The Upside to Fewer Cancer Screenings in 2020
Screenings save lives, but can do serious harm too
The coronavirus pandemic will surely prompt more death from causes beyond just Covid-19. There will also be a notable number of deaths from cancer since delayed screenings and diagnoses will mean worse outcomes for many. The Director of the National Cancer Institute predicts as many as 10,000 additional deaths from colon cancer (4,700) and breast cancer (5,300) over the next 10 years as a result of just a six-month delay in screenings.
But there is a critical element missing from such alarming statistics.
Counterintuitively, the delay in screening will also probably reduce some sickness and death, and save the health care system billions of dollars. Modern screening technologies are now finding many cancers that will almost certainly never cause the patient any harm — types of breast, prostate, thyroid, and even lung cancer that have the cellular characteristics of cancer, but will never kill. This phenomenon is known as overdiagnosis. When a doctor tells a patient they have cancer, people hear the frightening “C-word” and many opt for surgery or another invasive treatment to remove an understandably frightening, but essentially nonthreatening, disease. And those treatments can cause real harm, including death.
The data for the leading cancer screening, mammography, puts this in focus. First, the good news: Mammography saves lives, at a rate of roughly three per 1,000 women screened. In 2018, the CDC reported that 39.2 million women had mammograms. That translates into 1,176 lives saved. So if there is essentially zero screening for six months in 2020 (the estimate the National Cancer Institute used), an estimated 588 lives will likely ultimately be lost because threatening breast cancers weren’t found, or were found too late to be treatable. There’s no doubt this is concerning.
Now the bad news about mammography: The screening also causes harm in a number of ways. The U.S. Breast Cancer Consortium calculates that one woman in eight gets a false positive. These worrisome findings that something might be wrong (which ultimately proves to be untrue) require women to come back for additional screening. At that rate, given 39.2 million mammograms, this form of breast cancer screening produces 4.9 million false positives per year.
Modern screening technologies are now finding many cancers that will almost certainly never cause the patient any harm.
Many studies have found that false positives do serious psychological damage. In one that compared 399 Swedish women who got false-positive mammogram results with 499 who got negative (all-clear) findings, at one month, six months, and one year after their final result, the authors noted, “The odds for experiencing short- and long-term psychosocial consequences regarding sense of dejection, anxiety, impact on behavior, sleep, and existential values were at least twice as high for the recalled women compared with controls at all study assessments.”
But false positives are only the beginning of the potential harm caused by too much screening. As screening technologies have become ever more perceptive, they have become better at finding tiny growths and “microcalcifications,” many of which turn out to be a type of breast cancer known as ductal carcinoma in situ or DCIS. 20% of all breast cancers found by mammography are DCIS. The critical part in that acronym is the IS, in situ, which indicates the cancer is in just one spot and hasn’t spread (spread is the real sign of danger). Some DCIS might spread, but an estimated 75% won’t (it is referred to as “low grade”), and the pathological examination of biopsied tissue that identifies cancerous cells can identify with reasonable confidence (but not certainty) which is which.
The problem is a lack of absolute certainty. Most women who are told they have a low-grade, nonthreatening type of DCIS understandably choose surgery anyway, to eliminate even the tiniest chance that their cancer might become a killer. Here is the data on that. An estimated 60,000 women in the U.S. were diagnosed with DCIS in 2018. 58,200 had some kind of surgery, either full mastectomies or breast conservation therapy (BCT), also known as lumpectomies. Roughly 75% of these DCIS cancers were overdiagnosed. So, roughly 44,000 women had surgery for a frightening but nonthreatening disease discovered by a mammogram.
An estimated 13,000 of these surgeries were either single or double mastectomies. The death rate after such surgery is one-quarter of 1%. That means about 30 women died as a result of first having a mammogram that then led to a clinically unnecessary surgery for a disease that (understandably) scared them.
As many as 8% of women who undergo mastectomy or BCT experience immediate or delayed serious infections, sometimes requiring hospitalization. At that rate, based on 44,000 total surgeries, 3,520 women per year suffer those impacts after a mammogram finds low-grade DCIS. Also worthy of consideration are the side effects from radiation or chemotherapy treatment that sometimes follow breast cancer surgery, and the psychosocial effects some women experience from the change in body image.
Another harm is postmastectomy pain syndrome (PMPS), the often long-lasting and sometimes disabling pain in the arm and/or chest that women experience following mastectomy or lumpectomy. Some degree of PMPS occurs in roughly one case in five, so mammograms that find low-grade DCIS that lead to surgery leave nearly 8,800 women suffering such pain, which can last for years.
And then, of course, there is the cost.
The U.S. Preventive Services Task Force (USPSTF) reviews all the evidence on cancer screening to determine which technologies will do which people the most good. Based on its research review, the task force’s current recommendation to the public is that mammography is of benefit to women between the ages of 50 and 74, if screened every other year. The USPST (and similar advisory groups in Canada, France, Switzerland, England, and elsewhere) agree that on a population basis, screening for other asymptomatic women with no other risk factors has no net benefit compared to the harms it can cause.
The problem of overscreening and overdiagnosis is still not widely recognized, and the belief in the value of cancer screening is deep.
Yet according to Ingrid Hall, epidemiologist at the Centers for Disease Control and Prevention, 20.7 million women per year in the U.S. who are younger or older than the recommended ages for screening screen anyway, leading to nearly 2 million additional follow-up mammograms and nearly half a million biopsies.
Calculations I performed for a book I’m writing estimate that this “overscreening” portion of mammography, which is not the population in which most lives are saved, costs the U.S. health care system $6.1 billion a year. (The calculations multiply the listed Medicare costs of the various types of screening and biopsies by the number of women outside the recommendations who screen, and add a factor from the Kaiser Family Foundation of roughly 85% for the higher prices paid by private insurance for a portion of the tests.) Add in the cost of the surgeries and postsurgical side effects from treating low-grade DCIS, all of which is triggered by mammography, and the total cost of the overscreening and treatment of overdiagnosed breast cancer is a staggering $8.8 billion dollars for the U.S. health care system: $1.9 billion for Medicare and $6.9 billion for private insurance.
The problem of overscreening and overdiagnosis is still not widely recognized, and the belief in the value of cancer screening is deep. In a study titled “A Bias for Action in Cancer Screening,” participants were told about a cancer screening test (mammography for women, PSA testing for men) and were then warned that “years of research have unquestionably shown that the test does not extend life or reduce the chance of death from [breast/prostate] cancer” and that the test could “lead to unnecessary treatment.” 51% of those participants wanted the screening anyway.
It is understandable that dire alarms are going off in the cancer care community about lives that may be lost because of the Covid-related decline in screening for breast, prostate, colon, and lung cancer. But the data make clear that for some of these cancers, screening is a double-edged sword. This temporary screening decline (which is already starting to normalize) provides an opportunity for researchers to measure not only the benefits of screenings, but also the costs.
