A less invasive method of breast biopsy appears to be nearly as effective as open surgical ones to determine if a growth in the breast is cancerous, according to a report issued this month by a government-convened panel.

With 70 to 80 percent of all breast biopsies never leading to a cancer diagnosis according to recent estimates, sparing women the expense and risks of open surgical procedures without letting potentially deadly cancers slip by would be welcome news.

The expert panel, assembled by the U.S. government's Scientific Resource Center for the Agency for Healthcare Research and Quality (AHRQ), looked at over 107 studies from December 1990 to September 11, 2009, covering some 57,099 breast lesions.

The team found that imaging-guided core-needle biopsies, which use a hollow needle to extract tissue samples from lesions instead of requiring full surgery, were extremely sensitive, that is, they missed few cancers. The exact sensitivity rate depended on the kind of core-needle biopsy performed. Biopsies guided by ultrasound or stereotactic mammography, and using an automated needle gun or a vacuum biopsy device to help suction up tissue, reached 96.5 to 99.2 percent sensitivity.

This accuracy is in line with open surgical rates. Although they were not directly examined in the government study, the panel estimates sensitivity for open surgical biopsies to be around 98 to 99 percent.

But the panel did voice some qualms with the results. Although in order to be included the studies had to meet several criteria, such as having more than 10 patients and retaining more than half of them until the end of the trial, the panel believes the overall evidence quality was low, and wants to see more research.

But Wendie Berg, M.D., Ph.D., a radiologist at Johns Hopkins Green Spring in Baltimore, MD, who also served as a consultant for the report, confirms the accuracy of core-needle biopsy is extremely high.

"The absolute miss rate for cancer, that is when we obtain a benign (noncancerous) diagnosis and think we're done, is less than 1 percent," she tells DOTmed News. "We usually know it when we haven't gotten an answer that's reliable."

Cancer underestimations

The government's study does take into account a known wrinkle with core-needle biopsies. Occasionally, the biopsies will mischaracterize invasive cancers as a noninvasive growth, such as ductal carcinoma in situ (DCIS) or high-risk atypical ductal hyperplasia (ADH). However, these occasional underestimations do not affect the procedure's sensitivity rating because under current clinical practice these growths are almost always removed if detected, as in almost one-fifth of cases they can coexist with a more severe condition.

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