THE FIRST SIGN OF TROUBLE is tiny white dots on a mammogram. The dots may be scattered like filigree along one of the ducts that connect milk-producing lobules to the nipple. They may be clustered in a single clump or spread among several of the ducts, often in a branching pattern. If these tiny dots of calcium are located inside the duct, if there is more than one locus of dots or if they create an irregular shape, they may indicate the presence of a disease known as ductal carcinoma in situ, or DCIS. In these cases, cells that might later become invasive cluster inside the milk ducts, but unless they penetrate the duct walls, they are not considered life threatening.
For this reason, doctors sometimes refer to DCIS as precancer. But because the cells are abnormal, the disease is also referred to as stage 0 breast cancer or in situ breast cancer. This lack of clarity in the nomenclature is emblematic of the disagreement among doctors and researchers about how aggressively the condition needs to be treated.
Until the widespread use of mammography, the calcium dots played essentially no role in finding potential cases of breast cancer, and diagnoses of DCIS were extremely rare. “Before 1980, fewer than 1 percent of detected breast cancers were diagnosed as DCIS. Now, because of breast-imaging devices, the figure is over 25 percent,” says Todd M. Tuttle, MD, chief of surgical oncology at the University of Minnesota in Minneapolis. That translates into more than 60,000 new cases of DCIS every year in the United States, a rate of growth that will yield a million American women living with this condition by 2020.
To many doctors and cancer researchers, the rise in the detection and subsequent treatment of these pre-malignant lesions is an important cause of the recent 30 percent drop in the death rate for breast cancer. (The other much-cited factor is improved medical therapies.) According to mainstream medical wisdom, these numbers are proof positive that finding and aggressively treating potential breast cancers early can keep abnormal cells from spreading beyond the duct into adjacent breast tissue and perhaps further into lymph nodes, lungs, bones and elsewhere.
But a small and growing coterie of specialists and researchers don’t buy the idea that medical intervention in the majority of DCIS cases necessarily improves women’s health. They say there’s no evidence that treating most instances of this precancer has been especially effective in slowing the growth rate of invasive breast cancer. “Despite all the women being diagnosed with early-stage cancer and being treated aggressively to keep their DCIS from spreading, the rate of invasive cancer hasn’t gone down; it’s gone up 25 percent,” says Laura Esserman, MD, director of the Carol Franc Buck Breast Care Center at the University of California, San Francisco, School of Medicine. The thinking of Esserman and others is that for every precancer that is found and treated early, there should be a corresponding reduction in the advanced cancer it would have become. That is exactly what happened with colon and cervical cancer: Removal of precancerous lesions has led to dramatic drops in the rates of advanced instances of the diseases. But that isn’t happening with breast cancer. “Maybe, for many cases, DCIS isn’t the right precursor for doctors to be looking for,” Esserman says.
Esserman and others believe that the high diagnosis rate of lower-risk forms of DCIS has caused an epidemic of overtreatment. Since it’s possible that some women’s DCIS cells will never spread outside the ducts, Esserman is concerned that certain low-risk patients have been needlessly subjected to surgery and radiation. Maybe there are patients who would be better off untreated. “We need to test if doctors should leave some DCIS cases alone,” Esserman says.