Welcome to the first part of an 11-part serial on breast cancer in Marin County. This investigation began more than five years ago, when science journalist Peter Byrne encountered a startling fact: 10 percent of all mammograms produce false positives.

A longtime Bay Area resident, Peter had for years read headlines declaring Marin County the breast-cancer capital of the world. Then he began to dig. He found that high rates of breast cancer screening explained the so-called cancer cluster in Marin.

Peter read hundreds of scientific papers and talked with dozens of experts in an effort to understand where the myth began and how it has funded decades of biased research. To make the science underlying the problem understandable to the public, he studied epidemiology textbooks.

At the end of last year, ready to start writing, Peter came to me. We launched a Kickstarter campaign to supplement a grant from the Fund for Investigative Journalism, and for the last several months we’ve been whittling down his research into these 10 parts, which we will publish weekly. In part nine we will report on how officials at the California Department of Public Health tried to kill the story.

The first part, Renée Willard’s story, introduces the series and describes one woman’s journey from an uncertain cancer diagnosis to a mastectomy, and her disturbing discovery of the state cancer registry’s flawed record of that journey.  — Tess Elliott, Editor and Publisher, Point Reyes Light



Renée Willard won her doctorate in pharmaceutical chemistry at the University of California, San Francisco, in 1995. Her lab studied how estrogen and breast cancer cells interact. Though she did not solve one of the key riddles in breast cancer research, Dr. Willard did learn how the choice of what to research is constrained by money.

“If the tool in hand is a hammer, you design experiments that require a hammer,” she quipped in an interview at her Mill Valley home last winter.

After working in public health in San Francisco for many years, Dr. Willard moved across the Golden Gate to wealthy, bucolic, liberal Marin County to take up a new career. In the back of her mind stirred years of exposure to media headlines declaring that white women living in Marin are targeted by breast cancer.

“I took it for granted that the cancer cluster claim was true,” she said.

Not one to tempt fate, she obeyed the smiling women pictured on mailers sent by her H.M.O., warning her that failing to get a mammogram by age 40 was both dangerous and irresponsible.

At age 42, Dr. Willard received her second breast X-ray. A month before Christmas, she got a phone call from her insurance provider telling her there was “a suspicion of malignancy.” Alarmed, she underwent a biopsy.

“I lay on my stomach on a hydraulic table that pinned me six inches from the ceiling,” she recalled. “Below me, the X-ray machine guided a needle that drilled into my left breast and extracted several cores.”

Shortly after Christmas, the H.M.O. rang again: “You have breast cancer,” she was told. Dr. Willard recalls thinking, “I’ve only lived in Marin for two years, and now I am one of those women.”


The unseen stalker

For nearly three decades, affluent white women in Marin have lived with the fear that they are more at risk of breast cancer than are less socially advantaged women elsewhere. The media regularly stokes their anxiety.

In 2002, the San Francisco Chronicle headlined, “Unseen Killer Stalks Marin.” A year later, the publication proclaimed, “Breast Cancer Amid Affluence: High Rate in Marin County Appears Tied to Wealth, Education.” Ten years later, the Chronicle was still beating the drum: “Bay Area Breast Cancer Clusters Seen.”

KQED echoed, “Local Breast Cancer Clusters Seen.” The Huffington Post weighed in with “Marin County Breast Cancer Study Reveals Shockingly High Rate of Disease.” According to a 2013 Marin Magazine article, the county has long been known as “the breast cancer capital of the world.”

The problem with all this reporting is that there never was an epidemic of breast cancer targeting affluent white women in Marin.

“The breast cancer incidence rate in Marin is no different from the rate in any demographically comparable suburban area, such as Long Island,” Michael Lagios, a nationally renowned pathologist based in Tiburon, told the Light. “Go to the Marin Symphony and look around: you will see a sea of white heads. Marin has the oldest average age of any county in America. It is full of older, wealthy, educated women with great access to medical care and mammography, which results in a higher frequency of breast cancer detection.”

Age is by far the greatest risk factor for breast cancer. But the high incidence rate in Marin is only partially attributable to seniority, since incidence rates are adjusted for age differences between localities. Data show that women of all ages living in Marin get substantially more mammograms than do women in lower-income communities.

