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

Screening and prevention of breast cancer in primary care

Mammography remains the mainstay of breast cancer screening. There is little controversy that mammography reduces the risk of dying from breast cancer by about 23% among women between the ages of 50 and 69 years, although the harms associated with false-positive results and overdiagnosis limit the net benefit of mammography. Women in their 70s may have a small benefit from screening mammography, but overdiagnosis increases in this age group as do competing causes of death. While new data support a 16% reduction in breast cancer mortality for 40- to 49-year-old women after 10 years of screening, the net benefit is less compelling in part because of the lower incidence of breast cancer in this age group and because mammography is less sensitive and specific in women younger than 50 years. Digital mammography is more sensitive than film mammography in young women with similar specificity, but no improvements in breast cancer outcomes have been demonstrated. Magnetic resonance imaging may benefit the highest risk women. Randomized trials suggest that self-breast examination does more harm than good. Primary prevention with currently approved medications will have a negligible effect on breast cancer incidence. Public health efforts aimed at increasing mammography screening rates, promoting regular exercise in all women, maintaining a healthy weight, limiting alcohol intake, and limiting postmenopausal hormone therapy may help to continue the recent trend of lower breast cancer incidence and mortality among American women.

Temporal sampling requirements for reference region modeling of DCE-MRI data in human breast cancer

PURPOSE

To assess the temporal sampling requirements needed for quantitative analysis of dynamic contrast-enhanced MRI (DCE-MRI) data with a reference region (RR) model in human breast cancer.

MATERIALS AND METHODS

Simulations were used to study errors in pharmacokinetic parameters (K(trans) and v(e)) estimated by the RR model using six DCE-MRI acquisitions over a range of pharmacokinetic parameter values, arterial input functions, and temporal samplings. DCE-MRI data were acquired on 12 breast cancer patients and parameters were estimated using the native resolution data (16.4 seconds) and compared to downsampled 32.8-second and 65.6-second data.

RESULTS

Simulations show that, in the majority of parameter combinations, the RR model results in an error less than 20% in the extracted parameters with temporal sampling as poor as 35.6 seconds. The experimental results show a high correlation between K(trans) and v(e) estimates from data acquired at 16.4-second temporal resolution compared to the downsampled 32.8-second data: the slope of the regression line was 1.025 (95% confidence interval [CI]: 1.021, 1.029), Pearson's correlation r = 0.943 (95% CI: 0.940, 0.945) for K(trans), and 1.023 (95% CI: 1.021. 1.025), r = 0.979 (95% CI: 0.978, 0.980) for v(e). For the 64-second temporal resolution data the results were: 0.890 (95% CI: 0.894, 0.905), r = 0.8645, (95% CI: 0.858, 0.871) for K(trans), and 1.041 (95% CI: 1.039, 1.043), r = 0.970 (95% CI: 0.968, 0.971) for v(e).

CONCLUSION

RR analysis allows for a significant reduction in temporal sampling requirements and this lends itself to analyze DCE-MRI data acquired in practical situations.

Interaction of gadolinium-based MR contrast agents with choline: implications for MR spectroscopy (MRS) of the breast

It has been shown that magnetic resonance spectroscopy (MRS) can improve the specificity of the MR examination by the spectroscopic detection of choline (Cho). Commonly, the lesion is first visualized on postcontrast studies, and the MRS voxel is prescribed accordingly. The implicit assumption made in this approach is that the presence of gadolinium-based contrast agents will have a negligible effect on the MR spectra obtained from the lesion. In this work, we examined this assumption by determining the effects of six gadolinium-based contrast agents: Magnevist, Multihance, Omniscan, Optimark, ProHance, and Dotarem, on the Cho peak in phantoms and in a rat model for breast cancer. We found that only the three negatively-charged chelates: Magnevist, MultiHance, and Dotarem, broadened the Cho peak in phantoms and reduced the area of the Cho peak in vivo by an average of about 40%. The use of negatively-charged chelates may lead to an underestimation of the levels of Cho present in human breast cancers, since most studies use MRS postcontrast administration. Therefore, we recommend the use of the neutral chelates in MRI/MRS studies of the breast.

