乳がん既往歴を有する女性はMRIでスクリーニングすべきである

乳房MRIは乳がん遺伝歴または家族歴を有する女性よりも乳がん既往歴を有する女性に対しより多くの乳がんを検出し偽陽性は少ない
Breast MRI identified more cancers with fewer false positives in women with a personal history of breast cancer than in women with a genetic or family history
乳がん既往歴を有する女性には年1回のマンモグラフィーに加えMRIによるスクリーニングも考慮すべきであるとのスタディ結果が2010年RSNAで発表された。研究者らは、2004年1月から2009年6月にかけて女性1,026人の初回スクリーニング乳房MRI検査の結果をレトロスペクティブ解析した；327人が乳がん遺伝歴または家族歴を有しており、646人が乳がん治療歴を有していた。全体で、MRI検査によりこの患者グループの27件のがんのうち25件が検出され、感度は92.6%であった。乳がん既往歴を有する女性の乳がん発症率（3.1%）は遺伝歴または家族歴を有する女性（1.5%）の倍であった。乳がん既往歴を有する女性における特異度は93.6%であり、これと比較し、他の群の特異度は86.3%であった。生検を勧められたのは乳がん既往歴を有する女性の9.3%であり、遺伝歴および家族歴を有する女性におけるその割合は15%であった。生検の陽性適中率もまた、乳がん既往歴群において高く、生検の35.7%からがんが検出されたのに対し他の群では12.2%であった。
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Women with a personal history of breast cancer should consider annual screening with MRI in addition to mammography, according to a study presented at the 2010annual meeting of the Radiological Society of North America (RSNA).

The American Cancer Society (ACS) guidelines currently recommend annual screening with breast MRI in women with a known gene mutation or with a strong family history indicating a lifetime risk of breast cancer greater than 20 percent. However, the guidelines say there is insufficient evidence to recommend for or against MRI screening in women who have already had breast cancer themselves.

"In our study using breast MRI screening, we actually detected proportionally more cancers in women with a personal history of breast cancer, compared with those women with a genetic mutation or strong family history who are currently recommended to have breast MRI," said Wendy B. DeMartini, M.D., assistant professor in the Department of Radiology at the University of Washington Medical Center and Seattle Cancer Care Alliance in Seattle. "Further, women with a personal history were less likely to be recalled for additional testing and less likely to have a biopsy for a false positive MRI finding."

Dr. DeMartini and colleagues performed a retrospective review of initial screening breast MRI examinations of 1,026 women from January 2004 to June 2009. Of the 1,026 women, 327 had a genetic or family history of breast cancer and 646 had a personal history of treated breast cancer.

Overall, MRI testing identified 25 of 27 cancers in the group for a sensitivity rate of 92.6 percent.

The cancer yield in the women with a personal history of breast cancer (3.1 percent) was double that of the women with a genetic or family history (1.5 percent). Specificity in women with a personal history was 93.6 percent, compared with 86.3 percent for the other group.

Biopsy was recommended in 9.3 percent of the women with a personal history of breast cancer, compared with 15 percent of the genetic and family history group. The positive predictive value of biopsy was also higher in the personal history group, with 35.7 percent of biopsies yielding cancer, compared with only 12.2 percent in the other group.

"Our findings show that the diagnostic performance of MRI in patients with a personal history of treated breast cancer supports consideration of screening MRI as an adjunct to mammography," Dr. DeMartini said. "Additional studies such as ours are necessary to establish guidelines for screening this important group of women."

Coauthors are Grace Kalish, M.D., Sue Peacock, M.Sc., Peter Eby, M.D., Robert Gutierrez, M.D., and Constance Lehman, M.D., Ph.D.