According to the American Cancer Society, lobular breast cancer accounts for about 10-percent of invasive breast cancer.

Lobular breast cancer is often known as the "sneaky" breast cancer because it is difficult to detect. This type of cancer is often diagnosed in advanced stages and is hormone-positive. Lobular breast cancer can be treated with hormone-based therapies, such as tamoxifen (Nolvadex), if caught early.

Experts believe the incidence of lobular cancer rose by 52-percent in the United States between 1987 and 1999, and the cases of ductal-lobular breast cancer rose by 96-percent during that time.

Rates of ductal cancer rose three-percent over the same time. Many believe the widespread use of hormone replacement therapy (HRT) could have played a role.

Many people are familiar with the results of the 2002 Women's Health Initiative study, which found HRT could raise the risk of breast and ovarian cancers, strokes and other serious conditions. Despite these findings, doctors estimate about 57 million prescriptions for menopausal HRT are filled each year in the United States.

Many menopausal women use the therapy to relieve the severe symptoms that accompany menopause. Some of these symptoms may include hot flashes, mood swings and urinary problems.

New findings from the Fred Hutchinson Cancer Research Center in Seattle reveal HRT can raise the risk of lobular breast cancer by four-fold in just three years. Researchers found women who took combined estrogen/progestin HRT for three years or more had this increased risk.

Previous research indicated that five or more years of combined HRT were necessary to increase overall breast cancer risk. This was the first study specifically designed to evaluate the relationship between combined HRT and lobular breast cancers.

John Link, M.D., a breast oncologist from Orange Coast Memorial Medical Center in Fountain Valley, Calif., suggests women talk with their gynecologist or primary physician about these new findings.

He says women with serious symptoms should consider the lowest dose possible of combined HRT for the shortest time and then get off slowly. He also says estrogen without progesterone does not increase the risk of breast cancer but may increase the risk of uterine cancer. "It's a bit of a double edge," Dr. Link said.