I used to believe that a mammogram saved my life. I even wrote that in the pages of this magazine. It was 1996, and I had just turned 35 when my doctor sent me for an initial screening - a relatively common practice at the time - that would serve as a base line when I began annual mammograms at 40. I had no family history of breast cancer, no particular risk factors for the disease.

So when the radiologist found an odd, bicycle-spoke-like pattern on the film - not even a lump - and sent me for a biopsy, I wasn’t worried. After all, who got breast cancer at 35?

It turns out I did. Recalling the fear, confusion, anger and grief of that time is still painful. My only solace was that the system worked precisely as it should: the mammogram caught my tumor early, and I was treated with a lumpectomy and six weeks of radiation; I was going to survive.

By coincidence, just a week after my diagnosis, a panel convened by the National Institutes of Health made headlines when it declined to recommend universal screening for women in their 40s; evidence simply didn’t show it significantly decreased breast-cancer deaths in that age group. What’s more, because of their denser breast tissue, younger women were subject to disproportionate false positives - leading to unnecessary biopsies and worry - as well as false negatives, in which cancer was missed entirely.

Those conclusions hit me like a sucker punch. “I am the person whose life is officially not worth saving,” I wrote angrily. When the American Cancer Society as well as the newer Susan G. Komen foundation rejected the panel’s findings, saying mammography was still the best tool to decrease breast-cancer mortality, friends across the country called to congratulate me as if I’d scored a personal victory. I considered myself a loud-and-proud example of the benefits of early detection.

Sixteen years later, my thinking has changed. As study after study revealed the limits of screening - and the dangers of overtreatment - a thought niggled at my consciousness. How much had my mammogram really mattered? Would the outcome have been the same had I bumped into the cancer on my own years later? It’s hard to argue with a good result. After all, I am alive and grateful to be here. But I’ve watched friends whose breast cancers were detected “early” die anyway. I’ve sweated out what blessedly turned out to be false alarms with many others.

Recently, a survey of three decades of screening published in November in The New England Journal of Medicine found that mammography’s impact is decidedly mixed: it does reduce, by a small percentage, the number of women who are told they have late-stage cancer, but it is far more likely to result in overdiagnosis and unnecessary treatment, including surgery, weeks of radiation and potentially toxic drugs. And yet, mammography remains an unquestioned pillar of the pink-ribbon awareness movement. Just about everywhere I go - the supermarket, the dry cleaner, the gym, the gas pump, the movie theater, the airport, the florist, the bank, the mall — I see posters proclaiming that “early detection is the best protection” and “mammograms save lives.” But how many lives, exactly, are being “saved,” under what circumstances and at what cost? Raising the public profile of breast cancer, a disease once spoken of only in whispers, was at one time critically important, as was emphasizing the benefits of screening. But there are unintended consequences to ever-greater “awareness” - and they, too, affect women’s health.

Breast cancer in your breast doesn’t kill you; the disease becomes deadly when it metastasizes, spreading to other organs or the bones. Early detection is based on the theory, dating back to the late 19th century, that the disease progresses consistently, beginning with a single rogue cell, growing sequentially and at some invariable point making a lethal leap. Curing it, then, was assumed to be a matter of finding and cutting out a tumor before that metastasis happens.

The thing is, there was no evidence that the size of a tumor necessarily predicted whether it had spread. According to Robert Aronowitz, a professor of history and sociology of science at the University of Pennsylvania and the author of “Unnatural History: Breast Cancer and American Society,” physicians endorsed the idea anyway, partly out of wishful thinking, desperate to “do something” to stop a scourge against which they felt helpless. So in 1913, a group of them banded together, forming an organization (which eventually became the American Cancer Society) and alerting women, in a precursor of today’s mammography campaigns, that surviving cancer was within their power. By the late 1930s, they had mobilized a successful “Women’s Field Army” of more than 100,000 volunteers, dressed in khaki, who went door to door raising money for “the cause” and educating neighbors to seek immediate medical attention for “suspicious symptoms,” like lumps or irregular bleeding.

The campaign worked - sort of. More people did subsequently go to their doctors. More cancers were detected, more operations were performed and more patients survived their initial treatments. But the rates of women dying of breast cancer hardly budged. All those increased diagnoses were not translating into “saved lives.” That should have been a sign that some aspect of the early-detection theory was amiss. Instead, surgeons believed they just needed to find the disease even sooner.

Mammography promised to do just that. The first trials, begun in 1963, found that screening healthy women along with giving them clinical exams reduced breast-cancer death rates by about 25 percent. Although the decrease was almost entirely among women in their 50s, it seemed only logical that, eventually, screening younger (that is, finding cancer earlier) would yield even more impressive results. Cancer might even be cured.