Breast cancer screening: emerging role of new imaging techniques as adjuncts to mammography

Early detection of breast cancer has been shown to reduce breast cancer deaths in randomised controlled trials (RCTs) of mammography in women aged 50-69 years, with weaker evidence of benefit in those aged 40-49 or 70 years and older. Magnetic resonance imaging (MRI) and ultrasonography have been evaluated in breast cancer screening, relative to, or in addition to, mammography, in selected populations; neither test has been examined in an RCT, and thus evidence of associated screening benefit is uncertain. MRI is more sensitive than mammography in screening women with suspected or proven inherited mutations of the breast cancer genes. The addition of MRI in screening this population detects 8-24 additional cancers per 1000 screens, but also significantly increases a woman's risk of being recalled for investigation or surgical biopsy for false-positive findings. In Australia, Medicare funding for MRI screening of women in specific risk groups was announced in February 2009. Ultrasonography can detect cancers not identified on mammography in asymptomatic women with dense breast tissue. Incremental ultrasound cancer detection is reported in 0.27%-0.46% of women with mammography-negative dense breasts; evidence varies on its association with false-positive findings. Computer-aided detection (CAD) is a complementary tool to mammography, prompting the reader to consider lesions on the mammogram that may represent cancer. Emerging evidence and improved CAD technology are likely to help define its role in breast screening.

Estimated risk of radiation-induced breast cancer from mammographic screening for young BRCA mutation carriers

BRCA mutation carriers are recommended to start mammographic screening for breast cancer as early as age 25-30 years. We used an excess relative risk model (based on a pooled analysis of three cohorts with 7600 subjects who received radiation exposure) to estimate the lifetime risk of radiation-induced breast cancer from five annual mammographic screenings in young (<40 years) BRCA mutation carriers. We then estimated the reduction in breast cancer mortality required to outweigh the radiation risk. Breast cancer rates for mutation carriers were based on a pooled analysis of 22 pedigree studies with 8139 subjects. For BRCA1 mutation carriers, the estimated lifetime risk of radiation-induced breast cancer mortality per 10,000 women resulting from annual mammography was 26 (95% confidence interval [CI] = 14 to 49) for screening at age 25-29 years, 20 (95% CI = 11 to 39) for screening at age 30-34 years, and 13 (95% CI = 7 to 23) for screening at age 35-39 years. To outweigh these risks, screening would have to reduce breast cancer mortality by 51% (95% CI = 27% to 96%) at age 25-29 years, by 12% (95% CI = 6% to 23%) at age 30-34 years, and by 4% (95% CI = 2% to 7%) at age 35-39 years; estimates were similar for BRCA2 mutation carriers. If we assume that the mortality reduction from mammography is 15%-25% or less for young women, these results suggest that there would be no net benefit from annual mammographic screening of BRCA mutation carriers at age 25-29 years; the net benefit would be zero or small at age 30-34 years, but there should be some net benefit at age 35 or older. These results depend on a number of assumptions due to the absence of empiric data. The impact of varying these assumptions was therefore examined.

Cancer screenings, diagnostic technology evolution, and cancer control

Screening should allow for the anticipation of cancer diagnosis at an earlier stage, when curative treatment is possible. Screening for cervical, large bowel, and breast cancer were shown to be effective in reducing mortality. The wide acceptance of the screening concept led to the wide diffusion also of screening of uncertain benefit against prostate cancer and skin melanoma. Diagnostic technologies are continuously evolving, and new tests are proposed to improve existing screenings or as screening tests for additional cancer sites (e.g., lung cancer). Cancer screening, however, is a complex and costly intervention that does not result only in benefits but also may cause harm. A major emerging problem of screening is overdiagnosis, or the detection of cases that would have not progressed to the symptomatic phase in the absence of screening. Thus, both experimental and observational evaluation studies are needed to reduce harm caused by screenings and to select effective interventions among many proposed innovations. Finally, the research of markers to assess the aggressive nature of screen-detected lesions is of great importance to improve screenings ' harm/benefit ratio.

