Benefits and Harms of Mammography Screening

No, next question. Ok, ok, this is a personal choice issue and everyone should be allowed to make that choice themselves, but insurers should have to offer policies with and without these dangerous "preventative" procedures.

More after the break!

Colorectal Cancer Screening: Not All It's Cracked Up to Be?

Over time we are finding preventative medicine particularly screenings have some benefits, but the physicians are deeply wedded to the idea due to the  benefit to their bottom line.

"'Unambiguous good news" — that's what the trends are in colorectal cancer incidence and mortality for adults 50 years and older in the United States, according to a pair of experts.

Since 1975, incidence has dropped by about 40% and mortality by about 50%, observe Gilbert Welch, MD, MPH, and Douglas Robertson, MD, MPH, from the Dartmouth Institute for Health Policy and Clinical Practice in Lebanon, New Hampshire.

"These trends are often attributed to screening," the pair write in an essay published in the April 28 issue of the New England Journal of Medicine.

But Drs Welch and Robertson are skeptical that screening has been that powerful.

The "magnitude of the changes alone" suggest that "other factors must be involved," they argue.

They also point out that screening is not always needed for a gastrointestinal cancer to decline dramatically in the United States. "Since 1930, without any screening effort, gastric cancer incidence and mortality have decreased by almost 90%," they report."

This makes sense, medicine has improved over time, we are more in tune with what is happening in our bodies, and when we think something amiss we are willing to see a physician.

"If gastroenterologists and other screening clinicians are taking too much "credit" for these disease trends, this could "exaggerate" the benefits of screening, Drs Welch and Robertson write.

This, in turn, could "distract from the more important activities of promoting health — for example, by encouraging a healthful diet and exercise — and caring the sick," they say.

Furthermore, although the "majority" of people who undergo colonoscopy screening have no cancer or large precancerous polyps, "they often endure repeated colonoscopy for surveillance of small polyps," the essayists explain."

The great problem in medicine today is the Cargo Cult belief that preventative medicine is an unalloyed good. While it can have benefits, it also has negatives, including the occasional death. Failing to understand the cost/benefit relationship, and falling into the fear trap is not a good. We need to take more care to understand exactly what we are doing, what the consequences are for the action, and what the potential positive outcomes are. Failing to do this leaves us open to financial, and physical peril.

"So what explains the decrease in mortality?

Three things, they say.

First, treatments have gotten better over time. Second, there is earlier detection of symptomatic cancer (which can reduce mortality even in the absence of screening) because of better awareness and better diagnostics in the clinic. Third, "there could be fewer cases of colorectal cancer in the first place," say Drs Welch and Robertson.

Dr Weber agrees with the pair that two of these phenomena have been at play, but disagrees with the third idea, as noted above.

What explains the decrease in incidence?

Again, the essayists cite three things.

An "obvious candidate" is diet, especially the reduction in the consumption of smoked and cured meats in the United States. A second factor is the increased use of antibiotics, which have reduced the prevalence of deleterious bacterial flora, such as Helicobacter pylori. Third is the increased use of nonsteroidal anti-inflammatory drugs, including aspirin.

Drs Welch and Robertson do not argue that screening has been ineffectual. They know it works to some extent. However, they want "clinicians to have some humility regarding the effect of screening on disease trends.'"

While we like to believe we are living in the period of modern medicine, this is only partially true. Be cautious of the preventative care, and screenings, and understand the downsides. 

Further reading.

Overdiagnosed: Making People Sick in the Pursuit of Health 1st Edition by H. Gilbert Welch

H. Gilbert Welch

Cancer Rates Spiked After Fukushima. But Don’t Blame Radiation

"Turtles are part of what H. Gilbert Welch, a professor of medicine at the Dartmouth Institute for Health Policy and Clinical Practice, calls the barnyard pen of cancers. The barnyard has three animals, turtles, birds, and rabbits. "The goal of early detection is to fence them in," he says.
You can't fence in the birds. They're the super aggressive lethal cancers that are beyond cure. The rabbits, you can maybe do something about if you can spot them and treat them. (Treatments that, by the way says Welch, have gotten better and better.) "But for the turtles," he says, "you don't need fences because they're not going anywhere anyway. And the thyroid is full of turtles."