There is not more breast cancer in Marin than elsewhere, experts say; rather, it is detected more frequently—and often erroneously, as this investigation found.

Over the decades, the persistent belief that wealthy white women are more at risk of breast cancer has skewed research priorities and undermined the effectiveness of public health activities around the nation. In Marin, the county health department excluded non-white women from most of its studies on breast cancer causation and bypassed data disproving its conclusions. This series explains the how, where, what and when of a story that never should have happened.


The problem with mammograms

The widespread belief in a Marin breast cancer cluster is rooted in decades of epidemiological studies published in medical journals by researchers at the Cancer Prevention Institute of California, a Fremont-based nonprofit. The institute runs the Greater Bay Area division of the California Cancer Registry, a statewide agency funded by the California Department of Public Health.

According to the registry, which is tasked with collecting data on all cancer cases diagnosed in California, “Breast cancer rates are higher among white women than among women of other races. They also tend to be higher among women with higher socioeconomic status. Therefore, we would expect to find higher breast cancer rates in communities with many affluent white women than in other communities with a different racial and socioeconomic mix.”

The American Cancer Society’s 2014 report on California is slightly more circumspect: “For reasons that are not completely understood, being well-educated and financially well-off are associated with a higher risk of developing breast cancer. Non-Hispanic white women in the highest socioeconomic status are at the highest risk.”

During the past quarter-century, scientists at the Cancer Prevention Institute and other Bay Area institutions have spent millions of public dollars studying why breast cancer disproportionately targets white women living in Marin and other suburban enclaves. Biological, environmental and lifestyle choices have been put forth as possible causes.

Remarkably, a circle of co-authoring epidemiologists at the Cancer Prevention Institute, the Novato-based Buck Institute for Research on Aging, the University of California, San Francisco, and Marin Health and Human Services treats the hypothesis that breast cancer preferentially attacks affluent white women not as theory, but as non-controversial fact.

Experts outside that circle, however, say that Marin’s high incidence rate is a statistical anomaly caused by sociological factors.

Olufunmilayo Olopade is an internationally renowned expert in cancer risk assessment and the director of the Center for Clinical Cancer Genetics at the University of Chicago. At the Light’s request, Dr. Olopade reviewed the major studies on breast cancer incidence rates published by the Cancer Prevention Institute. She strongly disagreed with the institute’s theory that affluent white women in Marin, or anywhere else, are more vulnerable to the disease.

“People who utilize medical services the most are going to be diagnosed with more diseases,” she said. “Because people with insurance get the most mammograms, a cancer registry’s breast cancer incidence reporting will be skewed toward people with access to good health care services.”

Michael Hogarth of the Department of Pathology and Laboratory Medicine at the University of California, Davis, agreed. “Higher socioeconomic status translates into better access to mammograms and clinical cancer screening, and more diagnosis of breast cancer,” he told the Light.

Dr. Hogarth is quick to add that the widespread use of screening mammography has greatly increased the number of breast cancer diagnoses without decreasing mortality rates over time. As otherwise healthy women are screened, increasingly sensitive technologies are finding indolent cancers—microscopic, non-lethal cellular abnormalities that do not require treatment, but which are most often treated anyway.

Mammograms also generate large numbers of false positive readings; the more screenings a woman gets, the more likely she is to be called back for a second mammogram or to be falsely diagnosed with cancer. For Dr. Hogarth and others, overdiagnosis calls into question the efficacy of screening as a public health strategy.



Dr. Willard’s diagnosis was “ductal carcinoma in situ,” or D.C.I.S. The good news was that though her biopsied cells were abnormally shaped, they were not necessarily life-threatening. (D.C.I.S. is not a cancer tumor, despite the carcinoma label.) The bad news was that the size and distribution of cells inside the duct could have signified the presence of dangerous cells that might one day escape and spread disease.

Her doctors advised her to “move fast” to have a “breast conserving” lumpectomy and radiation treatment. They did not offer other options. Not wanting to wait and see if the oddly shaped cells infiltrated the surrounding tissue, Dr. Willard decided to undergo the lumpectomy.

