Sources:  Harvard School of Public Health, Annals of Internal Medicine online, BBC Health News

Harvard School of Public Health (HSPH) research suggests that routine mammography screening, the current essential tool in detecting early breast cancers, may lead to a significant amount of overdiagnosis of disease that would otherwise have proved harmless.

The researchers analyzed data from 39,888 women with invasive breast cancer in Norway, 7,793 of whom were diagnosed during the 10-year rollout of the Norwegian Breast Cancer Screening Program, which began in 1996, (women ages 50 through 69).  Given the size of the study, researchers were able to compare the number of breast cancer cases in women who had been offered screening with those not offered screening.  The working theory was if mammography is beneficial, it would lead to a decrease in late-stage breast cancer cases, or early detection prevents late-stage disease.

But the researchers did not find a reduction in late-stage disease in women who’d been offered screening.   Instead, there was a substantial amount of overdiagnosis.  Of 7,793 women diagnosed with breast cancer through participation in the screening program, 15% to 25% were overdiagnosed (1,169 – 1,948 women).  Accordingly, for every 2,500 women undergoing early screening, 2,470 to 2,474 will never be diagnosed with breast cancer and 2,499 will never die from breast cancer.  The projected result is that for the 1 death prevented, 6 to 10 women will be overdiagnosed, and treated with surgery, radiation therapy, and possibly chemotherapy without any benefit.

“Mammography might not be appropriate for use in breast cancer screening because it cannot distinguish between progressive and non-progressive cancer,” said lead author Mette Kalager, a visiting scientist at HSPH and a researcher at the Telemark Hospital in Norway.   Most women in the U.S. begin having annual mammograms in their 40s or 50s.

Dr Julie Sharp, Cancer Research UK’s senior science information manager, was quoted as saying: “Women need more accurate, evidence-based and clear information to be able to make an informed choice about breast screening. The decision whether to be screened is a personal one and that decision should be made with all of the potential harms and benefits fully explained.  “Until we have the results of the review, Cancer Research UK’s position is that we remain supportive of breast screening.”

If nothing else, the new findings suggest that women should be well-informed not only about the potential benefit from mammography, but also about its possible harms—including mental distress, biopsies, surgeries, or chemotherapy and hormone treatments for disease that would never have caused symptoms.

For more information, see: “Overdiagnosis of Invasive Breast Cancer Due to Mammography Screening: Results From the Norwegian Screening Program,” Mette Kalager, Hans-Olov Adami, Michael Bretthauer, Rulla Tamimi, Annals of Internal Medicine, online April 2, 2012.

If you or a loved one have been diagnosed with breast cancer which could have been found earlier, contact the Lewis Law Firm attorneylewis.rn4.internetrnd.com to determine if you have a medical malpractice claim.  The Lewis Law Firm has a long history of representing breast cancer patients and their family members in Pennsylvania and New Jersey.

Posted by: Gayle R. Lewis, Esquire