Here’s some good news for a change about cancer: Cancer mortality — the rate of death from cancer — has fallen substantially over the last four decades.

There is also, however, some not-so-good news: Cancer incidence — the rate of cancer diagnoses — has been rising. This doesn’t reflect increasing dangers in our environment, but a danger in our medical system.

In this week’s New England Journal of Medicine, two colleagues and I examined the last four decades of cancer statistics in the United States. The decline in cancer mortality is a good sign. Everyone, including the National Cancer Institute, agrees that a declining cancer death rate is the best measure of progress against cancer.

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The biggest single component of this decline? Lung cancer and the recognition of a uniquely powerful causal factor: cigarette smoking.

While many studies helped produce the knowledge that smoking causes lung cancer, arguably the most persuasive one was published in 1956. It followed nearly 35,000 male physicians, the majority of whom smoked. Those who smoked more than a pack a day were 20 times more likely to have died from lung cancer than their non-smoking colleagues.

We aren’t going to find another cancer-causing factor that strong, and that common, ever again.

In 1964, the U.S. surgeon general announced that there was no doubt that cigarette smoking caused lung cancer. It took time for rates of smoking to decline, and even more time to see the effect on lung cancer death. But we are seeing it now. Big time.

The good news doesn’t stop there. There have also been real improvements in cancer treatment. For a few rare, blood-borne cancers, the improvement has been phenomenal. There has also been substantial improvement in the treatment of two more common cancers — breast and prostate cancer — reflecting the recognition that both are typically hormonally responsive diseases.

Add to that the fact that some cancers seem to be slowly disappearing, although we are not entirely sure why. Stomach, cervical, and colorectal cancers are all less commonly diagnosed now than they were in 1975 and are a less common cause of death. Fewer people are treated, fewer die: That’s really good news.

Fig1
The decline in mortality in Hodgkin’s lymphoma and chronic myeloid leukemia since 1975 reflects improvements in treatment with stable occurrence of cancer not influenced by screening. NEJM

Back to the not-so-good news. Even though overall mortality from cancer is falling, the overall incidence is rising. The declines in lung, stomach, cervical, and colorectal cancers have been more than offset by a rise in breast, prostate, thyroid, kidney, and melanoma skin cancers.

Why are more people being told they have these cancers? Blame that on overdiagnosis — the diagnosis of cancers not destined to cause symptoms or death. Overdiagnosis is not a purposeful act; it is an unfortunate side effect of our irrational exuberance for early detection.

This exuberance began with the observation that patients in whom cancer was detected early lived years longer than those in whom cancer was detected later. The simple inference was that they had benefited from early detection. Many doctors recognized the logical fallacy here, one that has nothing to do with overdiagnosis: If we start the clock earlier in the course of disease, patients will always appear to live longer — even if their time of death is unchanged.

But the horse was out of the barn. Screening efforts were initiated with the express purpose of finding small cancers that weren’t causing any symptoms. Overdiagnosis is easy to see in populations — and can be substantial — although doctors don’t know which patients are overdiagnosed.

The initiation of widespread mammography screening during the 1980s led to a 50% increase in the incidence of breast cancer. It never came back down. The advent of PSA testing a few years later doubled the incidence of prostate cancer. And changing PSA testing practices ver the years have produced a roller coaster incidence curve — the likes of which never seen before in cancer epidemiology.

Fig4
The increase in diagnoses of breast cancer and the fluctuations in prostate cancer, with minimal changes in mortality, reflect the influence of screening. NEJM

“The earlier, the better” dictum permeated medicine. Physicians felt compelled to evaluate small spots on the kidney and thyroid that they had stumbled upon while imaging for some other purpose simply because these abnormalities might be cancer. Skin moles became a source of concern and an opportunity for biopsy. The incidence of kidney cancer doubled, thyroid cancer tripled, and melanoma went up sixfold — while their death rates remained stable.

These are not epidemics of disease. They are epidemics of diagnosis.

Paradoxically, overdiagnosis helps fuel the exuberance for early detection. Survival rates skyrocket either because the clock started ticking earlier or the disease was not destined to cause death. More people appear to be cured. And more survivors — as well as more politicians — advocate for more early detection.

Overdiagnosis isn’t the only danger caused by early detection. False alarms are another: test results that initially indicate the possibility of cancer but that are ultimately shown to be wrong. The earlier doctors try to detect things, the more likely we will set off false alarms. It can take us a while to sort out these early red flags, during which more people are subjected to cascades of tests and procedures to prove they don’t have cancer.

And make no mistake: having to prove you are well can take a lot out of you physically, emotionally, and financially.

