An examination of breast cancer cases by The New York Times found diagnosing the earliest stage of breast cancer can be surprisingly difficult, prone to both error and case-by-case disagreement among hospitals and pathologists.
There have been numerous studies on the issue -- one study found 17 percent of ductal carcinoma in situ cases identified by needle biopsy may be misdiagnosed as cancer when no cancer exists -- and the U.S. government is currently funding a study of variations in breast pathology.
The problems in diagnosing the earliest stage of ductal carcinoma called Stage 0 or noninvasive cancer were not an issue before mammograms began to be widely used in the 1980s, because before mammograms, diagnoses were prompted by feeling a lump.
Each year some 50,000 U.S. women are diagnosed with ductal carcinoma in situ and the abnormal cells are removed before they develop into invasive cancer. However, it is estimated that if left untreated, it would turn into invasive cancer only 30 percent of the time and in some cases it would take decades to develop into cancer, The Times said.