THURSDAY, Nov. 9, 2006 (HealthDay News) -- A particular estrogen receptor (GPR30) found on breast tumor cells is a predictor of tumor size and aggressiveness, U.S. researchers report.
The findings may have an impact on treatment decisions involving hormone therapy, said researchers at Rhode Island Hospital and Brown Medical School.
"We found that a novel estrogen receptor, termed GPR30, is linked to breast tumor progression and increased tumor size," study author Edward J. Filardo, a research associate at Rhode Island Hospital and assistant professor at Brown Medical School, said in a prepared statement.
"Furthermore, the results support prior research suggesting that GPR30 acts independently from the two known estrogen receptors, ERfN and ERfO," he said.
Estrogen attaches to receptors on breast cancer cells and transmits signals that instruct the cancer cells to grow and multiply. Doctors test for estrogen receptors to determine the best treatment approach for breast cancer patients. Typically, the more estrogen receptors there are, the better a patient will respond to hormone therapy.
Reporting in the Nov. 1 issue of Clinical Cancer Research, Filardo and his colleagues analyzed 361 breast tumor samples.
They found that GPR30 was positively associated with tumor size and that primary tumors from patients with metastatic cancer were twice as likely to express GPR30.
The researchers also concluded that GPR30 expression was autonomous from that of standard estrogen receptors.
"It strengthens the concept that GPR30 and standard estrogen receptors promote distinct biological responses, and invokes a new paradigm regarding our current understanding of breast cancer biology," Filardo said.
The American Cancer Society has more about breast cancer.