Not all the exuberance has been either irrational or unintended. Early detection is great for the business of medicine. Regular testing of broad swaths of healthy people has been a boon for the medical testing industry. It’s been equally great for hospitals and health systems, bringing them new “patients” for further investigation and treatment. Plus it serves as evidence of their paying attention to what’s known as population health — despite the lack of evidence that early cancer detection substantially improves a population’s health or longevity.

This is nothing like getting people to stop smoking. Or helping them eat real food, move regularly, and find purpose. Nor is it addressing the root causes of the rising death rates in younger white adults (hint: it’s not cancer).

If society tries to procure improved population health from the medical-industrial complex, we won’t buy more health, but simply more testing.

Early detection is always a trade-off between benefits and harms. It is influenced by a variety of factors: the biology of the disease, who is screened, how are they tested, and what happens following abnormal tests. The trade-off is most favorable in highly selected settings: individuals at genuinely high risk for cancer (think cigarette smokers) served by organized screening programs that are very attentive to minimizing overdiagnosis and false alarms.

The problem is in the leap of faith: Early detection is increasingly seen as the default solution for all cancer — and, more broadly, disease in general.

Ask your doctor what she thinks. She might point out the topic is too difficult to explain in the time allotted, and it’s much easier just to order the tests. That if she could be candid she’d say cancer screening is, at best, a reasonable choice — but never a public health imperative. And that she’d like to talk more, but she must meet her system’s performance metric for ordering mammograms.

H. Gilbert Welch, M.D., is a retired general internist, a senior researcher in the Center for Surgery and Public Health at the Brigham and Women’s Hospital in Boston, and the author of “Less Medicine, More Health — 7 Assumptions that Drive Too Much Medical Care” (Beacon Press, 2016).

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  • Kristy: Which of my “numbers are wrong”?

    The SEER database that Dr. Welch utilized, did not begin until 1974. In that year the wives of the President and Vice President of the U.S. were diagnosed with breast cancer. This triggered a short spurt of screening (which is why the data in Dr. Welch’s graph start a little high in 1975 and then drop). Biostatisticians will tell you that this then leads to a drop in numbers when screening stops (because cancers have been removed from the population). The period that Dr. Welch likes to use to claim the underlying rate of breast cancers is flat, is soon after the start of SEER. It is, actually, the least reliable. His arguments are all based on the claim that had there not been any screening, the rate of breast cancer would have been flat so that the elevated slope that you see on his graph represents fake cancers. This is false. In fact, if you look at the data from the Connecticut Tumor Registry (now part of SEER and highly respected) which provides information on the incidence of breast cancer dating back to at least 1940, before the start of SEER in 1974, the rate of invasive breast cancers was increasing steadily, by 1.0-1.3% per year (I presume these are the numbers that you think are wrong). Dr. Welch likes to ignore these actual numbers (this recent paper is his fourth). In his first paper he claimed that there would have been little rise in incidence had there been no screening, a claim that he based on is “best guess” (his words in the paper). Science should not be based on “guesses”.
    Here is one of multiple papers that provides actual numbers that you are disputing, and not “guesses”.

    Anderson WF, Jatoi I, Devesa SS. Assessing the impact of screening mammography: Breast cancer incidence and mortality rates in Connecticut (1943-2002). Breast Cancer Res Treat. 2006 Oct;99(3):333-40.

    Based on actual data, Dr. Welch’s claims are wrong. In fact, if, as the actual data suggest, the increase of 1-1.3% per year has continued, based on the increase in the baseline incidence of cancer (there is no reason to expect that it stopped after 40 years) there is no excess of invasive breast cancers. The numbers are actually a little lower than would be expected. Furthermore, with a rising incidence of all invasive breast cancers, the relative rate of advanced cancers (contrary to his claim) has dropped by approximately 40%.
    Mammography screening is not the ultimate answer to breast cancer. It does not find every cancer and does not result in a cure every time. We all want a universal “cure” for breast cancer, but none is on the horizon. While we wait for a cure, screening is available today. The overwhelming data show that tens of thousands of lives have been saved by early detection. Therapy has made remarkable advances, but oncologists who actually care for women with breast cancer (Dr. Welch does not) will tell you that we still can only cure breast cancers when we get to treat them early. Women need to be provided with facts so that they can make informed decisions as to whether or not to participate in screening.

  • Surely early detection, removal of cancer and treatment is a good thing? Or should we wait for further symptoms to appear and spread of the cancer to other parts of the body before acting?

  • Changing practices in screening must make life…interesting for the epidemiologists. The bump in prostate cancer incidence after introduction of PSA assay is obvious enough. Not so obvious is the decline in incidence before (to my knowledge) the risk of “overdiagnosis” was recognized.

