Study Indicates That DCIS Cells May Actually Be Cancerous, Not Precancerous

A study in JAMA Oncology provides insight into the prognosis for women with stage 0 breast cancer, or ductal carcinoma in situ. It also raises new questions about the best approach to treat this condition.

The study examined outcomes for more than 108,000 women diagnosed over a 20-year period.

What Is Stage 0 Breast Cancer?

Ductal carcinoma in situ, less formally known as stage 0 breast cancer, is a diagnosis that refers to cells that are considered abnormal or precancerous and are confined to the milk ducts in the breast. Up to 60,000 women in the United States receive this diagnosis each year, according to the New York Times. As mammography technology has advanced, allowing radiologists to detect increasingly smaller areas of abnormal cells, there has been a significant increase in the number of women with this diagnosis.

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What Is the Treatment for Stage 0 Breast Cancer?

The most common treatment for ductal carcinoma in situ is surgery. A patient can get either a lumpectomy, which removes abnormal cells without removing the breast, or a mastectomy, which removes the entire breast. Some women have double mastectomies as a preventive measure even when only one breast has abnormal cells. Treatment may include radiation in addition to surgery.

What Did the Study Show?

Based on their case review of 108,000 women with ductal carcinoma in situ, the researchers estimated that after 20 years, women with this diagnosis have a 3 percent risk of dying from breast cancer, a rate that is low but 1.8 times higher than the rate for women who have not had breast cancer. The mortality rate was higher for African American women and for women who received their diagnosis before age 35, reports Medical Xpress.

The results of the study also indicate that while surgery and radiation treatments do prevent future occurrences of cancer in the breast, they actually do not decrease the likelihood that a woman with ductal carcinoma in situ will ultimately die of breast cancer. In other words, even if the cancer does not recur in the breast, it may recur as terminal metastatic breast cancer in the bones, liver or other areas of the body.

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What Does This Mean?

The exact implications of these discoveries remain unclear. According to Time, it could indicate that ductal carcinoma in situ cells are actually cancerous, rather than merely abnormal or precancerous. Dr. Steven Narod, one of the authors of the study, said, “The women who die of DCIS died because their breast cancer already spread by the time they received treatment.”

The New York Times notes that while there has been a significant increase in detection of ductal carcinoma in situ, which is considered a precursor to cancer, there has not been a corresponding reduction in cases of invasive breast cancer. Narod recommends removing suspect cells for biopsy without surgery or other treatments for ductal carcinoma in situ. This approach also avoids the risks inherent in invasive treatments, such as surgery, as well as the anxiety and distress that women often experience after mastectomies.

Breast cancer surgeon Dr. Monica Morrow feels differently, however. Since only a small number of women in the study died of breast cancer, she suggests initial misdiagnosis of these women as a possible factor in mortality.

Other possibilities are that ductal carcinoma in situ is a risk factor for cancer, rather than a precancerous condition, or that certain types of ductal carcinoma in situ are more likely to become invasive cancer. Further investigation of these possibilities could result in more effective and customized treatments.

This research raises questions about the nature of stage 0 breast cancer and how best to treat this condition, and much research still remains to be done.

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