Stage 0 breast cancer: Despite the zero, it sounds scary, and would have many patients anticipating surgery—even though it may not technically be cancer. Stage 0 breast cancer, also known as ductal carcinoma in situ, is defined as abnormal cells clustered inside the breast's milk ducts. It is not, at this stage, invasive, and while it could spread, it could also go away on its own. A panel of experts suggested removing “carcinoma” from its name two years ago, but for now it remains, officially, cancer. It is just one of several conditions causing researchers to realize that, in many cases, the loaded word "cancer" is applied to conditions with wildly different prognoses—often making it misleading, the New York Times reports.
The current understanding of the word dates back to a 19th-century German pathologist who examined the tissue of dead patients to identify the abnormal cells that killed them. Cancer, in each of these cases, killed. But today, doctors are examining tissue from living patients, and they can’t always predict whether the cells will cause death. And the Times notes that many doctors, unsure of the path that the "cancer" will take, treat these abnormal but sometimes harmless cells as they would harmful and invasive ones. And so a growing number of researchers are calling for some conditions, like stage 0 breast cancer and one type of prostate tumor, to be renamed. Says one professor, "The definition of cancer has changed."