Biomarker that may predict breast cancer more effectively identified

November 14th, 2007 - 8:35 am ICT by admin  
The study was conducted at the University of Cincinnati and was funded by rants from U.S. Department of Defense Breast Cancer Program and the UC cancer research program.

According to the researchers the elevated levels of three standard molecules responsible for tumor growth in the breast were estrogen receptor (ER), progesterone receptor (PR) and HER2-are used as “biomarkers” for diagnosis and individually detect only a fraction of breast cancers.

“The problem with these biomarkers is that many of them are present at some level in the normal breast,” said Georg Weber, MD, PhD, lead investigator of the new study and associate professor of pharmacy at the University of Cincinnati.

“In addition, they are surface molecules that support growth so they are not necessarily a good predictor of tumor metastasis,” he added.

The study also identifies a molecule, osteopontin-c, that is absent from the normal breast and identifies breast cancer that will become metastatic and spread to distant organs from the original tumor site.

In normal levels, osteopontin is a protein used by the immune system to help cells move and migrate. There are three forms of osteopontin-a, b and c-which are formed by splicing, or “cutting and pasting,” ribonucleic acid (RNA) molecules to make variations of the original gene.

Osteopontin-a is the normal form that helps with immune functions. Little is known about osteopontin-b, but if present its levels are very low. Osteopontin-c is the molecule Weber and his team discovered is a good biomarker of breast cancer.

In a two-year evaluation of 178 breast tumors, normal and abnormal tissue samples, they found that osteopontin-c was present in 78 percent of cancers and in 36 percent of the surrounding tissues. It was not detected at all in normal tissues.

In 56 breast cancers, 20 were positive and 36 were negative for estrogen receptor, 19 were positive and 37 were negative for progesterone receptor, and 26 were positive for HER2 with 30 negative.

“Osteopontin-c was present in a substantially higher number of breast cancers than the three biomarkers traditionally used to diagnose breast cancer,” said Weber.

“We also found that the cancers containing osteopontin-c correlated with a higher tumor grade, meaning they were more likely to become aggressive cancer

“If we know that this molecule is not present in a patient with breast cancer, it’s more likely that we can treat them with conservative therapy rather than breast surgery, hormone therapy or chemotherapy because we know it’s less likely to metastasize

“On the other hand, if we know that a patient has this molecule early in their diagnosis, we can treat it more aggressively because we know their cancer is likely to become invasive,” he added.

The study was published in latest October issue of an early online edition of the International Journal of Cancer. (ANI)

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