Usually that is what happens. But not always. Sometimes abnormal cells don’t have the courtesy to die, and they reproduce until there are thousands of sheets of cells within the duct. It’s this stage that characterizes DCIS and creates the confusion about how the same cells can be labeled “precancer” by one expert and “cancer” by another. “DCIS cells look for all the world like cancer cells,” says Hwang. One crucial difference: At this point, they’re incapable of breaking through the duct’s lining and invading the surrounding breast tissue. “Another mutation is required before they can become invasive breast cancer,” Patt says, and not all ADH cells undergo that final transformation.
In most cases, DCIS presents in two genetically distinct groups: high-grade lesions characterized by rapid growth and early progression to an invasive cancer, and low-grade lesions that more closely resemble atypical ductal hyperplasia. If these low-grade lesions, which can be difficult for a pathologist to distinguish from ADH, progress to invasive cancer, those tumors are frequently low grade, too. Doctors on both sides of the debate agree that the high-grade DCIS lesions should be treated in the conventional manner. The push for change is focused at the low-grade end of the continuum. “The majority of DCIS is in this form,” Esserman says.
THE CASE FOR THE SURVEILLANCE OPTION
Esserman is among the most outspoken of the voices for change. She and similarly minded breast-cancer specialists such as Hwang believe that it’s time to seriously look into what’s known as management by active surveillance. For DCIS, any lesion that doesn’t appear high grade would be left alone and not biopsied. Instead, if suspicious calcifications were discovered in mammography screening, patients would be given the option of forgoing treatment while doctors monitor them intensely to see what develops. This strategy is already used in treating low-risk prostate-cancer patients, who do not undergo surgery or radiation unless the lesion progresses to a higher risk level. “With early stages of prostate cancer, there is a lot of discussion about watchful waiting and active surveillance, about how cancers come in different types and how the patient has lots of options,” says Barron Lerner, MD, internist and medical historian at Columbia University Medical Center. “For DCIS, the conversation hasn’t moved so much in that direction.” And, he says, “to the degree that breast-cancer specialists consider close surveillance a reasonable option, women should be made aware of this choice.”
Active surveillance of DCIS would resemble the course of treatment offered to women who have other risk characteristics for invasive breast cancer—for example, a family history of breast cancer, atypical ductal hyperplasia or lobular carcinoma in situ (LCIS). LCIS, which develops in the lobules just up the duct from DCIS, is also called breast-cancer stage 0, but it usually doesn’t show up on mammograms and generally isn’t treated. (LCIS, recently renamed lobular neoplasia, is most often detected when breast tissue is biopsied for another reason.) According to Esserman, “Virtually all patients with DCIS undergo surgery, whereas the majority of women with a similar degree of risk due to other conditions do not choose surgical treatment. What makes invasive treatment of DCIS the accepted standard of care? With DCIS, the site of likely recurrence is known, and there is an opportunity for surgical removal.”
The naysayers who oppose the watch-and-wait strategy for DCIS don’t recommend playing the odds. They don’t want to risk seeing a low-grade case of this precancer become invasive, spreading into the breast tissue and perhaps beyond. They cite the “what if” factor: What if a doctor doesn’t do everything she can and the patient develops invasive cancer and requires even more aggressive treatments? Or dies? As any doctor will attest, it is impossible to guarantee beyond a shadow of a doubt that any individual’s cancer won’t turn out to be deadly.