( TIME.com ) -- Good Morning America host Amy Robach revealed on her show that a recent on-air mammogram had found she has breast cancer , but the diagnosis would n't have been made if she followed certain federal guidelines for screening . Robach is 40 , and the U.S. Preventive Services Task Force , a group of independent experts convened by the government to review the risks and benefits of different screening practices , advised in 2009 that as a public health measure , the benefits of saving lives would outweigh the risks of screening if women started getting yearly checks beginning at age 50 , rather than at age 40 , as the American Cancer Society and other groups advise . The task force based its conclusion on the potential costs , both economic and emotional , of uncertain mammogram results , which would lead to follow up tests including biopsies and procedures like lumpectomies and mastectomies , most of which , the studies they investigated showed , ended up being negative . But maximizing public health and decreasing harm may be at odds with minimizing an individual woman 's risk of dying of breast cancer . And that 's the situation that `` we see every day in my field , '' says Dr. Larry Norton , a breast cancer expert at Memorial Sloan Kettering Cancer Center . `` We see real human beings getting screening mammograms so their cancer is detected at stages when we have curative treatments , '' Norton continues . `` When people talk about the downsides of screening , it does n't compute in the minds of people who are actually in contact with human beings . '' TIME.com : GMA 's Amy Robach reveals on-air test led to breast cancer diagnosis . Robach wrote on Good Morning America 's website that she has `` very little family history '' of the disease , and `` considered it virtually impossible that I would have cancer . '' She only agreed to get the mammogram live on air , at the request of her producers and colleague Robin Roberts , herself a cancer survivor . Had she followed the USPSTF guidelines , which some doctors do , and upon which some insurers base reimbursement decisions , she might not have gotten a mammogram for another decade . `` I do n't want to imagine what could have happened if she had her first mammogram at age 50 , '' says Norton of Robach 's case . And that 's why , despite the public health advice , most doctors still recommend that their patients start getting regular mammograms when they turn 40 . It 's not that they are being ornery , or stubborn to change , but that there 's a biological mandate to find potential tumors in younger women early . For one , the idea that the stage at which a cancer is detected , which has a lot to do with its size , determined a woman 's prognosis , are fading away . What truly matters is the biology of the tumor itself -- understanding how it grows , what it feeds on , and whether it 's driven by genetic factors -- is far more predictive of whether a woman will survive a breast cancer or not . `` Younger women tend to get aggressive tumors that are quicker growing and not fed by estrogen , '' says Dr. Jennifer Litton , a breast cancer specialist at MD Anderson Cancer Center . The concept of cancers growing slowly over years is more typical of older women who are past menopause than younger women in their 40s . There 's also growing evidence that in breast cancer , tumors start to send out signals to other parts of the body to prime them for metastatic growths . `` The lungs change before the first cancer ( from the breast ) gets there , '' says Norton , `` and the lungs become a fertile field so when the first cancer does get there , it 's ready to grow . And that 's a time dependent process , so the earlier you intervene , you can stop the process of metastasis . '' And once a cancer has spread , it 's much more likely to be deadly . TIME.com : Mammogram guidelines : What you need to know . Why is the USPSTF conclusion so at odds with the breast cancer care that most doctors practice every day ? Part of the problem may be that the studies the task force included involved older mammogram machines that did not provide the digital images that newer machines do , with better resolution and multiple views of the breast tissue to more accurately identify potential tumors . The task force guidelines did not rule out mammograms for women under age 50 ; women with a family history of the disease , or other risk factors such as exposure to environmental estrogens , being on the pill or drinking alcohol should talk to their doctors about starting screening earlier , the members said . The decision about when to start screening , says Litton , should really be a personalized one , made by a woman and her doctor , after factoring in her medical history . And for now , that conversation is likely to be an involved and difficult one , but will hopefully become easier as better methods for detecting the first signs of breast tumors become available . `` Screening is going to evolve , and we will have not just imaging but biologic tests such as biomarkers , '' she says . `` Would n't it be great to have a blood test , or be able to spit into a cup and then know whether you have cancer , and you would n't have to go through unnecessary biopsies ? '' Study questions benefit of yearly mammograms . That day may be coming , but it 's not here yet . In the meantime , women like Robach have to make their own decisions about when to start screening . They also have to understand that the risk factors for cancer do n't always stand up and shout and make themselves obvious . Robach decided to undergo a double mastectomy to treat her disease , and wrote that `` I got lucky by catching it early . I can only hope my story will ... inspire every woman who hears it to get a mammogram , to take a self exam . No excuses . It is the difference between life and death . '' This story was originally published on TIME.com . Why mammogram guidelines would have missed Amy Robach 's cancer . & copy 2012 TIME , Inc. TIME is a registered trademark of Time Inc. Used with permission .
Robach is 40 ; federal guidelines recommend yearly checks at 50 . Comment: Women should make their own decisions about when to start screening .