The problem with Taylor Swift's advice about cancer screening

Last Christmas, Taylor Swift asked her mom to go to the doctor and get screened for health issues, "just to ease some worries of mine," the performer wrote on her blog today.

The results were surely not what Swift was hoping for: her mother, Andrea Swift, has been diagnosed with cancer.

For now, Swift says she is keeping the details of her mom's diagnosis and treatment secret. But she is already wading into the celebrity health advocacy realm, urging her fans to have their parents get screened, too:

She wanted you to know because your parents may be too busy juggling everything they've got going on to go to the doctor, and maybe you reminding them to go get checked for cancer could possibly lead to an early diagnosis and an easier battle... Or peace of mind in knowing that they're healthy and there's nothing to worry about. She wanted you to know why she may not be at as many shows this tour. She's got an important battle to fight.

While she surely has the best intentions, Swift makes a common error of assumption here: that more is better when it comes to cancer screening.

In many cases, this isn't true.

Consider a recent study in the New England Journal of Medicine on thyroid cancer in South Korea. In 1999, the country launched an ambitious campaign to improve health by finding and treating diseases like cancer. Part of this effort included a state-subsidized mass screening program. In two decades, the number of South Koreans diagnosed with thyroid cancer rose 15-fold.

While this might sound like a great success, the country didn't actually succeed at its mission: improving health. Thyroid cancer deaths remained stubbornly stable as the incidence of the disease skyrocketed. The additional screenings were leading to discovery of many more cases, but those additional diagnoses — and the invasive courses of treatment that came along with them — weren't making thyroid cancer any less deadly.

Some cancer screenings may actually do more harm than good

(Chart courtesy of the New England Journal of Medicine)

Dr. Gilbert Welch, author of Less Medicine, More Health who worked on the South Korea study, said it's very difficult to get the message across that more isn't necessarily better when it comes to cancer screening.

Over a decade ago, the Dartmouth physician-researcher began looking into the effects of mass screening programs that have emerged around the globe. These take otherwise healthy people and subject them to tests to find out whether they have lumps and bumps that may be malignant. (Note: Mass screening is different from using technologies like ultrasounds to diagnose people at risk of a disease or who have symptoms that require investigation.)

He found something disturbing: in many cases, screening wasn't actually helping people or saving lives.
healthy people should think twice about getting screened
His study of thyroid cancer screening in South Korea adds yet more fodder for his crusade to make healthy people think twice about getting screened. If screening programs worked as intended, more diagnoses would correlate with fewer deaths. The chart below illustrates how that's not happening. As you can see, it looks as if there’s a surge in thyroid cancer in South Korea, yet the related death rate has held constant.

In the US, during the same period, diagnoses of thyroid cancer more than doubled, but we also had a death rate that remained stable.

The problem of overdiagnosis

Harding Center for Risk Literacy

(Chart via the Harding Center for Risk Literacy)

Swift wouldn't be the first celebrity to suggest people get screened for cancer. Katie Couric, Angelina Jolie, Kylie Minogue — all have pushed their fans to consider getting tested.

Their advice usually works on us. A number of studies have shown that when a celebrity advocates for a certain type of cancer screening, people start calling their doctors, and screening rates surge.

But what's often lost in their good intentions is what Welch and his colleagues refer to as "overdiagnosis": the diagnoses of cancers that would not have been fatal or even harmful. These are diagnoses that turned healthy people into cancer patients unnecessarily, leading them to unnecessary treatment and hospitalization, creating clubs of "cancer survivors" who actually would have lived even if their cancers were left in them.

"When you use a powerful technology to screen for lung cancer, it looks like smokers and non-smokers have [the same cancer rate]" To be clear: not all mass screening is bad. Colorectal cancer screening, for example, has been shown to save lives as a result of early detection, and the Pap test transformed cervical cancer into a treatable disease.

Still, Welch has found evidence of overdiagnosis in breast and kidney cancers, as well as melanoma. Population-based screening for prostate cancer has been scaled back after the realization that most men will die with, not of, the disease.

Welch even found overdiagnosis in lung cancer. "That's the wildest one," he said. "We all think of lung cancer as being the most aggressive, and of course it can be."

But overdiagnosed lung cancer has been documented since the early 1980s. "The most powerful example of population-based screening was in Japan, where they started using spiral CT scanning to do mass screening and found the same rate of cancer in smokers as nonsmokers," said Welch.  

For the past 50 years, we have known that smokers are at a 20- to 30-times-greater risk of dying from lung cancer. But "when you use a very powerful technology to screen for lung cancer, it looks like smokers and nonsmokers are about the same" for rate of lung cancer, Welch said.

How to avoid being a victim of overdiagnosis

Taylor Swift suggests people go by the "screen more, screen often" adage. Welch would take a different approach. To avoid being the victim of overdiagnosis, he suggests people talk to their doctors about their individual risks before getting screened. The US Preventive Services Task Force, which examines the evidence and makes recommendations about mass cancer-screening programs, is also an excellent resource.

Getting the message across that not all cancer is deadly, and finding it early can actually do more harm than good, hasn't been easy, he added.

"All the forces line up to support early cancer detection," he explained. "On first inspection it makes total sense, it's so intuitively appealing. And then the more people who are diagnosed with thyroid cancer, who have their thyroids taken out, and who are doing well — other than the fact that they're on medications or may have vocal cord paralysis — the more they are seen as survivors."

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