'New' estrogen receptor found to be key player in tamoxifen ...(unclear whether tamoxifen is very effect...)

Invasive lobular carcinoma, which accounts for 15 percent of newly diagnosed invasive breast cancers diagnosed each year, appear under the microscope as long, very thin tumors actually a single stream of cancer cells that line up in a row. That makes them much harder to diagnose than the more common cancer type, invasive ductal carcinoma, in which tumors form more discrete lumps.

But what the researchers found in invasive lobular carcinomas the specific cancer they studied - may also be true of tamoxifen resistance in other cancer types," she said "No one has looked for gamma estrogen-related receptors in tamoxifen resistance in invasive ductal carcinoma."

In addition to its use as a cancer preventive, tamoxifen is approved to treat both early and advanced breast cancer that is estrogen-receptor positive. (Estrogen-receptor positive cancer means that estrogen is the primary fuel that promotes cancer development and growth.) Tamoxifen binds to the estrogen receptors (alpha) that stud tumors and other breast tissue, not allowing estrogen to latch on and turn on a program of growth inside the cells. But it is estimated that 30 to 50 percent of breast cancer patients eventually become resistant to tamoxifen.

"The magnitude of this health issue is huge. More than 178,000 women will be diagnosed this year with invasive breast cancer, and 70 percent of them will have estrogen receptor-positive tumors," Riggins says. "It is clear that we need to understand why this resistance occurs."

"This is a very nice story of tamoxifen resistance in a somewhat under-investigated group of breast cancers," says the study's senior investigator, Robert Clarke, Ph.D., professor of oncology, physiology an
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