The risk of overdiagnosing breast cancer

For the past several decades, public health authorities in Canada and the U.S. have argued that screening and early detection through mammograms is essential to fighting breast cancer. Renée Pellerin's new book, Conspiracy of Hope: The Truth About Breast Cancer Screening, explores how screening became widespread in the U.S. and Canada before there was any good evidence that it made a difference. Now, there is significant evidence that screening does more harm than good because, among other reasons, it can lead to overdiagnosis. In the following excerpt from Conspiracy of Hope, Penny Gerrie shares her own story of overdiagnosis.

A few days after her seventy-sixth birthday, Penny Gerrie bought a new bicycle. Her old no-gear coaster bike had served her well for many years, but it was heavy, and she was finding it increasingly difficult to lift it up the front steps and into the foyer of the house where she rents an apartment. Use of her sister’s seven-speed for a while convinced her of the value of gears when navigating hills. So that's what she chose: a seven-speed in a low-key muted bronze, a colour she hoped would not attract the attention of thieves. Neither fancy nor fussy, the bike is a practical mode of transportation for someone who doesn't own a car.

Gerrie lives in Toronto and regularly cycles long distances from one end of the city to the other. Long before the city developed its current network of bike lanes, she decided that cycling was more convenient than public transit. She also enjoys the exercise. For the same reasons, she has always walked a lot, and a seven-kilometre route was once a three-times-a-week routine. On a nice day, she'd meet a friend for lunch downtown, an hour away on foot, and walk another hour back. She’s thin and fit, with a confident posture. Her elegant short hair, good bones, and stylish dress complete a striking picture that disguises her age by at least a decade. She could be a fashion model.

Health conscious but not obsessive about it, Gerrie is the kind of person who sees a doctor only when she needs to. In the summer of 2016, she began to experience some worrying pain in her hips and knees on her long walks. The mobility she took for granted seemed to be slipping away, and wanting to do something about it, or at least find out what was going on, she made an appointment. Her doctor decided to order x-rays. When a look at Gerrie's chart revealed that she hadn’t had any of the usual screening tests for at least five years, she also suggested a colonoscopy, a bone density test, and a mammogram. Gerrie dutifully consented. At this point, she was a healthy seventy-five-year-old seeking pain relief.

She'd soon find herself spiralling down a medical rabbit hole.

The x-rays revealed some minor arthritis in her right hip for which her doctor advised physiotherapy. It was a relief that the diagnosis wasn't serious and that preventing pain was possible. That done, she went for the other tests, all arranged in the same week in the middle of October. A few days after the mammogram, the breast-screening clinic called to request that she come in again for additional mammography of the right breast. Like many women, Gerrie had been called back for a second mammogram once before. It happens. Sometimes the images aren't quite clear enough. No big deal, she thought. But the woman on the phone insisted that she get it done at the earliest possible date. She also told her to prepare to be there a few hours, in case she needed a biopsy. Gerrie was more annoyed than worried. She'd have to miss a special movie showing she’d been looking forward to.

She returned to the clinic on October 31, just two weeks after the first mammogram. The new images confirmed a small lump, a tiny mass not big enough to feel. She was ushered to another room for a core needle biopsy. Before proceeding, the doctor studied the original mammograms of both breasts, as well as the new ones of the right, and his eye caught something suspicious, unnoticed before, in the left breast. He decided to biopsy that too. In her typically practical approach to things, Gerrie appreciated the convenience of having both biopsies done at once. The procedure was painless, with no after-effects. She went home to await the results.

Her family physician gave her the news on the phone. It shouldn’t have happened that way, but an emergency in the doctor's family meant that an office visit could not be immediately arranged. Both lumps were cancer, the doctor told her, but they were very small, and she would likely not need more than simple lumpectomies.

Gerrie's first meeting with her surgeon, on November 21, was also reassuring. She would have the lumpectomies in just two weeks. She doesn’t remember being afraid. Her elder sister had been diagnosed with breast cancer at the same age, five years earlier, and always said it was a piece of cake. Gerrie quipped in an email that she was concerned only about not being able to lift more than ten pounds for the first two weeks after the surgery. She also griped about the "stupid" questionnaires at every stop, always repeating the same questions. "I swear I gave them four different dates for the start of menstruation," she said. "I just couldn’t remember." She was grateful to the radiologist who found the lump in the second breast, thinking if he hadn’t been so thorough, she'd be going through all of this again in a few years.

