One in three women with breast cancer detected by a mammogram is treated unnecessarily, because screening tests found tumors that are so slow-growing that they are essentially harmless, according to a Danish study published Monday in Annals of Internal Medicine, which has renewed debate over the value of early detection.
The study raises the uncomfortable possibility that some women who believe their lives were saved by mammograms were actually harmed by cancer screenings that led to surgery, radiation and even chemotherapy that they didn’t need, said Dr. Otis Brawley, chief medical officer of the American Cancer Society, who wrote an accompanying editorial but was not involved in the study.
Researchers increasingly recognize that not all breast cancers pose the same risk, even if they look the same under a microscope, Brawley said. While some early tumors turn into deadly monsters, others stop growing or even shrink. But assuming that all small breast lesions have the potential to turn deadly is akin to “racial profiling,” Brawley wrote in his editorial.
“By treating all the cancers that we see, we are clearly saving some lives,” Brawley said in an interview. “But we are also ‘curing’ some women who don’t need to be cured.”
Although experts such as Brawley have long discussed the risks posed by“overdiagnosis,” relatively few women who undergo cancer screenings are even aware of the debate.
The American College of Radiology, which strongly supports breast cancer screenings, acknowledges that mammograms lead some women to be treated unnecessarily, but said the problem is much less common than the new study suggests. Another study from Denmark whose national health program keeps detailed records estimated the over-diagnosis rates at only 2.3 percent.
Treating women for cancer unnecessarily can endanger their health, said Fran Visco, president of the National Breast Cancer Coalition, an advocacy group. Radiation can damage the heartor even cause new cancers. Visco notes that breast cancer activist Carolina Hinestrosa, a vice president at the coalition, died at age 50 from soft-tissue sarcoma, a tumor caused by radiation used to treat an early breast cancer.
Women should understand these risks, Visco said. Instead, women often hear only about mammograms’ benefits.
“Women have been inundated with the early detection message for decades,” Visco said.
The risks of over-diagnosis and false positives, which can lead women with benign growths to undergo biopsies and other follow-up tests, have caused some experts to reevaluate breast cancer screenings. Although mammograms don’t find all tumors, they reduce the risk of dying from breast cancer by 25 percent to 31 percent for women ages 40 to 69, according to the Agency for Healthcare Research and Quality, part of the Department of Health and Human Services.
Medical groups now offer differing advice on mammograms:
- The American College of Radiologytakes the most aggressive stance, recommending annual mammograms beginning at age 40. Tumors should be found when they’re “smaller and easier to treat,” Monticciolo said.
- The S. Preventive Services Task Force, an independent expert panel that advises the federal government on health, provoked a firestorm of criticism in 2009 when it bucked that advice, recommending that women get mammograms every other year beginning at age 50. The group noted that breast cancer risk rises with age, so mammograms are more likely to discover cancer — as opposed to benign growths — after age 50.
- The American Cancer Society also scaled back its screening advice in 2015, recommending women get annual mammograms from 45 to 54, followed by screenings every other year after that.
Source : CNN