Scientists see harm in overly broad definition of cancer
A group of experts advising the nation’s premier cancer-research institution recommends changing the definition of cancer and eliminating the word entirely from some common diagnoses to reduce cases of overtreatment.
Bloomberg News and The New York Times
Low-risk growths in the breast, prostate and elsewhere should no longer be identified as cancer, and screening efforts to spot them should be reduced, a panel convened by the U.S. National Cancer Institute said in recommendations published Monday in the Journal of the American Medical Association.
The experts suggested changing the definition of cancer and eliminating the word from some diagnoses as part of changes in the nation’s approach to cancer detection and treatment.
The impetus behind the call for change is a growing concern among doctors, scientists and patient advocates that men and women are undergoing needless and sometimes disfiguring and harmful treatments for premalignant and cancerous lesions that are so slow-growing they are unlikely to ever cause harm.
A three decades-long emphasis on the early identification of tumors was based on the idea that cancerous cells always spread and eventually kill, the researchers said. Instead of sparking a drop in the number of cancer deaths nationwide, the approach has led to toxic treatment of millions of people who may have never had any symptoms from indolent lesions.
“The goal going forward is to personalize screening strategies and focus screening policies on the conditions that are most likely to result in aggressive illness and death,” said Laura Esserman, director of breast care at the University of California, San Francisco’s cancer center. “By recognizing that cancer is not one disease, but a number of different diseases, we can individualize our treatment.”
The group led by Esserman said overdiagnosis and excess treatment is common, and screening exacerbates the problem. It recommended cutting the frequency of screening and its use in people who probably won’t get the disease. The bar also should be raised for repeat tests and biopsies, it said.
“Although no physician has the intention to overtreat or overdiagnose cancer, screening and patient awareness have increased the chance of identifying a spectrum of cancers, some of which are not life threatening,” the researchers said. “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.”
They say that some premalignant conditions, like one that affects the breast called ductal carcinoma in situ (DCIS) — which many doctors agree is not cancer — should be renamed to exclude the word carcinoma. That way, patients are less frightened and less likely to seek what might be unneeded and potentially harmful treatments.
The group, which includes some of the top scientists in cancer research, also suggested that many lesions detected during breast, prostate, thyroid, lung and other cancer screenings should not be called cancer at all, but should instead be reclassified as IDLE conditions, which stands for “indolent lesions of epithelial origin.”
The report from such a prominent group of scientists with the clear backing of the National Cancer Institute brings the discussion to a much higher level and will most likely change the national conversation about cancer, its definition, treatment and future research.
The advent of highly sensitive screening technology in recent years has increased the likelihood of finding so-called incidentalomas — the name given to incidental findings detected during medical scans that most likely would never cause a problem. However, once doctors and patients are aware a lesion exists, they typically feel compelled to biopsy, treat and remove it, often at physical and psychological risk to the patient.
The issue is often referred to as overdiagnosis, and the resulting unnecessary procedures to which patients are subjected are classed as overtreatment. Officials at the National Cancer Institute say overdiagnosis is a major public-health concern and a priority of the agency.
Such proposals will not be universally embraced. Dr. Larry Norton, the medical director of the Evelyn H. Lauder Breast Center at Memorial Sloan-Kettering Cancer Center, said the larger problem is that doctors cannot tell patients with certainty which cancers will not progress and which cancers will kill them, and changing terminology does not solve that problem.
“Which cases of DCIS will turn into an aggressive cancer and which ones won’t?” he said. “I wish we knew that. We don’t have very accurate ways of looking at tissue and looking at tumors under the microscope and knowing with great certainty that it is a slow-growing cancer.”
The concern, however, is that since doctors do not yet have a clear way to tell the difference between benign or slow-growing tumors and aggressive diseases with many of these conditions, they treat everything as if it might become aggressive.
As a result, doctors are finding and treating scores of seemingly precancerous lesions and early-stage cancers — like ductal carcinoma in situ, small thyroid tumors and early prostate cancer.
But even after aggressively treating those conditions for years, there has not been a commensurate reduction in invasive cancer, suggesting that overdiagnosis and overtreatment are occurring on a large scale.