90 per cent chance of being disease-free after five years. The group with an "unfavourable" immune profile had less than a 15 per cent chance.

Dr Lee is developing a simple test to determine which women could benefit from more aggressive therapy, and which could be spared undergoing costly and toxic treatments unnecessarily.

- REUTERS