At the end of New York State’s legislative session two weeks ago, a bill mandating insurers to pay for tomosynthesis, also known as 3-D mammography, passed the Senate, the last hurdle before reaching the governor’s desk. In truth, the bill had no hurdles. No dissenting votes – not in the Senate or in the Assembly, which approved the measure last March. We’ve known for a long time that cancer screening makes for good politics and this latest tale shows how easily good science, or at least the best there is at the moment, is shoved aside in favor of dubious and costly medical interventions that are crowd pleasers at the ballot box.

Tomosynthesis has a history in New York. In March, New York Gov. Andrew Cuomo sent out a news release announcing he had taken action “to expand cutting-edge breast cancer screening options for women.” What New York woman wouldn’t have been delighted by that news? However, the Affordable Care Act already required insurers to cover breast cancer screening, and the New York Health Plan Association, the insurers trade group, said its members already were paying for medically necessary 3-D screenings.

Last year the New York State Legislature passed a bill removing financial barriers to breast cancer screening, forbidding insurers from imposing deductibles and coinsurance for such exams. So Cuomo’s February announcement merely reaffirmed what state law already mandated. It hardly qualified as news. And yet the glowing media coverage made it sound like a brand new benefit was on the way.

However, the most recent June vote by the legislature does elevate breast cancer screening to another level. It cements into law the requirement for insurers to pay for the high-tech approach regardless of medical necessity, “setting up 3-D mammography as a front line screening tool,” says Leslie Moran, senior vice president of the New York Health Plan Association. The bill makes no mention of the usual considerations for screening decisions, such as a patient’s family history or dense tissue or her doctor’s recommendation, all things which might make the high-tech 3-D approach medically necessary. Instead, the bill effectively adds 3-D screening “as a routine procedure for all women,” as Bill Hammond wrote in a blog post for the Empire Center for Public Policy, a conservative think tank in Albany.

Medical evidence changes faster than laws

Codifying screening procedures in law is dangerous business because the science supporting medical tests can change. Take Pap smears. The U.S. Preventive Services Task Force (USPSTF) once recommended yearly Pap tests, but now calls for screening every three years in women ages 30 to 65. New York State law still requires insurers to cover annual tests for women in this age bracket.

New York is about to ignore the science once again. The USPSTF made clear that evidence is lacking for 3-D mammography to be considered a medical necessity in many of the very cases where its use is promoted or prescribed. It made no specific recommendation for 3-D testing, saying that it was not clear that the new technology will result in improved health, better quality of life, or fewer deaths.

I rang up H. Gilbert Welch, MD, a professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice and an expert on cancer screening. If the best test is judged to be the one that finds the most cancers, he said, then it’s “a recipe for overdiagnosis.”

“The best test is the one that finds the cancers that are really going to matter,” according to Welch. Some small tumors grow so slowly that they may never cause symptoms. “The goal is not to find as much cancer as possible,” he said, and cited the overtreatment of thyroid and prostate cancer. In a study on the overall effectiveness of mammography screening reported in the New England Journal of Medicine late last year, Welch and colleagues concluded, “Women were more likely to have breast cancer that was overdiagnosed than to have earlier detection of a tumor that was destined to become large.”

When it comes to state coverage mandates, science and evidence are pushed to the rear. “Every time I pick up a mandate bill and look closely at it, I find they ignore what the experts say,” Hammond told me. “There’s a perverse political logic behind them. As much as people say they care about the evidence and science, they act on emotion and want to help people who are sick.”

Who benefits from mandates?

However, those helped the most by healthcare legislation often are the ones selling the mandated technology or intervention. The case for 3-D mammography is no exception. Two groups that lobbied for the bill were Memorial Sloan Kettering Cancer Center, the premier cancer hospital in New York City, and the New York State Radiological Society. Both organizations will benefit financially if 3-D mammography becomes a first-line screening tool. The hospital sent a memorandum to the legislature saying it “strongly supports requiring insurers to include digital breast tomosynthesis as a covered benefit,” and argued the technology “has proven to be particularly effective in reducing the number of callbacks in women with dense breasts.” The independent U.S. Preventive Services Task Force says otherwise. It reviewed the evidence for 3-D mammography for effectiveness in screening women with dense breasts, and concluded: “Unfortunately many important questions remain.”

The New York bill appears to have come from the hospital itself. According to Our Town, a local newspaper covering the Upper East Side of Manhattan where Memorial Sloan Kettering is located, “the hospital first approached Seawright” – Assembly member Rebecca Seawright – “about the possibility of authoring a bill.” After the bill passed the Assembly and the Senate, Seawright’s news releases quoted Dr. Elizabeth Morris, chief of the hospital’s breast imaging service: “This legislation means that women will have access to this potentially life-saving cancer screening.” The news releases did not mention anything about the technology potentially leading to more unnecessary treatment.

The American Cancer Society Cancer Action Network in New York took no position on the legislation because, spokesperson Marc Kaplan told me, “Our guidelines do not address the 3-D mammography.” When the protocol for the evidence review was developed, he says, there was not enough data to compare 3-D with 2-D mammography.

Society bears the costs, women suffer the harms

New York insurers opposed the measure on the basis of costs and thin evidence. In a memorandum of opposition, they noted that 3-D mammography “is significantly more expensive than traditional mammography” and that no evidence supports its replacement of traditional mammography as front line screening. In February I asked one of my insurance sources to estimate how much 3-D mammography adds to the cost of screening. He ran some numbers for the New York and New Jersey region, already notorious for high healthcare costs, and told me the cost of tomosynthesis could increase the cost of getting a mammogram in hospital settings by slightly more than one-third.

None of that mattered as the 3-D mammography bill spun through Albany’s sausage grinder as far as I could determine. Except for Bill Hammond’s critique on the Empire Center blog, a Politico New York email newsletter citing Hammond’s story, and the puff piece in Our Town, the media spotlight did not shine.