On December 7, less than eight weeks from the first mammogram, she was in the operating room. The rapid pace at which one appointment led to the next and then to the next didn’t leave much time to think about anything except stocking the fridge and getting organized. Gerrie had begun physiotherapy for her hip, but she let that slide in the whirlwind the diagnosis of breast cancer created. She lives alone but is fiercely self-sufficient, and she told friends not to worry, that a close neighbour would take her home from hospital and be on call for anything she needed. Everything was under control.

She glided smoothly through recovery without much pain -- only some discomfort from bruising and swelling and irritation at having to sleep in a bra. The pathology report indicated two tiny tumours, the one in the right breast only six millimetres in diameter and the one in the left only five millimetres. No lymph nodes were involved. Gerrie had a low-grade stage one cancer, classified as ER-positive, a kind that is less aggressive than others. This was all good news, but she didn’t yet know what follow-up treatment she would need. Her file was now in the hands of an oncologist.

She waited three more weeks. The day she met the oncologist was one of those dreary, cloudy days when you don’t know whether to expect rain, snow, or both. It's weather that chills to the bone. Such an ominous, oppressive hovering in the air makes it hard to have an optimistic outlook. But Gerrie was in for a surprise. The oncologist, a specialist in chemotherapy and drug treatments, was frank in a way she didn’t expect.

Did she know about overdiagnosis? And overtreatment? He explained that overdiagnosis of breast cancer happens to a lot of older women. If she had never had a mammogram, she would likely have lived another ten or twenty years without even knowing she had tumours in her breasts. They might never have caused any problems. Go home, he prescribed, and celebrate a Happy New Year. He wasn’t going to advise any further treatment. Wow, she thought, he just told me that it was all unnecessary.

She still had to see a radiation specialist. Even though she wouldn’t need drugs or chemotherapy, she thought radiation might be recommended. That didn't happen either. The specialist told her that without treatment, the chance of the cancer recurring within ten years was about 15 percent. So how would she feel about risking another lumpectomy instead of undergoing any radiation? he asked. She was fine with that. He asked her to think about the radiation, but he was not at all insistent on it. It reaffirmed what she was already thinking, that all she had been through in the last few months was pointless.

Gerrie was aware of some of the issues around mammography screening, but she followed her family doctor’s advice because, as she says, "You just do." She wishes now that the kindly oncologist had been the first doctor she'd seen in her breast cancer journey. But overdiagnosis is complicated. It's easy to understand that mammograms sometimes give false positive results, meaning that whatever is detected on the image turns out to be innocent when biopsied. Women are also warned that mammograms can miss cancers. It's never been a perfect test.

Overdiagnosis, however, refers to the phenomenon where the cancer is real yet indolent, and the consequence is unnecessary surgery followed by unnecessary chemotherapy or radiation. The conundrum is that it's currently not possible to know which cancers will remain indolent. Once they’re detected, ignoring them is not an option. Gerrie's oncologist could not have told her for certain, and she will never know, what would have happened if no one had squeezed her breasts into a mammography machine.

Three months after the lumpectomies, Gerrie was still feeling some numbness under her right arm, and she was unhappy about being lopsided, with one breast smaller than the other. Corrective surgery was a possibility, but she didn't even want to think about another operation. The thing that bothered her most was that she had put aside the issues with her hips and knees. The pain had become much more severe in the last few months, and when she was done with breast cancer, she saw a rheumatologist and had more x-rays. This time, the diagnosis was severe arthritis in the right hip and moderate arthritis in the left.

She wonders if she would be in this "pickle," as she calls it, if the breast cancer hadn't distracted her from worrying about her joints. Adding to her frustration, arranging follow-up on the arthritis diagnosis was slow in comparison with the speed with which she was ushered through the cancer protocol. It would take nearly a year before she finally had hip surgery.

Penny Gerrie was seventy-five when her doctor sent her for a routine mammogram. Most public breast screening programs stop inviting women at age seventy, and none extend the routine screening age beyond age seventy-four. The fact that her sister had breast cancer was no doubt a consideration in the family doctor’s mind, and it was in Gerrie’s too. Family history is often assumed to be a major risk factor, although research shows that in older women, it is far less significant than either dense breasts or obesity. But Gerrie never considered the risk of overdiagnosis and potential overtreatment until she saw the oncologist.

Image: Air Force Medicine

Excerpted with permission from Chapter 8 of Conspiracy of Hope, by Renée Pellerin. Published by Goose Lane Editions, October 2018.

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