Should women at high risk of breast cancer have screening magnetic resonance imaging (MRI)?

DNA damage induced by mammography in high family risk patients: only one single view in screening

Women with high risk of breast or ovarian cancers might be more susceptible to radiation-induced cancer because most of tumor suppressor genes are also implicated in the radio-induced DNA damage repair and signaling. Recent radiobiological advances may help to re-consider the potential cellular and molecular consequences of the standard two-view mammographic screening. A major radiobiological effect exacerbated in high family risk women caused by mammographic repeated doses was pointed out on relevant cellular model (untransformed and non tumoral human breast epithelial cells): the Low and Repeated Dose (LORD) effect. In parallel, while magnetic resonance imaging (MRI) is reported to be less sensitive than mammography for detection of ductal carcinoma in situ, a recent study highlighted the increased ability of MRI to detect them related to the experience both of radiologists and MRI centers. Hence, along with studies confirming improvement of the sensitivity of MRI to detect ductal carcinoma in situ, the supra-additivity effect induced by the two-view mammographic screening in high family risk patients suggests that mammographic exposures can be limited seriously. Consequently, a single view (oblique) per breast in association with annual MRI, with the sole aim to detect calcifications reflecting carcinoma in situ non detectable by MRI, might represent currently a compromise.

High cancer yield and positive predictive value: outcomes at a center routinely using preoperative breast MRI for staging

OBJECTIVE

The purpose of our study is to report the outcomes at a center that routinely uses breast MRI for preoperative staging, regardless of lesion histology or patient characteristics.

MATERIALS AND METHODS

Five hundred ninety-two patients with recently diagnosed breast cancer who underwent staging with preoperative breast MRI between January 1, 2003, and April 30, 2007, were reviewed. Five hundred seventy patients comprised the analysis set. Patient age, breast density, index tumor histology, receptor status (ER, PR, and HER2), and lymph node status were recorded. Biopsy rates, positive predictive values (PPVs) of biopsy, and overall cancer yield were calculated and compared using the chi-square test across patient age, mammographic breast density, index tumor type, receptor status, and lymph node status.

RESULTS

Biopsy was recommended and performed for 152 of 570 (27%) patients found to have one or more suspicious lesions on MRI distinct from the index cancer. Sixty-seven of 152 women who underwent biopsy had additional cancers diagnosed, for a PPV of 44%. Overall, 12% (67/570) of women had otherwise occult cancers diagnosed by MRI, with 8% having additional sites or greater extent of ipsilateral disease and 4% having unsuspected contralateral cancer detected by MRI alone. No significant differences were found in the probability of detecting an occult cancer on the basis of patient age, breast density, index tumor characteristics, or lymph node status.

CONCLUSION

Breast MRI detects otherwise occult cancer with an overall added cancer yield of 12% and a high PPV of 44% when applied to a diverse population of patients with newly diagnosed breast cancer.

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

Breast magnetic resonance imaging (MRI) has been proposed as an additional screening test for young women at high risk of breast cancer in whom mammography alone has poor sensitivity. We conducted a systematic review to assess the effectiveness of adding MRI to mammography with or without breast ultrasound and clinical breast examination (CBE) in screening this population. We found consistent evidence in 5 studies that adding MRI provides a highly sensitive screening strategy (sensitivity range: 93-100%) compared to mammography alone (25-59%) or mammography plus ultrasound+/-CBE (49-67%). Meta-analysis of the three studies that compared MRI plus mammography versus mammography alone showed the sensitivity of MRI plus mammography as 94% (95%CI 86-98%) and the incremental sensitivity of MRI as 58% (95%CI 47-70%). Incremental sensitivity of MRI was lower when added to mammography plus ultrasound (44%, 95%CI 27-61%) or to the combination of mammography, ultrasound plus CBE (31-33%). Estimates of screening specificity with MRI were less consistent but suggested a 3-5-fold higher risk of patient recall for investigation of false positive results. No studies assessed as to whether adding MRI reduces patient mortality, interval or advanced breast cancer rates, and we did not find strong evidence that MRI leads to the detection of earlier stage disease. Conclusions about the effectiveness of MRI therefore depend on assumptions about the benefits of early detection from trials of mammographic screening in older average risk populations. The extent to which high risk younger women receive the same benefits from early detection and treatment of MRI-detected cancers has not yet been established.