A surgeon excised the region containing the abnormal cells shortly after Christmas. Dr. Willard reacted poorly to the anesthesia and woke up sick and disoriented from the outpatient operation, only to be handed a glass of water and a cracker and ushered out the door.

Two weeks later, the surgeon pronounced her a “cancer survivor.”

“I thought, ‘What the hell, I did not survive anything. I’ve had ‘cancer’ for three weeks,’” Dr. Willard said. “It made no sense to me to jump on the happy pink-ribbon bandwagon that the H.M.O. steered me toward.”

Being a survivor did not mean she could skip radiation, and before going under the beam, she was required to have another mammogram. The X-ray produced microscopic white spots in the same breast that had undergone the lumpectomy.

She was told she may no longer be cancer-free.


Explaining overdiagnosis

Overdiagnosis is commonly defined as a diagnosed condition that does not result in symptoms or death. Screening mammography primarily looks for circumstantial evidence of breast cancer in the pre-clinical phase, before it can be detected by palpitation or symptoms. It does not prevent cancer, and its efficacy can only be tested by conducting decades-long, randomized clinical trials that correlate death rates with the detection of cellular abnormalities by screening programs.

Prior to the advent of mammography, D.C.I.S.—a condition often mistaken for true cancer—was an unknown malady. Its presence cannot be felt by hand or seen by the naked eye. On the mammographic film or digital display, cancerous and non-cancerous collections of cells can look the same, since both can block the trajectory of X-rays, leaving behind nodules of microscopic white dots against the darker background of the light-catching medium. These spots can signify the presence of cells killed by cancer, but they can also signify the presence of clusters of abnormally shaped cells that are not destined to morph into cancer. It is extremely difficult for radiologists to distinguish between them.

Correctly labeling cells as cancerous requires as much art as science on the part of a medical practitioner. Overdiagnosis not only leads to painful treatments for indolent cancers, but to the labeling of non-cancers as cancers in data bases.

The inclusion of false positives inflates the actual numbers of cancers recorded, and this has proven especially true for breast cancer. There is a roughly 10 percent chance that a doctor will incorrectly interpret a mammogram as positive for invasive or non-invasive cancer. By the time a high-risk woman has her ninth mammogram, a false positive diagnosis is almost certain to have occurred. This means that over 10 years of annual screening, more than half of the women screened will receive a false positive. Some of these errors are caught before a patient is treated, but some are never caught. (Biopsies have high false positive rates, too.)

And once a case is treated as a cancer, it is recorded by a registry as a cancer.


The danger of breast density

Like many pre-menopausal women, Dr. Willard’s breast tissue was “dense,” meaning the ratio of milk ducts and lobules to fat in her breast was higher than average. Women with denser breasts experience a higher rate of false positive mammograms than do women with less dense, more fatty breasts. This is because the solidity of milk-making structures relative to less dense tissue obstructs the penetration of X-rays, causing clusters of white spots on a mammogram. These spots resemble the photon-deflecting “calcifications” (dead cells) associated with cancer.

Dense breasts can also hide the presence of active cancer cells from X-ray beams, which increases the risk of a true cancer developing. So although women with denser breast tissue are not known to be biologically more susceptible to cancer, the presence or absence of disease is harder to detect in their tissues.

D.C.I.S. is also a “switch hitter,” since in some cases the abnormal cells transform into super-proliferating cancer cells that metastasize into the blood stream. More often than not, however, the abnormal cells stay in place, trapped inside ducts and lobules.

Because medical science cannot distinguish between an oddly shaped cell that will remain benign and an out-of-control cell that is destined to invade tissue, the standard of care is to treat abnormalities as if they are invasive carcinomas.



Dr. Willard’s second biopsy wasn’t successful in reaching the suspect area identified by the radiologist. But a more radical surgical biopsy subsequently found more evidence of atypical cellular growth. Unfortunately, the margins around the sliver of biopsied flesh were too thin for a pathologist to rule out the possibility that abnormal cells had migrated into the surrounding tissue.

What to do? Dr. Willard remembers her oncologist saying, “I see women die from breast cancer every day. You have a child. Why not get a double mastectomy and a nice breast reconstruction?”

