Some common noninvasive tests for breast cancer aren't accurate enough to routinely replace biopsies, a government review concluded Thursday.

Current guidelines recommend that women get a biopsy — removing some suspicious cells or tissue for examination — when a mammogram suggests the possibility of breast cancer.

Yet only about one in five women getting biopsies actually has breast cancer instead of some other, benign condition. Although biopsies today often can be done using a needle, there is intense interest in finding a noninvasive alternative.

The Agency for Healthcare Research and Quality reviewed four imaging methods already on the market: MRI scans, ultrasound, PET scans and a type of nuclear medicine test called scintimammography. They're used for various breast-related purposes. MRI scans, for example, sometimes are used to help screen the denser breasts of young women that mammograms don't always penetrate. Ultrasound can distinguish when a lump is a fluid-filled cyst.

But if these tests routinely replaced biopsies, they would miss between 4 percent and 9 percent of cancer cases among women at average risk of the disease, possibly more among high-risk women, the agency concluded.