The breast and the prostate are full of turtles too, and just as the thyroid-scanning ultrasound devices are more likely to find little nodules there, an upsurge in mammography has led to a corresponding upsurge in something called ductal carcinoma in situ. Basically cancers that most of the time would just sit around and do nothing if you left well enough alone. In other words, they're indolent (great word), not malignant. Whether or not we treat them (or even look for them) has been a matter of great debate in recent years.

It's very hard to know when upticks and outbreaks are quite what they appear. Even infectious disease outbreaks can sometimes be attributed to more-sensitive screening methods. The rise in whooping cough cases has multiple causes of course, but one of them is improved screening methods. Gene-based tests called PCR assays can inflate the number of actual diagnoses, according to a piece by epidemiologist James Cherry in the New England Journal of Medicine.

Which is to say, if you start looking for something carefully, and if you use better methods to see what you're looking for, you will often find it.
Welch points to an example from the '70s, when some employees at Lawrence Livermore National Labs (who deal with nuclear stuff all day long) were diagnosed with melanoma. Cancer cluster! But no--it was something else.

What happened, Welch writes in his book Should I Be Tested for Cancer, is that one person probably got sick. Then, other people in the lab started getting checked for moles. Some were funky, so that leads to biopsies, which leads to, in some cases, an actual diagnosis. Then people start really getting worried. The lab kicks off an awareness campaign, so more people go in for checks, leading to more biopsies. "The whole epidemic looked subsequently like it was a pseudoepidemic," he says. "It was an epidemic of diagnosis." The melanomas were mostly turtles.

In South Korea, checking more thoroughly has absolutely led to more diagnoses of thyroid cancer. In the late '90s, doctors in South Korea started screening people for thyroid cancer (it was an add-on test to the national cancer screening program), and cancer cases took off. "There was a 15-fold increase," says Welch. "There was nothing like it in the world!" Now, he says, thyroid cancer is the most common cancer in Korea--more common than breast, and colon, and lung.

Here's the really pernicious part. People get checked for thyroid cancer, doctor finds a little nodule, does a biopsy, there's some cancery stuff in there, so they remove the thyroid, and the person--saints be praised!--the person lives. (Because of course they lived, they just had a little thing that would never have been a problem in the first place.) They live (without their thyroid) and now they are a survivor and the survival rates for thyroid cancer in South Korea are now really high. Great, right? No. "Once you understand the problem of turtles, you understand you're giving credit to finding the cancers that don't matter," says Welch.

How did South Korea combat this surge in cancer cases? A group of doctors (including Welch) wrote a letter in 2014 discouraging screening with ultrasonography. Poof. Thyroid operations dropped by 35 percent in a year. Because the best test "isn't one that finds the most cancer," he says. 'The best test is one that finds the cancers that matter.'"

Mostly no. We diagnose lots of the turtles, especially in the breast, and prostate, and then spend millions curing these cancers which need no cure.
Then we fete our doctors for finding, and treating something which did not need to be treated. Wonderful!

"The team looked at two large, age-matched groups of women in Sweden. Starting in the late 1980s, one cohort of about 300,000 received annual mammograms for six years. A control group underwent no screening for the first four years, then had mammograms in the last two.
Conventional thinking would suggest that the cumulative number of cancers found in both groups would be about the same at the end of the six years. Surprisingly, however, the outcome was quite different: The cohort of women who were screened annually — and likely treated when a tumor was found — had accumulated significantly more tumours — 174 more per 100,000."

So, preventative testing causes tumors, ok, not really, it just finds self remitting tumors, which cause fear, and medical interventions like biopsy's, mastectomies, and other invasive surgeries, and many of these invasive surgeries will occur on women who's legion would have spontaneously remitted. Brilliant! Butchered by the Witch Doctor to quell fear, is not a medically approved procedure. 

We are too aggressive, and too fearful of these outcomes. We need to better understand what we are facing, and whether it is a "bird" cancer, super aggressive and untreatable, or a turtle, super slow no treatment necessary, or a rabbit, treatable by fencing it in. Until we do this, our treatments are little more than Witch Doctory, more damaging and deadly than valuable. And we should never fete the doctors who offer these procedures. Just as we no longer fete the Witch Doctor for offering a talisman to ward off breast cancer. 
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And prostate cancer is even worse. 

Yet our fears of cancer are too high to ignore, so we fall into the fear, and seek even the most invasive treatments without thought. There is malpractice in here somewhere.

Hat tip: BrothersJudd Blog