Years later, Dr. Willard remarked, “I felt genuine concern from my oncologist, which I appreciated. But it was hard to differentiate her anxiety from the actual risks and my needs.”

She eschewed the double mastectomy, but allowed her left breast to be surgically removed. A pathologist examined its cellular structures under the microscope.

Tensing, Dr. Willard whispered, “She could not find any sign of breast cancer.”


The screening paradox

In the early 1980s, tens of millions of middle-aged American women with preventative health insurance began to get breast X-rays every year or two. Nationally, the breast cancer incidence rate exploded, even as the mortality rate remained flat or decreased. The failure of the relatively static death rate to mirror the extraordinary increase in breast cancer incidence rates pointed to overdiagnosis on a mass scale.

H. Gilbert Welch of the Geisel School of Medicine at Dartmouth College is widely recognized as a leading expert in cancer overdiagnosis. He makes a twofold argument, which many other researchers have echoed, that virulent cancers are likely to kill no matter when they are detected, and that many so-called cancers detected in relatively healthy people are destined to do no harm.

“The trouble is that we doctors don’t know if an individual has been overdiagnosed unless that person forgoes treatment, lives the rest of his or her life symptom-free, and dies from some other cause,” Dr. Welch said. “Which is not to say that early detection of treatable cancers by screening does not save some lives.”

The preponderance of randomized clinical trials of screening mammography shows that for every life that may be saved by the regular screening of 1,000 healthy women, hundreds of lives are seriously compromised, some fatally. Overdiagnosed patients are harmed by treatments that include surgeries, radiation sickness, the injection of toxic chemicals that induce deleterious side effects, and secondary cancers and other diseases.

Dr. Welch and his colleagues make a convincing case that one in every four breast cancers listed in the nation’s cancer registries is an overdiagnosis.

Populations with high mammographic screening rates, such as those in Marin County or Long Island, will experience more overdiagnosis and false positives, resulting in higher incidence rates.



After her mastectomy, Dr. Willard declined the offer of a breast reconstruction.

“I felt traumatized after three surgeries in four months and did not relish the idea of a breast ‘mound’ with a tattooed nipple that would require additional surgeries along with an implant that I wasn’t sure was safe,” she said. “I wanted out of the health care system.” (Laughing, she added: “One positive thing about the ordeal is that my H.M.O. pays Nordstrom’s for three prosthetic bras a year. I never had such sexy bras before.”)

As an official cancer survivor, Dr. Willard has an elevated risk of getting more breast cancer, and she has continued to get annual mammograms.

“Organizations have vested interests, and individuals get taken under the spell,” she observed.


The official record

In 2015, curious to know if the state’s record of her ordeal is correct, Dr. Willard obtained her data abstract from the California Cancer Registry. She discovered that the abstract is missing vital information and contains substantial mistakes.

It codes her screening mammogram as “suspicious for malignancy,” for example, but it does not record her post-mastectomy pathology lab, which showed no trace of cancer in the removed breast.

Disconcertingly, the abstract encodes her D.C.I.S. diagnosis as simultaneously “infiltrating”—or invasive—and “non-infiltrating.” When asked to explain the discrepancy, Dr. Rosemary Cress, research program director for the state cancer registry, suggested that the error was made in the original pathology reports rather than in coding, which research shows results in a significant number of errors.

Regardless of where the error occurred, when the cancer registry mistakenly recorded Dr. Willard’s D.C.I.S as infiltrating, the data for Marin County included an invasive cancer case that did not exist. In turn, the county’s cancer incidence rate rose.


In next week’s installment of “Busted! Breast cancer, money and the media,” we look at a woman’s true risk of getting breast cancer—odds that are most often misconstrued in public discourse, contributing to a culture of fear and opportunities for profit.  


Peter Byrne is an investigative reporter and science writer based in Petaluma. His work has appeared in SF Weekly, Mother Jones, Scientific American, Quanta, Wired and many other publications. His internationally acclaimed book, “The Many Worlds of Hugh Everett IIII: Multiple Universes, Mutual Assured Destruction and the Meltdown of a Nuclear Family,” was published in 2010 by Oxford University Press. Learn more at www.peterbyrne.info.

Read Peter Byrne’s investigative series on a nationwide breast cancer scare that never should have happened: