US health officials have approved Hologic’s three-dimensional (3-D) mammogram system in hopes that it may help doctors better screen and diagnose breast cancer, even though women may be exposed to more radiation.

The device, an upgrade to the company's already approved two-dimensional (2-D) system, offers physicians a more detailed look at the breast to see any possible anomalies, the Food and Drug Administration said on Friday.

FDA's approval is a big win for the device maker, which some analysts have said is farthest ahead in the race to develop better technology to detect breast cancer. Siemens AG and General Electric Co also have been pursuing similar imaging tests.

Shares of Hologic, which focuses on devices for women's health, initially rose more than 3 per cent after the news before paring gains. Its shares closed up 2.3 per cent at $20.18 in Nasdaq trading on Friday.

Mammograms are the best way to find breast cancer, the FDA said in a statement, but the current limited 2-D technology requires some women to have additional testing. Reviewing an additional 3-D image helped doctors find more cancers than with 2-D images alone, it said.

Roughly 1 in 8 US women are affected by the cancer and more than 2.5 million women had a history of the disease as of 2007, according to US government figures.

However, the additional 3-D testing does double the amount of radiation given to patients and "there is uncertainty for radiation risk estimates," FDA said.

But that risk is outweighed since the more-detailed scans "improved the accuracy with which radiologists detected cancers, decreasing the number of women recalled for a diagnostic work-up."

FDA staff scientists had earlier expressed concern about the unknown effects of additional radiation with the 3-D scans.

In recent years the FDA has also launched a public campaign to reduce unnecessary exposure to radiation and to help patients keep track of the doses they receive.

In its statement, the FDA said it expects women who have both a 2-D scan and a 3-D scan to see an increase in cancer risk from the additional radiation of "less than 1.5  per cent compared to the natural cancer incidence" of breast cancer, which the American Cancer Society says is a little less than 12  per cent.

The risk would be "less than 1  per cent compared to the risk from conventional 2-D mammography alone," it added.

Despite the approval, it is unclear how doctors will opt to use the 3-D scans over current mammograms or how quickly health care providers will move to adopt and pay for the new technology.

Physicians on an FDA advisory panel that backed the device in September had applauded the system as a new tool that could better help them spot disease.

It also remains to be seen how insurers, including the US Medicare program for the elderly, will opt to cover the newer scans -- decisions that could have a major financial impact on sales for Hologic. – Reuters