High-Risk Women Should Stagger Breast Tests
CancerWise - March 2009
For women at high risk for breast cancer, alternating mammograms and magnetic resonance imaging (MRI) every six months, instead of having both once a year, may offer the best chance of catching tumors.
Researchers from M. D. Anderson reported this study at the Cancer Therapy and Research Center-American Association for Cancer Research (CTRC-AACR) San Antonio Breast Cancer Symposium in December 2008.
Significance of research
Annual breast cancer screening for women who are at high risk typically includes a mammogram and MRI along with a breast examination.
"We wanted to test the effectiveness of alternating between a mammogram and a breast MRI every six months,” says Huong Le-Petross, M.D., assistant professor in the Department of Diagnostic Radiology at M. D. Anderson and the study's first author. “This way a woman receives an imaging modality screening every six months."
MRI is known to be more sensitive in detecting certain breast cancers than mammography, but MRI is more expensive.
“To date, the mammogram is the only imaging modality proven to have an impact on mortality,” Le-Petross says. “We do not have long-term follow-up information on MRI yet.”
Researchers Le-Petross and Banu Arun, M.D., associate professor and director of the High-Risk Breast Clinic and co-medical director of Clinical Cancer Genetics at M. D. Anderson, looked at the medical records of 334 women in a cancer-screening program for women at high risk for breast cancer between 1997 through 2007.
The women were considered to be at high risk if they had:
- Hereditary breast and ovarian cancer syndrome
- Personal history of breast cancer
- Atypia or lobular carcinoma in situ (LCIS)
- 20% or higher lifetime risk of breast cancer
Of these women, 86 (26%) alternated mammograms and MRIs every six months. They completed between one and four screening cycles.
- 46% completed the first cycle
- 28% completed the second cycle
- 13% completed the third cycle
- 4% completed the fourth cycle
The other 248 women had prophylactic mastectomy (surgical removal of a non-cancerous breast) or took chemoprevention medication.
All study participants were given clinical breast exams every six months. They were followed for an average of two years.
The alternating MRI and mammography screening program detected nine cancers.
- Five invasive ductal carcinomas
- Three invasive lobular carcinomas
- Two ductal carcinomas in situ
Of these cancers:
- Five (55%) were found by MRI but not mammography
- Three (33%) were found by MRI and mammography
- One (11%) cancer was not found by either technique
- None were detected by mammography alone
In five of the eight cancers found by MRI, the mammogram six months earlier was normal or suggested benign findings.
"The global picture is that MRI can pick up cancers that mammography cannot," Le-Petross says. "This would suggest it’s more beneficial for high-risk patients to have screening MRIs so we can pick up small lesions before a mammogram can detect them."
Researchers are not certain if alternating MRI and mammography will save lives.
"That’s going to take a 10-year follow-up to determine," Le- Petross says. "It’s an exciting question because mammography has always been the gold-standard examination, and now we are challenging that standard."
— Adapted by Dawn Dorsey from an M. D. Anderson news release