Researchers have found a protein that helps breast cancer cells spread. The protein was found in the urine of women with aggressive breast cancer and its discovery offers the prospect of early warnings for patients.

The protein and the gene that controls it are called lipocalin 2, or Lcn2. The team at Children's Hospital, Boston, showed not only that it helps the tumors spread through the body, but can be detected in a simple urine test.

"Lcn2 is among the genes most highly associated with estrogen receptor (ER)-negative breast tumors," wrote Marsha Moses, Jiang Yang and their colleagues in the Proceedings of the National Academy of Sciences.

Estrogen-negative tumors are more difficult to treat because the widely used drug tamoxifen, and newer drugs called aromatase inhibitors, have little effect on them.

"We considered the possibility that Lcn2 might be detected in body fluids and might be associated with disease status," said the researchers.

Women whose cancer had been known to spread, or metastasize, had higher levels of the compound in their urine.

(Agencies via China Daily February 26, 2009)