    • Kristy:

      I am trying to respond to the other Kristy, but the system won’t allow me so I will respond to both Kristy’s.

      Kristy 1: For decades screening for breast cancer lost money (the reimbursement was set by Congress below actual costs), but saving lives was done as a socially conscious effort. Companies make much more money selling CT scanners and other imaging devices than selling mammography units. I would point out that the folks who want to limit breast cancer screening actually do not want to spend the money saving lives, but they won’t tell you that because they would lose the argument with you. So they have created, scientifically, unsupportable arguments to limit access. Below is my response to the other Kristy who claimed my numbers are “wrong”.

      Kristy: Which of my “numbers are wrong”?

      The SEER database that Dr. Welch utilized, did not begin until 1974. In that year the wives of the President and Vice President of the U.S. were diagnosed with breast cancer. This triggered a short spurt of screening (which is why the data in Dr. Welch’s graph start a little high in 1975 and then drop). Biostatisticians will tell you that this then leads to a drop in numbers when screening stops (because cancers have been removed from the population). The period that Dr. Welch likes to use to claim the underlying rate of breast cancers is flat, is soon after the start of SEER. It is, actually, the least reliable. His arguments are all based on the claim that had there not been any screening, the rate of breast cancer would have been flat so that the elevated slope that you see on his graph represents fake cancers. This is false. In fact, if you look at the data from the Connecticut Tumor Registry (now part of SEER and highly respected) which provides information on the incidence of breast cancer dating back to at least 1940, before the start of SEER in 1974, the rate of invasive breast cancers was increasing steadily, by 1.0-1.3% per year (I presume these are the numbers that you think are wrong). Dr. Welch likes to ignore these actual numbers (this recent paper is his fourth). In his first paper he claimed that there would have been little rise in incidence had there been no screening, a claim that he based on is “best guess” (his words in the paper). Science should not be based on “guesses”.
      Here is one of multiple papers that provides actual numbers that you are disputing, and not “guesses”.

      Anderson WF, Jatoi I, Devesa SS. Assessing the impact of screening mammography: Breast cancer incidence and mortality rates in Connecticut (1943-2002). Breast Cancer Res Treat. 2006 Oct;99(3):333-40.

      Based on actual data, Dr. Welch’s claims are wrong. In fact, if, as the actual data suggest, the increase of 1-1.3% per year has continued, based on the increase in the baseline incidence of cancer (there is no reason to expect that it stopped after 40 years) there is no excess of invasive breast cancers. The numbers are actually a little lower than would be expected. Furthermore, with a rising incidence of all invasive breast cancers, the relative rate of advanced cancers (contrary to his claim) has dropped by approximately 40%.
      Mammography screening is not the ultimate answer to breast cancer. It does not find every cancer and does not result in a cure every time. We all want a universal “cure” for breast cancer, but none is on the horizon. While we wait for a cure, screening is available today. The overwhelming data show that tens of thousands of lives have been saved by early detection. Therapy has made remarkable advances, but oncologists who actually care for women with breast cancer (Dr. Welch does not) will tell you that we still can only cure breast cancers when we get to treat them early. Women need to be provided with facts so that they can make informed decisions as to whether or not to participate in screening.

      Which of my “numbers are wrong”?

      The SEER database that Dr. Welch utilized, did not begin until 1974. In that year the wives of the President and Vice President of the U.S. were diagnosed with breast cancer. This triggered a short spurt of screening (which is why the data in Dr. Welch’s graph start a little high in 1975 and then drop). Biostatisticians will tell you that this then leads to a drop in numbers when screening stops (because cancers have been removed from the population). The period that Dr. Welch likes to use to claim the underlying rate of breast cancers is flat, is soon after the start of SEER. It is, actually, the least reliable. His arguments are all based on the claim that had there not been any screening, the rate of breast cancer would have been flat so that the elevated slope that you see on his graph represents fake cancers. This is false. In fact, if you look at the data from the Connecticut Tumor Registry (now part of SEER and highly respected) which provides information on the incidence of breast cancer dating back to at least 1940, before the start of SEER in 1974, the rate of invasive breast cancers was increasing steadily, by 1.0-1.3% per year (I presume these are the numbers that you think are wrong). Dr. Welch likes to ignore these actual numbers (this recent paper is his fourth). In his first paper he claimed that there would have been little rise in incidence had there been no screening, a claim that he based on is “best guess” (his words in the paper). Science should not be based on “guesses”.
      Here is one of multiple papers that provides actual numbers that you are disputing, and not “guesses”.

