Yesterday, in a move being described as “a major shift,” the American Cancer Society changed its guidelines on when and how often women should undergo professional physical exams and mammograms for breast cancer.

Under previous guidelines that the organization had trumpeted for years, women “of average risk” were to begin both at age 40 and repeat them every year. Now the ACS is recommending annual mammography start at age 45, cutting back to once every two years at age 55, and eliminating the screen altogether when a woman’s future life expectancy falls inside of 10 years. As for the physical exam, the ACS no longer recommends it at all.

The reason for the change is that both screens provide so many stressful false positives that the ACS doesn’t believe regular testing passes a cost-benefit test unless the woman is of “higher than average risk.”

The shift should be welcome news for women. Mammograms and doctor breast exams are charitably described as “uncomfortable,” and probably more accurately described as “painful and embarrassing.” But the ACS change could become painful and embarrassing for the architects of the 2010 Patient Protection and Affordable Care Act (ACA).

One of the most scrutinized provisions of the ACA is the creation of the Independent Payment Advisory Board (IPAB), whose ostensible job is to recommend cost-containment measures if Medicare expenditure projections begin to outpace a previously determined growth rate. In reality, IPAB is to monitor the cost and effectiveness of various types of care to determine which will be covered by Medicare, with the expectation that those decisions will serve as a template for private health insurers and other third-party payers. The hope is that IPAB’s decisions will eliminate coverage of procedures that don’t measure up, thereby “bending the cost curve”—that is, reducing the nation’s overall spending on health care.

IPAB has been derided by critics as a “death panel” that could eliminate crucial care, and criticized by more thoughtful scholars as an unaccountable rationing board that will inject itself in decisions that ought to be private. In contrast, I’ve argued that IPAB is more likely to be a paper tiger that may occasionally block some treatment or another, but will usually cave to political pressure and approve popularly appealing procedures and treatments that pass no reasonable cost-benefit test. Those decisions will then pressure third party payers to also cover the care. That way, IPAB will bend the cost curve—just in the opposite direction from what the ACA writers intended.

So think of the ACS shift as a looming test of IPAB, as not-recommended breast cancer screenings are exactly the sort of Medicare expenditure the board should identify for elimination. So far, the “projected expenditures” provision for the board (or the secretary of health and human services, acting in IPAB’s stead) has not been triggered, so no cost-containment recommendations are currently forthcoming. Thus give IPAB an “incomplete” on this test for now—but don’t expect a good grade later.