Breast cancer screening in women at high risk using MRI

A series of prospective comparative studies have demonstrated that MRI has approximately twice the sensitivity of X-ray mammography for screening women at high familial risk of breast cancer. In these studies, lesions have often been detected at an early stage, with disease being small and predominantly node negative. The diagnostic features in relation to risk and the biological behaviour of disease with risk category and age are being evaluated. The results of these studies have resulted in revised recommendations for screening for women at high risk of breast cancer. In this article, the results of the UK Magnetic Resonance Imaging in Breast Cancer Screening (MARIBS) study of MRI screening are described, and compared with results from other studies. Risk factors identifying women who would benefit from MRI screening are discussed, MRI measurement methods are described, and the results of studies evaluating MRI and mammographic lesions in different risk groups are reviewed. Recommendations for screening women at high risk of breast cancer published by the American Cancer Society and from the National Institute for Health and Clinical Excellence (NICE) in the UK are summarised.

Imaging studies for the early detection of breast cancer

INTRODUCTION

The effectiveness of mammographic screening has been proven at evidence level 1A. Mammography offers the best ratio of benefits to side effects of any screening method tested to date. In this literature review, we ask whether early detection might be improved still further by combining mammography with other imaging modalities.

METHODS

The authors performed a selective literature search for combined key words in the Medline and Cochrane Library databases from 1/2000 to 11/2007, screened all titles, and evaluated the full text of all original articles. We selected articles for further analysis according to systematic criteria (minimum numbers, avoidance of overlap) and also considered published guidelines.

RESULTS

No screening studies of comparable size to those for mammography are available for ultrasound or MRI. Smaller studies have indicated that the use of these two modalities might lead to the detection of additional cancers in selected subgroups. For mass screening an increase in the detection rate of 10% to 15% might become possible. This increase would probably be associated with a tripling of the breast biopsy rate, compared to mammography alone. The number of indeterminate cases in which short-term follow-up (i.e., at 6 months) would be recommended would increase roughly tenfold with MRI, and to an unknown extent with ultrasound. The related quality-assurance issues remain to be addressed.

DISCUSSION

Randomized controlled studies are needed for a realistic assessment of the achievable benefits and unavoidable side effects of combined screening. For women whose risk of breast cancer is not elevated, mammography remains the standard screening method.

The utility of MRI for the screening and staging of breast cancer

INTRODUCTION & BACKGROUND

Contrast-enhanced magnetic resonance imaging (MRI) of the breast has been recently introduced as a potential clinical tool for the detection, diagnosis, staging and management of breast cancer. In this article, we consider the established and evolving roles of MRI with particular reference to screening in high risk women and staging of the primary tumour. Controversies are discussed in the context of the tumour biology and natural history of breast cancer.

METHODS

Articles were identified by searches of PubMed and MEDLINE up to October 2007.

RESULTS

Contrast-enhanced MRI is an effective tool for screening women at high risk of breast cancer. However, randomized trials have yet to demonstrate a reduction in mortality. MRI can also facilitate local staging, in particular, the evaluation of ipsilateral multicentric or multifocal lesions and synchronous contralateral disease which may be 'missed' by conventional imaging. However, efficacy with respect to clinically relevant and patient oriented end-points has yet to be addressed in the context of clinical trials.

CONCLUSIONS

In women at high risk of breast cancer, screening MRI should be used in conjunction with published guidelines. In women with newly diagnosed breast cancer, the utility of MRI is less clearly defined and should be restricted to selected cases within the multidisciplinary setting.