Early cancer detection methods caused overdiagnosis

Cancer overdiagnosis may lead to unnecessary treatment and other harms, so researchers are calling for strategies aimed at quantification, recognition and management of the problem.

H. Gilbert Welch, MD, of the Veterans Affairs Outcomes Group, and William C. Black, MD,of Dartmouth-Hitchcock Medical Center in Vermont, pooled data from randomized screening trials, observational studies and population-based cancer statistics to assess the extent of cancer overdiagnosis.

They found that about 24% of breast cancers detected by mammography, 51% of lung cancers detected by chest X-ray or sputum, and 67% of prostate cancers detected by PSA were overdiagnosed.

Further data suggested a cancer overdiagnosis with CT-detected lung cancer, neuroblastoma, thyroid cancer, melanoma and kidney cancer.

“Overdiagnosis … is arguably the most important harm associated with early cancer detection,” the researchers wrote. “The impact of false-positive test results is largely transitory, but the impact of overdiagnosis can be life-long and affects patients’ sense of well-being, their ability to get health insurance, their physical health and even their life expectancy.”

Laura Esserman, MD,of the Carol Franc Buck Breast Cancer Center at the University of California San Francisco, and Ian Thompson, MD, of the department of urology at the University of Texas Health Science Center at San Antonio, wrote in an accompanying editorial, “Perhaps most importantly, we have an obligation to educate patients and clinicians to explain more and do less when appropriate. We need to make sure that patients understand that not all cancers have the potential to kill and use language that engenders less fear, for example, [indolent lesions of epithelial origin] tumors.”

Welch HG. J Natl Cancer Inst. 2010;102:doi:10.1093/jnci/djp099.