Cautions on cancer screening, overdiagnosis and overtreatment

Several noteworthy articles in journals today.

In JAMA, a breast cancer specialist, a prostate cancer specialist, and an esophogeal cancer specialist co-authored a Viewpoint article, “Overdiagnosis and Overtreatment in Cancer: An Opportunity for Improvement.” Excerpt:

“In March 2012, the National Cancer Institute convened a meeting to evaluate the problem of “overdiagnosis,” which occurs when tumors are detected that, if left unattended, would not become clinically apparent or cause death. Overdiagnosis, if not recognized, generally leads to overtreatment. This Viewpoint summarizes the recommendations from a working group formed to develop a strategy to improve the current approach to cancer screening and prevention.

Periodic screening programs have the potential to identify a reservoir of indolent tumors. However, cancer is still perceived as a diagnosis with lethal consequences if left untreated.

An ideal screening intervention focuses on detection of disease that will ultimately cause harm, that is more likely to be cured if detected early, and for which curative treatments are more effective in early-stage disease. Going forward, the ability to design better screening programs will depend on the ability to better characterize the biology of the disease detected and to use disease dynamics (behavior over time) and molecular diagnostics that determine whether cancer will be aggressive or indolent to avoid overtreatment. Understanding the biology of individual cancers is necessary to optimize early detection programs and tailor treatments accordingly. The following recommendations were made to the National Cancer Institute for consideration and dissemination.

Physicians, patients, and the general public must recognize that overdiagnosis is common and occurs more frequently with cancer screening. Overdiagnosis, or identification of indolent cancer, is common in breast, lung, prostate, and thyroid cancer. Whenever screening is used, the fraction of tumors in this category increases. By acknowledging this consequence of screening, approaches that mitigate the problem can be tested.

Change cancer terminology based on companion diagnostics. Use of the term “cancer” should be reserved for describing lesions with a reasonable likelihood of lethal progression if left untreated. There are 2 opportunities for change. First, premalignant conditions (eg, ductal carcinoma in situ or high-grade prostatic intraepithelial neoplasia) should not be labeled as cancers or neoplasia, nor should the word “cancer” be in the name. Second, molecular diagnostic tools that identify indolent or low-risk lesions need to be adopted and validated. Another step is to reclassify such cancers as IDLE (indolent lesions of epithelial origin) conditions.  … A multidisciplinary effort across the pathology, imaging, surgical, advocate, and medical communities could be convened by an independent group (eg, the Institute of Medicine) to revise the taxonomy of lesions now called cancer and to create reclassification criteria for IDLE conditions.

Mitigate overdiagnosis. Strategies to reduce detection of indolent disease include reducing low-yield diagnostic evaluations appropriately, reducing frequency of screening examinations, focusing screening on high-risk populations, raising thresholds for recall and biopsy, and testing the safety and efficacy of risk-based screening approaches to improve selection of patients for cancer screening. The ultimate goal is to preferentially detect consequential cancer while avoiding detection of inconsequential disease.”

And the authors conclude with a message to the media:

“The media should better understand and communicate the message so that as a community the approach to screening can be improved.”

Amen.  It’s why we devote so much time, space and energy on this site and in our frequent public presentations to the topic of media messages on screening tests.


Now let’s turn specifically to lung cancer screening. Former US Preventive Services Task Force staffer Dr. Kenny Lin writes,Should you be screened for lung cancer? Maybe not, and here’s why.” Excerpts:

“If you are a lifelong heavy smoker age 55 years or older, the U.S. Preventive Services Task Force believes that screening for lung cancer with CT scans may save your life. Today the Task Force released provisional recommendations that assigned a “B” letter grade to this preventive service, which, if eventually finalized, would place CT scans alongside established cancer screening tests such as mammograms and Pap smears and mandate that health insurers cover these scans without cost sharing for eligible patients. …

In my mind, there are at least 4 good reasons for current or former smokers to think twice about being screened for lung cancer:

1. The risk of developing cancer from the CT scan itself isn’t trivial. An analysis published in the Archives of Internal Medicine found that a typical chest CT scan exposes patients to the radiation equivalent of more than 100 chest X-rays, and that at age 60, an estimated 1 in 1000 women or 1 in 2000 men would eventually develop cancer from that single scan. Although some imaging centers now use lower radiation doses, repeating these lower-dose CT scans annually still adds up. (It hasn’t been long enough since the conclusion of the NCI’s lung cancer screening study to measure how much these scans increased the participants’ risk for other cancers.)

2. False alarms are extremely common. In the NCI’s study, more than 96 percent of all positive results turned out to be false positives, and in a previous CT screening study, 1 in 3 patients had at least one false-positive result after undergoing only two CT scans. Of those patients, 1 in 14 needed an invasive lung biopsy to be sure they were cancer-free. Such diagnostic procedures for lung cancer can themselves be life-threatening: in 2005, former Canadian prime minister Brian Mulroney (a longtime heavy smoker) spent several weeks in the intensive care unit after postoperative complications from surgery to remove two lung nodules found on a screening CT scan that turned out to be non-cancerous.

3. A CT scan for lung cancer could find some other unrelated abnormality that will require further investigation; in the NCI’s study, this occurred in about 1 in every 13 patients. You might think this is a good thing, but most of these abnormalities (known as “incidentalomas”) turn out to be false alarms, too. In fact, in 2008 this very same Task Force decided against endorsing CT screening for colorectal cancer due to concerns that invasive testing to definitively diagnose all of the abnormalities that CT scans turn up could easily outweigh the cancer-prevention benefits.

4. Finally, even if screening catches a true lung cancer early, there’s no guarantee your prognosis will be better. This is due to “overdiagnosis,” or the unnecessary diagnosis of a condition (typically cancer) that will never cause symptoms in a patient’s lifetime, either because it’s so slow-growing or the patient dies from some other cause. (Statistics show that most lifelong smokers will die from heart disease, not lung cancer.) An estimated 1 in 3 breast cancers detected by screening mammograms is overdiagnosed, and a 2007 study published in the journal Radiology suggested that the proportion of lung cancers overdiagnosed by CT scans could be as high or higher, especially in women. But because there’s no way of knowing at the time of diagnosis if a lung cancer will be fatal, inevitably most of these patients will be needlessly subjected to the side effects of treatment – making the “cure” worse than the disease.

I expect that some of my patients will decide to be screened with CT scans for the obvious upside emphasized by the U.S. Preventive Services Task Force: a small chance of preventing death from lung cancer. But before they make this decision, I will counsel them to carefully consider the more likely downsides, and only choose testing if they’re prepared for these too.”

Kenny Lin – and some of those behind the JAMA Viewpoint article (Laura Esserman, Barry Kramer, Gil Welch, Donald Berry, Bill Black, David Ransahoff, etc.) are important voices for helping to shape the future of American health care.  If we don’t improve our discussion of the screening issues, we’ll never tackle overdiagnosis, and, in turn then, we’ll never tackle overtreatment.  And so we’ll never effect truly meaningful health care reform in this country.


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Lung Cancer Alliance

July 29, 2013 at 7:12 pm

A monumental moment in the fight against lung cancer.  
Find out if you’re at risk, and if you are, get a scan