Screening for Cancer
When it comes to health care, Americans have certain beliefs deeply ingrained in our national psyche. Here are a few of our dogmas:
- Cancer is cancer, so whenever you find it, you’ve got to eradicate it completely and aggressively.
- If all cancers could be detected early, our life expectancies would increase.
- If we could all afford extensive screenings, we’d be a healthier nation.
- You should always try to fix small problems before they become big ones.
Ninety-nine percent of Americans would probably agree with those assertions. The big picture for mass screening of well people is much cloudier and more nuanced. By mass screenings we mean testing of asymptomatic people for diseases, supported by highly publicized recommendations from our government and professional associations.
The US is the only developed nation where public health officials recommend mass screenings for all symptomless and average-risk men and women aged 50-75.
One independent voice in the area of public health screening is the US Preventive Services Task Force (USPSTF). This independent panel of expert volunteers reports to Congress yearly and rates screenings on an A through D scale. Over 100 types of screenings are rated, from the A-rated ones such as the glaucoma puff test and Pap smear, to D-rated ones such as carotid artery imaging. Their website is a useful reference for understanding the many tests not covered in this chapter.
As it turns out, some of the most publicized, promoted, and expen- sive tests are also some of the most dubious in terms of their risk/benefit ratio. Are you willing to take a look at this aspect of health care and its potential effect on your future health?
To state the premise, cancer screening is another important way you can be harmed by American medicine today.
Could this really be true? The answer of public health researchers like Dr. Gilbert Welch is a resounding “yes.” In fact, many experts in public health are concerned about this, but their voices are largely ignored, opposed by the majority. As litigation is always a consideration, doctors find themselves increasingly pressured to adhere strictly to screening guidelines, and in doing so they often substitute “one size fits all” protocols for clinical judgement.
Let me oversimplify to get us started down this road. Cancers are not found very often in mass screenings. That’s a fact, says Dr. Gil Welch. Overwhelmingly, the ones that are found are small clumps of abnormal cells with low potentials to progress and metastasize. Conversely, many of the fastest growing, most lethal cancers are less likely to be found in screenings, as they are often invisible in their earliest stages but grow fast in the interval between screenings while producing symptoms. Problem number two: when found in screenings, most small cancers are still treated aggressively, opening the door for a wide array of possible serious complications.
In other words, our popular understanding of cancer, fueled by the popular media, is overly simplistic. Many groups of abnormal cells aren’t going anywhere and can be left alone. Is this the view of a few kooks on the internet? No, this is established medicine that all physicians know well but seldom communicate.The second reason screening can be harmful is that initial screenings sometimes produce inconclusive results, which may lead to even more invasive tests to establish certainty. A colonoscopy is perhaps the most dramatic example of this. We will explore this notion below.
The US is the only developed nation where public health officials (the CDC) recommend mass screenings with colonoscopies for all symptomless and average-risk men and women aged fifty to seventy- five.
Canada, alternatively, recommends fecal occult blood and DNA testing (such as Cologuard and others) beginning at age fifty and one less invasive sigmoidoscopy, a twelve-inch endoscope, done around age sixty. Canada’s death rate from colon cancer is not significantly different from that of the US. And while practitioners of colonoscopies in this country have become very skilled and their procedures have a very low major complication rate, the sheer number of colonoscopies performed, 19 million procedures per year, guarantees that there will be incidences of serious problems like perforations. These can lead to life-altering bowel resection surgeries, which have a significant mortality rate.
