MRI in Breast Cancer
http://www.100md.com
《新英格兰医药杂志》
To the Editor: Kriege et al. (July 29 issue)1 show that magnetic resonance imaging (MRI) appears to be more sensitive than mammography in detecting tumors in women with an inherited susceptibility to breast cancer. The study design specified that both imaging techniques (mammography and MRI) were judged independently by two radiologists in each center.2 Our concern is that central review of the radiologic findings for the determination of concordance would have been better, given the aim of the study.
Kadri Altundag, M.D.
Hacettepe University Faculty of Medicine
06100 Ankara, Turkey
drkadri@usa.net
Paolo Morandi, M.D.
S. Bortolo General Hospital
36100 Vicenza, Italy
Ozden Altundag, M.D.
Hacettepe University Faculty of Medicine
06100 Ankara, Turkey
References
Kriege M, Brekelmans CT, Boetes C, et al. Efficacy of MRI and mammography for breast-cancer screening in women with a familial or genetic predisposition. N Engl J Med 2004;351:427-437.
Kriege M, Brekelmans CT, Boetes C, et al. MRI screening for breast cancer in women with familial or genetic predisposition: design of the Dutch National Study (MRISC). Fam Cancer 2001;1:163-8.
To the Editor: The study by Kriege et al. highlights the methodologic difficulties in prospectively comparing various types of diagnostic techniques. First, the results of mammography were confounded by the fact that the majority of women had undergone prior mammography (not prior MRI). Hence, a higher yield of breast cancers was seen only with MRI during the initial screening. This is reflected by the change in the sensitivity of MRI, but not of mammography, during the second screening, possibly resulting in a bias against mammography. Second, both the receiver-operating-characteristic curves and the differences in specificity suggest that the comparison would be more appropriate when the radiologists are more conservative during mammography and recommend follow-up for lower levels of suspicion, as they would do during regular mammographic screening. The more appropriate comparison with MRI in this case would be mammography (perhaps digital mammography) at 90 percent specificity (not 95 percent). If rates of cancer detection are correlated with recommendations for additional procedures,1,2 the findings on mammograms could be substantially different. MRI is probably more effective than mammography in detecting early breast cancers in this group of women; however, the actual differences between mammography and MRI may be substantially lower than this study suggests.
David Gur, Sc.D.
University of Pittsburgh
Pittsburgh, PA 15213
gurd@upmc.edu
References
Yankaskas BC, Cleveland RJ, Schell MJ, Kozar R. Association of recall rates with sensitivity and positive predictive values of screening mammography. AJR Am J Roentgenol 2001;177:543-549.
Gur D, Sumkin JH, Hardesty LA, et al. Recall and detection rates in screening mammography. Cancer 2004;100:1590-1594.
The authors reply: In our opinion, an independent judgment is essential for comparing the value of screening tests. To guarantee this independent judgment in our study, MRI and mammography were evaluated by different radiologists. An evaluation of both MRI and mammography by the same radiologist, without knowledge of the results of the other screening technique, would have been better. As Altundag and colleagues suggest, a central review of the radiologic findings could resolve discrepancies between radiologists who assess mammographic or MRI findings. This approach is being used now.
We agree with Gur that the difference in sensitivity between mammography and MRI might be artificially increased by the fact that the majority of women underwent prior mammography but not prior MRI. However, in the subsequent rounds of our study, MRI was also more sensitive than mammography with respect to invasive tumors (76.5 percent vs. 29.4 percent, P=0.02; unpublished data). The imaging in our study was evaluated according to the Breast Imaging Reporting and Data System.1,2 We agree that comparing the sensitivity of screening tests is most appropriate at the same specificity, which was made possible by the receiver-operating-characteristic curves that were constructed. In our opinion, these curves show clearly that, at a wide range of specificity values, MRI is superior to mammography. This is also shown in Table 3 of our article.
Mieke Kriege, M.Sc.
Cecile T.M. Brekelmans, M.D., Ph.D.
Jan G.M. Klijn, M.D., Ph.D.
Erasmus Medical Center
3075 EA Rotterdam, the Netherlands
j.g.m.klijn@erasmusmc.nl
References
Illustrated breast imaging reporting and data system (BI-RADS). 3rd ed. Reston, Va.: American College of Radiology, 1995.
