Overdiagnosis by breast MRI Francesco Sardanelli Main ... - Geyseco

Overdiagnosis by breast MRI
Francesco Sardanelli
Main objective. To illustrate the potential for overdiagnosis due to breast MRI.
Discussion. Overdiagnosis should be considered for MRI indications in which lesions are diagnosed which
would have been undetected using only conventional imaging (mammography and/or ultrasound). This is
intrinsically associated with MRI screening, recommended for high-risk women. However, high-risk cohort
studies showed early stage of MRI-diagnosed cancers with a high rate of negative nodal status (1-6), which
plays in favor of an outcome effect (using assumptions derived from mammographic screening in the
general female population). On the other hand, the relatively higher probability of triple negative cancers in
these women (in particular BRCA1 mutation carriers) should be taken also into account. Meta-analyses
showed that the risk of overdiagnosis is more important for preoperative MRI which changes 16.6% of
surgical treatments: 9.2% increase of mastectomies due to 8.1% for true positives plus 1.1% for false
positives; 7.4% wider/additional excisions due to 3.0% plus 4.4%, respectively (7). Moreover, pMRI yields a
4.1% incremental detection rate of contralateral cancers (positive predictive value 48%); 35% DCIS and 65%
invasive (mainly node negative) (8). To reduce overtreatment, we need needle imaging-guided needle
sampling (including MRI guidance), reaching 13% of MRI-induced correct changes of surgical planning, to be
compared with only about 1% annual risk of recurrences (but also with 20-40% rate of positive surgical
margins). For contralateral cancers, needle biopsy can also reduce overtreatment, allowing to excise
contralateral cancers with simultaneous conservative surgery in 4% of the women, to be compared with
only 0.5-1% annual risk for contralateral cancer (9). A smart way to deal with MRI additional findings in the
preoperative setting has been recently proposed: to ignore MRI-only findings distant from the index lesions
when they cannot be detected by second look sonography which allows for needle sampling (10, 11).
Preoperative MRI has also been shown to detect extensive intraductal component, but with 11-28%
overestimate and 17-28% underestimate (4). Finally we should take into account that two recent
randomized controlled trials failed to demonstrate advantages from preoperative MRI in terms of
significantly reduced rate of reoperation for cancer involvement of surgical margins at pathology (12, 13).
Even though relevant criticisms can be raised about these two trials, these results should be considered.
Radiologists should be aware that the use of preoperative MRI implies a not negligible risk of overdiagnosis
and overtreatment. A strict and effective relation between radiologists and surgeons is a key point in this
setting.
References
1. Sardanelli F, Podo F. Breast MR imaging in women at high-risk of breast cancer. Is something changing in early
breast cancer detection? Eur Radiol 2007;17(4):873-87.
2. Saslow D, Boetes C, Burke W, et al; American Cancer Society Breast Cancer Advisory Group. American Cancer
Society guidelines for breast screening with MRI as an adjunct to mammography. CA Cancer J Clin 2007;57(2):75-
89.
3. Lord SJ, Lei W, Craft P, et al. A systematic review of the effectiveness of magnetic resonance imaging (MRI) as an
addition to mammography and ultrasound in screening young women at high risk of breast cancer. Eur J Cancer.
2007;43(13):1905-17.
4. Sardanelli F, Boetes C, Borisch B, et al. Magnetic resonance imaging of the breast: recommendations from the
EUSOMA working group. Eur J Cancer 2010;46(8):1296-316.
5. Kuhl C, Weigel S, Schrading S, et al. Prospective multicenter cohort study to refine management recommendations
for women at elevated familial risk of breast cancer: the EVA trial. J Clin Oncol 2010;28(9):1450-7.
6. Sardanelli F, Podo F, Santoro F, et al; High Breast Cancer Risk Italian 1 (HIBCRIT-1) Study. Multicenter surveillance
of women at high genetic breast cancer risk using mammography, ultrasonography, and contrast-enhanced
magnetic resonance imaging (the high breast cancer risk italian 1 study): final results. Invest Radiol 2011;46(2):94-
105.
7. Houssami N, Ciatto S, Macaskill P, et al. Accuracy and surgical impact of magnetic resonance imaging in breast
cancer staging: systematic review and meta-analysis in detection of multifocal and multicentric cancer.
J Clin Oncol 2008 ;26(19):3248-58.

8. Brennan ME, Houssami N, Lord S, et al. Magnetic resonance imaging screening of the contralateral breast in
women with newly diagnosed breast cancer: systematic review and meta-analysis of incremental cancer detection
and impact on surgical management. J Clin Oncol. 2009 Nov 20;27(33):5640-9.
9. Sardanelli F. Overview of the role of pre-operative breast MRI in the absence of evidence on patient outcomes.
Breast 2010 ;19(1):3-6.
10. Elshof LE, Rutgers EJ, Deurloo EE, et al. A practical approach to manage additional lesions at preoperative breast
MRI in patients eligible for breast conserving therapy. Breast Cancer Res Treat 2010;124(3):707-15
11. Sardanelli F. Additional findings at preoperative MRI: a simple golden rule for a complex problem? Breast Cancer
Res Treat 2010;124(3):717-21.
12. Turnbull L, Brown S, Harvey I, et al. Comparative effectiveness of MRI in breast cancer (COMICE) trial: a
randomised controlled trial. Lancet 2010;375(9714):563-71.
13. Peters NH, van Esser S, van den Bosch MA, et al. Preoperative MRI and surgical management in patients with
nonpalpable breast cancer: The MONET - Randomised controlled trial. Eur J Cancer 2011;47(6):879-86.