No Survival Benefit for Mastectomy Over Breast-Conserving Surgery in DCIS Patients

HAMBURG, Germany—More than 90% of woman diagnosed with ductal carcinoma in situ (DCIS) will still be alive 10 years after diagnosis and treatment, regardless of how they were initially treated. Research data confirming these findings were presented at the 4th European Breast Cancer Conference (abstract 461).

Dennis R. Holmes, MD, assistant professor of clinical surgery, University of Southern (USC) California Keck School of Medicine, said that the study results offer reassuring evidence to woman with DCIS who opt for lumpectomy. "Choosing lumpectomy over mastectomy will not make any difference to their chances of surviving the disease," he said. "However, this outcome is dependent on doctors keeping a close eye on the patient after treatment, with regular screenings and early detection of any recurrence."

Dr. Holmes and his colleagues from the Van Nuys Breast Center and USC Norris Comprehensive Cancer Center and Hospital (led by Melvin J. Silverstein, MD) studied data from 1,136 patients who had been treated for DCIS and followed for 10 years. Treatment started as far back as 1971. Among these patients, 236 had a lumpectomy followed by postoperative radiotherapy, 444 received lumpectomy only, and 406 underwent mastectomy.

After 10 years, 129 patients (11.4%) had a recurrence: 18% of the lumpectomy/radiotherapy patients, 30% of the lumpectomy-only patients, and 1.8% of the mastectomy patients. Invasive recurrences were reported in 57 patients (2%, 1.2%, and 1%, respectively). The researchers reported eight breast-cancer-related deaths: six (2%) in the lumpectomy/radiotherapy patients, and two (0.7%) in the lumpectomy-only group. There were no breast-cancer-related deaths reported in the mastectomy group.

"These results show that nearly all patients with DCIS whose cancer recurs can be treated successfully, whether DCIS recurs as a new DCIS or an invasive cancer," Dr. Holmes concluded. "In the small subgroup of patients who develop invasive breast cancer, the chances of surviving 10 years are better than 90%. This is similar to patients diagnosed with small (T1a or T1b) node-negative cancers."

He noted that many studies comparing mastectomy with breast conservation show that mastectomy is associated with a lower risk of local recurrence. "But mastectomy does not provide a survival advantage when compared to breast-conservation therapy," he said. "Our findings show that 730 additional mastectomies would have to be performed to achieve a breast-cancer-specific mortality rate of zero in woman diagnosed with DCIS."

Dr. Holmes believes that this mastectomy rate is unattainable, because mastectomy "may be an undesirable option for many women who are willing to accept a higher risk of local recurrence as long as it does not place them at a higher risk of death."

Careful Monitoring

The successes reported by Dr. Holmes’ team are gained by carefully monitoring patients after treatment. "Patients treated for DCIS in our institution are closely screened for recurrences, regardless of the treatment they received," he said. For patients treated by lumpectomy alone or lumpectomy and postoperative radiotherapy, follow-up includes mammography of the treated breast twice a year for the first 5 years, followed by annual mammography. Any abnormality is evaluated with additional imaging, and suspicious findings are biopsied.

Although mammography can detect 83% of DCIS cases, this method is not fault proof. Magnetic resonance imaging (MRI) has been better in predicting multifocality. "We are now also using MRI to evaluate patients for recurrence," Dr. Holmes said.

As a result of this rigorous follow-up, invasive recurrences are more likely to be diagnosed when they are quite small and confined to the breast. "When treated in this stage, survival rates are excellent," he said.