Liberman L, Menell JH. Breast imaging reporting and data system (BI-RADS). Radiol Clin North Am 2002;40:409-430.
Kadri Altundag, M.D.
Hacettepe University Faculty of Medicine
06100 Ankara, Turkey
drkadri@usa.net
Paolo Morandi, M.D.
S. Bortolo General Hospital
36100 Vicenza, Italy
Ozden Altundag, M.D.
Hacettepe University Faculty of Medicine
06100 Ankara, Turkey
References
Kriege M, Brekelmans CT, Boetes C, et al. Efficacy of MRI and mammography for breast-cancer screening in women with a familial or genetic predisposition. N Engl J Med 2004;351:427-437.
Kriege M, Brekelmans CT, Boetes C, et al. MRI screening for breast cancer in women with familial or genetic predisposition: design of the Dutch National Study (MRISC). Fam Cancer 2001;1:163-8.
To the Editor: The study by Kriege et al. highlights the methodologic difficulties in prospectively comparing various types of diagnostic techniques. First, the results of mammography were confounded by the fact that the majority of women had undergone prior mammography (not prior MRI). Hence, a higher yield of breast cancers was seen only with MRI during the initial screening. This is reflected by the change in the sensitivity of MRI, but not of mammography, during the second screening, possibly resulting in a bias against mammography. Second, both the receiver-operating-characteristic curves and the differences in specificity suggest that the comparison would be more appropriate when the radiologists are more conservative during mammography and recommend follow-up for lower levels of suspicion, as they would do during regular mammographic screening. The more appropriate comparison with MRI in this case would be mammography (perhaps digital mammography) at 90 percent specificity (not 95 percent). If rates of cancer detection are correlated with recommendations for additional procedures,1,2 the findings on mammograms could be substantially different. MRI is probably more effective than mammography in detecting early breast cancers in this group of women; however, the actual differences between mammography and MRI may be substantially lower than this study suggests.
David Gur, Sc.D.
University of Pittsburgh
Pittsburgh, PA 15213
gurd@upmc.edu
References
Yankaskas BC, Cleveland RJ, Schell MJ, Kozar R. Association of recall rates with sensitivity and positive predictive values of screening mammography. AJR Am J Roentgenol 2001;177:543-549.
Gur D, Sumkin JH, Hardesty LA, et al. Recall and detection rates in screening mammography. Cancer 2004;100:1590-1594.
The authors reply: In our opinion, an independent judgment is essential for comparing the value of screening tests. To guarantee this independent judgment in our study, MRI and mammography were evaluated by different radiologists. An evaluation of both MRI and mammography by the same radiologist, without knowledge of the results of the other screening technique, would have been better. As Altundag and colleagues suggest, a central review of the radiologic findings could resolve discrepancies between radiologists who assess mammographic or MRI findings. This approach is being used now.
We agree with Gur that the difference in sensitivity between mammography and MRI might be artificially increased by the fact that the majority of women underwent prior mammography but not prior MRI. However, in the subsequent rounds of our study, MRI was also more sensitive than mammography with respect to invasive tumors (76.5 percent vs. 29.4 percent, P=0.02; unpublished data). The imaging in our study was evaluated according to the Breast Imaging Reporting and Data System.1,2 We agree that comparing the sensitivity of screening tests is most appropriate at the same specificity, which was made possible by the receiver-operating-characteristic curves that were constructed. In our opinion, these curves show clearly that, at a wide range of specificity values, MRI is superior to mammography. This is also shown in Table 3 of our article.
Mieke Kriege, M.Sc.
Cecile T.M. Brekelmans, M.D., Ph.D.
Jan G.M. Klijn, M.D., Ph.D.
Erasmus Medical Center
3075 EA Rotterdam, the Netherlands
j.g.m.klijn@erasmusmc.nl
References
Illustrated breast imaging reporting and data system (BI-RADS). 3rd ed. Reston, Va.: American College of Radiology, 1995.
Liberman L, Menell JH. Breast imaging reporting and data system (BI-RADS). Radiol Clin North Am 2002;40:409-430.