      Anderson WF, Jatoi I, Devesa SS. Assessing the impact of screening mammography: Breast cancer incidence and mortality rates in Connecticut (1943-2002). Breast Cancer Res Treat. 2006 Oct;99(3):333-40.

      Based on actual data, Dr. Welch’s claims are wrong. In fact, if, as the actual data suggest, the increase of 1-1.3% per year has continued, based on the increase in the baseline incidence of cancer (there is no reason to expect that it stopped after 40 years) there is no excess of invasive breast cancers. The numbers are actually a little lower than would be expected. Furthermore, with a rising incidence of all invasive breast cancers, the relative rate of advanced cancers (contrary to his claim) has dropped by approximately 40%.
      Mammography screening is not the ultimate answer to breast cancer. It does not find every cancer and does not result in a cure every time. We all want a universal “cure” for breast cancer, but none is on the horizon. While we wait for a cure, screening is available today. The overwhelming data show that tens of thousands of lives have been saved by early detection. Therapy has made remarkable advances, but oncologists who actually care for women with breast cancer (Dr. Welch does not) will tell you that we still can only cure breast cancers when we get to treat them early. Women need to be provided with facts so that they can make informed decisions as to whether or not to participate in screening.

  • Spend $500 a month for medical insurance. Wait three months for an appointment with primary care physician. Spend 7 to 8 minutes with physician who barely looks at you and is careful not to touch you or palpate any part of you. Be abruptly cut off by busy physician when your time is up. Spend the next three months getting labwork, colonoscopy, mammogram, EKG and treadmill, bone density scan and an MRI of this and that. Hundreds or thousands of dollars later in copays, depending on complicated factors over which you have no insight or control, you decide to just join Planet Fitness, eat more fiber, and stay away from doctors for another ten years or so.

  • Great article! To take it a step further, there are those who are mistakenly told they have cancer or may have cancer and treated as such. The gynecology specialty has a long track record of over-treating. Less than 8% of hysterectomies are done for a cancer diagnosis. Likewise, 90+% of ovary removals / oophorectomies (c*str*tions) are also unnecessary. Shockingly, ~45% of U.S. women end up having a hysterectomy. And the oophorectomy rate is 73% of the hysterectomy rate. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3804006/ This is an epidemic of intentional harm! The uterus and ovaries have lifelong functions. Numerous studies show that these surgeries do more harm than good when done for benign conditions yet they continue at alarming rates. Very few women would consent to these surgeries if they were told the truth. Just read the hysterectomy articles and comments on Hormones Matter.

  • Thank you Dr. Welch. You are a true hero. I have been researching the problem that I found myself faced with and you explain it so clearly. Gave me so much reassurance that low grade DCIS (stage zero) breast cancer is likely being over-detected through mammography then all are over-treated. The psychological trauma this does to women and their families is a travesty. I created a blog to share my story and help educate women so they do not rush to treat. But we can do even better by informing women of potential overdiagnosis and overtreatment BEFORE they get screened. Currently women feel coerced and intimidated into mammography which has a monopoly on screening. Those with vested interests such as radiologists and surgeons should not influence women’s choices. If their livelihood depends on screening then they of course have a bias towards screening. Women must be informed of the real serious harms of mammography! Thank you and may God bless you!! Donna Pinto, Founder of DCIS 411

  • Fortunately, Dr. Welch is completely wrong about breast cancer. In each of his papers, including the most recent, he has continued to ignore the facts. The incidence of breast cancer has been increasing steadily by 1-1.3% per year since at least 1940. That is why the graph appears tilted up from left to right. The bump that you can see in his graph is the expected “prevalence” bump (statistics 101) that began when women started to participate in screening in the 1980’s and, as expected, it persisted until 1999 when participation in screening plateaued. It has now returned to the increasing baseline which has been explained by environmental factors and delays in first full term pregnancies. In fact, there are actually fewer breast cancers now than expected probably due to the removal of the earliest form of breast cancer due to screening. The good news is that the death rate has, indeed, fallen coinciding with the start of screening. Therapy has improved, but therapy cannot cure advanced breast cancer. In the Harvard hospitals more than 70% of the women who died from breast cancer were among the 20% who were not participating in screening. Therapy saves lives when breast cancers are treated early. Screening is the main reason that deaths have declined. The death rate for men with breast cancer has not budged since 1990 because we are not being screened.

    • Thank you for this comment. I’m confident that I have survived breast cancer (Stage 2) to age 70 only because it was caught when I was 52. If screening had not been virtually an automatic expectation of my gynecologist, I would never have been screened, and thus (I believe) would not be alive today.

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