SAN DIEGO – Short-interval mammography following breast-conserving therapy is not more effective than annual screening mammography in detecting new ipsilateral invasive breast cancer, results from a large health care system study demonstrated.
The National Comprehensive Cancer Network recommends a mammogram 6-12 months following radiation, whereas the American Society of Clinical Oncology recommends the first posttreatment mammogram 1 year after diagnosis, but no earlier than 6 months after completion of radiotherapy, Dr. William T. Sause said at the annual meeting of the American Society for Radiation Oncology.
For the past 10 years Dr. Sause and his associates at Intermountain Healthcare, an organization of 24 hospitals in Utah, have conducted posttreatment mammograms at 6-month intervals for the first 2 years after patients have completed radiotherapy, followed by annual screening. The researchers use mammography tracking software that has been implemented and standardized at all facilities.
To evaluate the effectiveness of this approach, Dr. Sause and his associates reviewed the records of 1,454 patients who had a lumpectomy and radiation between 2003 and 2007. Of those, 1,386 underwent short-interval mammography. All recurrences were reviewed by a dedicated breast radiologist to verify the recurrence, type, and diagnosis.
Dr. Sause reported that 25 patients (1.8%) experienced a recurrence during the study period. Most recurrences (84%) manifested within 24 months, "which is not surprising, because our study closed in 2007, so the follow-up isn’t much longer than that," he said.
Nearly half of the recurrences (44%) were ductal in situ carcinoma, and 52% occurred in the ipsilateral breast. Of the ipsilateral breast recurrences, 62% were ductal in situ carcinoma.
No ipsilateral or invasive recurrences were identified within 12 months. Five (20%) ipsilateral and invasive recurrences were identified at 12-24 months, for a relative risk of 0.4%. The researchers found that the screening efficacy for patients undergoing short-term mammography is significantly lower compared with that of the general screening population (a yield of 2.9 vs. 4.4 cancers per 1,000 patients, respectively).
"Short-term mammography following modern breast conservation has very low yield for new ipsilateral invasive breast cancer," Dr. Sause concluded. "Eliminating short-term mammography would result in a minimum direct cost savings of approximately $1,160,000 for this patient cohort over the study period."
He said that the analysis "represents a worthwhile demonstration of comparative effectiveness research and has potential to be expanded to other treatment areas."
Electronic data resources, clinical leadership, data and statistical support, and cultural reorganization of priorities are needed for effective comparative effectiveness research, he continued. "All of these are challenging," he acknowledged. "There are misaligned incentives between health care providers and payers. It’s very easy for me to challenge the utilization of mammography. It’s not so easy to challenge the utilization of IMRT [intensity-modulated radiation therapy]."
Dr. Sause said that he had no relevant financial disclosures.