The shocking part is that in this multibillion-dollar industry, the number of lives saved is modest at best. Listen to one doctor, Robert Clare, MD, who is admittedly an outspoken critic of the current system:The disease I’m talking about is colon cancer and the screening test is colonoscopy. And here’s how the math works out: screen 100,000 asymptomatic people to find between 40 and 45 cancers, most of which will be early stage with a decent chance for cure. That’s the good news. Now here’s the bad news; to save those 30 to 35 people (not every person diagnosed will survive) the test will harm upwards to 250 people, meaning that for every 1 patient who benefits, between 7 and 8 will be harmed. What kind of harm am I talking about? Diarrhea and dehydration from the bowel prep before; colon perfo- ration, anesthesia reactions, and the occasional heart attack during; and GI bleeding and pain afterward. Of the people suffering these complications, a few will have heart attacks and die, a couple will suffer fatal anesthesia reactions, some will develop congestive heart failure, a couple will die from hemorrhage, and a few more from peritonitis complicating a perforated colon. In fact, you are more likely to have your colon perforated from the test than you are to have a cancer diagnosis by it. All told, you can expect 30 deaths per 100,000 colonoscopies performed, meaning that the death rate from colonoscopy is roughly equal to the number of cancer deaths averted through early detection. This is the little secret that the American Cancer Society never tells you when it advises that everybody undergo a screening colonoscopy starting at age 50.
Mass Screening for Breast Cancer
There is constant debate over the optimal frequency of screening for breast cancer in the United States. At the time of writing this, the CDC website page for “Breast Cancer Screening Recommendations” links to a table with seven different recommendations from seven different organizations. The world of mammography is in turmoil. After eight major studies in the last forty years involving half a million women, there is still no agreement on risk versus benefit.
What is clear is that there are many false positives—which cause unnecessary biopsies and emotional suffering. False positive results are quite common in the United States, says one article, with almost half of women receiving at least one positive result over ten years of annual screening.7 Additionally, some of the small masses discovered would never progress if left untreated, but they are often treated nonetheless. The more screenings that are performed, the more women are led to undergo unnecessary surgery, chemotherapy, and radiation.
Gil Welch’s take on it is this: by far the most important risk factor for breast cancer is a woman’s age. Thus, the best way to consider the benefit of mammography is a function of age, as shown below.
Mass Screening for Breast Cancer
| Age | Benefit (avoid a breast cancer death) | Do Not Benefit |
|---|---|---|
| 40 | 0.5 | 999.5 |
| 45 | 0.7 | 999.3 |
| 50 | 1.0 | 999.0 |
| 55 | 1.4 | 998.6 |
| 60 | 1.7 | 998.3 |
| 65 | 2.0 | 998.0 |
| 70 | 2.3 | 997.7 |
Mass Screenings for Prostate Cancer
Are prostate biopsies capable of spreading cancer that would otherwise remain encapsulated? Gynecologists are reluctant to sample uterine masses because they fear spread. But urologists say there is “no evidence” that prostate biopsies spread malignancy. That’s despite the fact that prostate biopsies drill an average of twelve holes in every corner of the prostate, releasing many cells into the bloodstream. There’s no evidence because there have been no valid studies. Additionally, there is a small but significant risk of infection, including life-threatening sepsis after any prostate biopsy.
So if you’re a male who still has a prostate (smile), proceed with caution.
The Facts
- Americans assume mass health screenings do far more good than harm. The real picture is much more complex, as our chapter demonstrates.
- Although both incidences are very small, you are just as likely to have your colon perforated in a colonoscopy as you are to have a cancer discovered.
- It appears far more women have unnecessary treatment as a result of mammography than are saved by early detection of a lethal cancer.
- The PSA test was not developed to be used as a mass screening tool, and using it as such leads to unnecessary surgeries and debilitating side effects.
The Path of Wisdom
- Consider following Canadian guidelines to protect yourself against colon cancer if you are a person of average risk. (Use one of the new noninvasive tests yearly after fifty, have one sigmoidoscopy at sixty.)
- Remember that breast cancer screening guidelines vary greatly across different organizations and change frequently, as experts cannot agree on the risks and benefits of mammography. Consider personal risk factors (such as family history, smoking, and obesity) when deciding when and if to participate in breast cancer screening.
- If you’re a man of average risk, check your PSA after forty-five, but consider having a biopsy only if your PSA reading is found to be shooting up, and not if it is creeping up or crosses the (moving target) guidelines now in effect. Always ask for a repeat PSA test before making any big decisions.
- Consider avoiding any traditional surgical procedures for benign prostatic enlargement.