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MRI Better Than Mammography in Older Women


 

CHICAGO — Magnetic resonance imaging can detect cancer that is missed by mammography and physical examination in women aged 70 years or older, a retrospective single-institution study suggests.

The review of 159 elderly women with newly diagnosed breast cancer found MRI detected a contralateral cancer in 9 patients, even when mammography and palpation failed to do so, Dr. Johnny R. Bernard Jr. reported at the annual meeting of the American Society of Clinical Oncology.

Breast cancer risk increases with age, so that by the time a woman reaches age 70, she has a 1 in 15 chance of developing invasive breast cancer. Women with newly diagnosed breast cancer are also at high risk for having cancer in the contralateral breast. This combination of factors makes elderly women a high-risk cohort likely to benefit from enhanced screening with MRI, said Dr. Bernard, of the Mayo Clinic in Jacksonville, Fla.

The review included 159 women aged 70 or older (median age 75, range 70-91 years) at the time of their breast cancer diagnosis who had no evidence of cancer in the contralateral breast by mammogram or physical examination. All of the women had bilateral breast MRI between 2003 and 2007 at the Mayo Clinic's Jacksonville campus.

Mammographically occult contralateral abnormalities were noted in 65 of the women, and a biopsy was performed in 28 by Mayo Clinic pathologists. Nine of the 28 biopsies (32%) revealed pathologically confirmed carcinomas; 5 had invasive ductal carcinomas and 4 had ductal carcinomas in situ. All were node-negative stage 0-1 cancers. The other 18 biopsies were benign, for an overall prevalence of mammographically occult contralateral carcinoma of 6% for the study population as a whole, Dr. Bernard said.

MRI performed very well in this population, he added, with both sensitivity and negative predictive value of 100%. Specificity was 87%, and positive predictive value was 32%. “We recommend that older women should not be discriminated against with regard to breast MRI. At this time, we consider contralateral MRIs the standard of care at our institution,” he said.

In the question-and-answer period, Dr. Bernard was asked about the potential hazards of MRI screening in older women, such as overdiagnosis, unnecessarily aggressive treatment, and increased patient anxiety. He said these risks are well known, but that older women deserve the same considerations as younger women.

“We know from social security life tables that women who are aged 70 have a life expectancy of about 16 years; a woman of age 80 has a life expectancy of 10 years, age 85, it is 7.2 years,” he said. “If a woman has no significant comorbidities, or has minimal comorbidities, and if she has a life expectancy of at least 5 years, she is expected to benefit from screening mammography. We feel women will also benefit from screening MRI.”

He added that risks and benefits of treatment are always discussed beforehand. “We allow our patients to participate in our decision-making process,” he said.

Discussant Dr. Robyn L. Birdwell, of Harvard Medical School and Brigham & Women's Hospital in Boston, underscored Dr. Bernard's comments about offering older women the same screening options as younger women.

“Both patients and their physicians underestimate life expectancy in women,” she said. “In the healthy population of older women, 15 years is quite a bit of time to expect, and we need to be aware of this tendency to underestimate life expectancy.”

She predicted that MRI screening for breast cancer would be increasingly used in women who are recognizable as high risk, such as the elderly.

Neither Dr. Bernard nor Dr. Birdwell disclosed any conflicts of interest.

'At this time, we consider contralateral MRIs the standard of care at our institution.' DR. BERNARD

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