Potential Complications of Lung Cancer Screening: Overdiagnosis
What is cancer overdiagnosis?
William Black defines an overdiagnosed cancer as one which “will never cause symptoms or kill”.
This idea is hard for most people to grasp. Popular understanding is that lung cancer is a relentless disease that will rapidly kill unless it is treated.
If doctors treat a patient with a cancer that will never cause symptoms or kill, with surgery, radiation therapy or chemotherapy, the patient derives no benefit, only harm. Such treatment is called overtreatment.
How many patients experience harm from overtreatment of overdiagnosed lung cancers?
Patients participating in screening in certified lung cancer screening programs have a very low risk of overdiagnosis and/or overtreatment.
Although critics of lung cancer screening warned early that the risk of overdiagnosis was as high as 80%, and later estimated that the early results of the NLST study showed an excess of (overdiagnosed) lung cancers in the CT-screened arm of 26%. After 11 years of follow-up in NLST, however, this excess fell to 1%.
The bottom line is that overdiagnosed lung cancer is very uncommon in lung cancer screening.
More important, the diagnostic plans (IELCAP, NCCN, LungRADS) used in lung cancer screening prevent overtreatment of overdiagnosed lung cancer.
We know now that an unknown percentage of patients with non-solid lung nodules may never develop symptoms or die of lung cancer. Non-solid nodules make up about 5% of nodules on the first CT scan; very few are seen on later annual repeat CT scans.
Biopsy or surgical removal of non-solid nodules is prevented by adherence to the diagnostic plan. No intervention is recommended – no PET scan, no needle biopsy, no bronchoscopy, no surgical resection – only another CT scan in one year is advised.
If you are interested in the sordid history of overdiagnosis and the tobacco industry, continue reading below. Otherwise, move on to the next segment.
Complications of lung cancer screening: Unnecessary operations, complications, deaths
Where did the concept of overdiagnosed cancer arise?
Pathologists performing autopsies have found cancer of the lung, thyroid and breast after patients died of other causes. These findings aroused no particular interest, until cervical cancer screening by PAP smear and mammographic screening became common medical practice in the 1940s and 1950s. PAP smears and mammograms began to detect small, pre-invasive carcinomas “in situ” (CIS and DCIS). Doctors assumed that these in-situ cancers would become invasive and kill the patient. They recommended that in-situ, non-invasive cancers should be surgically removed. Although this practice has resulted in major reduction in the number of women dying from cervical and breast cancers, some doctors began to criticize this practice. They argued that we did not know for sure that these in-situ cancers would invade and kill, many of them might be overdiagnosed. If that were true, many women might be having unnecessary hysterectomy or partial or total mastectomy.
Some extreme examples of this movement include Fiona Godlee MD, the editor of the British Medical Journal, who tells audiences that she will not have mammographic screening and Peter Goetsche who advises his daughters not to get mammograms.
In any event, no one in medicine ever believed that there was such an entity as overdiagnosed lung cancer during my medical school and residency training or the early years of my thoracic surgical training up to 1986.
In that year however, a group of doctors at Yale University headed by Alvan Feinstein MD PhD, the “father of American epidemiology and one of the “three pillars of evidence based medicine (EBM) wrote a series of articles describing lung cancers on autopsy that had not been diagnosed previously. They called these “post-mortem surprise” lung cancers. They did not use the word overdiagnosed, but when the Mayo Lung Project results were published in the late 1980s, the Feinstein publications were cited as evidence that many of the lung cancers found by chest roentgenograms (chest x-rays) were probably overdiagnosed. In the interval between then and now, the large majority, including many prominent individuals, have unflinchingly accepted this seemingly outlandish idea as true. Yet only a few individuals, including the author, challenged this idea as unwarranted.
It is worthwhile to stop and consider how this idea might be proved or disproven. Most of the proponents are also strong believers in the primacy of evidence based medicine (EBM) and, accordingly, only prospective randomized control studies could provide the needed proof. Would a reasonable adult agree to sign up for a research study that would leave their CT diagnosed lung cancer untreated, to see if it would kill them? Of course not. That would be insane as well as highly unethical. Remember that that is precisely what was done in the notorious experiment in Tuskegee, Alabama that allowed black patients with syphillis to go untreated for many years.
We now know, however, from long experience in the U.S. and Japan, that it is safe to not remove and to closely follow individuals with in-situ, non-invasive lung cancers, at yearly intervals, with CT scans. Although some patients do develop invasive cancers – as evidenced by development of solid components in non-solid nodules, most such patients are cured by surgical resection. With longer follow-up we will learn whether any and if, how many of these in-situ cancers are truly overdiagnosed. It is likely that the percentage of overdiagnosis will be lower in younger I n comparison to older patients.
Is lung cancer overdiagnosis a manufactured product of the tobacco industry?
Only after tobacco industry internal documents were leaked to University of California, San Francisco researcher Stanton Glantz and published on a University website, was it possible to learn what had gone on behind the scenes at Yale. Documents show that Alvan Feinstein began received grants as well as money from the notorious Council for Tobacco Research (CTR) for consulting and public testimony for the tobacco industry for more than thirty years between the 1960s and his death in 1997. The documented total was more than two million dollars and specifically paid for the “post-mortem surprise” research and publications. Why would the tobacco industry be interested in lung cancer overdiagnosis?
That answer became clear in the early 2000s as lawyers sought, in medical monitoring lawsuits, to compel the tobacco companies to pay for lung cancer screening that might save the lives of customers who would develop lung cancer caused by their products. Testimony from prominent medical experts in these trials cited the Yale articles as evidence that people screened for lung cancer would be harmed when overdiagnosed lung cancers were treated with surgery. A number of these expert witnesses, who had previously published articles critical of screening, had received tobacco company money and failed to disclose this information in conflict of interest reports to journal editors and readers.
These include Denise Aberle MD of UCLS, co-principal investigator of the NLST trial, William Black MD of Dartmouth University, Philip Goodman MD of Duke University and R.J. McCunney MD of Harvard University.
The tobacco industry, with the assistance of this testimony, was successful in winning in courtrooms in Louisiana, West Virginia and Massachusetts. The author testified against Philip Morris Corp in New York, California and Massachusetts.
The industry prevailed in all three actions.
This would appear to provide strong evidence to support a hypothesis that lung cancer overdiagnosis is a manufactured product of the tobacco industry.
If this were true, it would mean that not only is the tobacco industry responsible for causing the large majority of lung cancers in the twentieth and twenty-first centuries, for deliberately marketing its products to children and adolescents and for deliberately marketing its products to women = even though it was known that cigarettes cause lung cancer; in addition, they were also working behind the scenes to cast doubt upon and delay acceptance and implementation of the best opportunity to save the lives of those who made the tragic mistake of believing that it was safe to smoke their products.
Complications of lung cancer screening: Unnecessary operations, complications, deaths