Risk of Breast Cancer

Clinical breast examination (CBE), magnetic resonance imagine (MRI) and screening mammography are considered to be the effective tools for detecting occult cancers in women with an increased predilection for the developing of this disease. Mammography was the primary method used for breast cancer screening that has reduced the mortality rate related with the breast cancer by 40%. However, the cases of mammography’s low sensitivity are frequently observed in this group due to a dense breast tissue in younger women. That is why mammography is not considered to be the optimal method for breast cancer screening in young women (Saadatmand, 2012). In other words, mammography detects the breast cancer at later stage. MRI is of greater sensitivity in comparison with the mammography (70% vs 40%). That is why it supplements mammography and CBE for the purpose of better detection (Petross, 2011). The high-risk women must undergo the alternation mammography and MRI biannually in order to facilitate an early detection of the disease. Therefore, the survey is focused on the investigation of the mammography and MRI efficiency in women with the hereditary BRCA. It takes into account the data of other surveys that investigated the question at issue. This was done in order to discuss obtained results in the light of previous studies, explain whether these results prove the general hypothesis and summarize the data.

The efficiency of MRI as a screening modality in women at hereditary risk of breast cancer was assessed through the retrospective reviews in combination with prospectively collected data from women who underwent surveillance MRI at Royal Melbourne Hospital Department of Radiology. The surveillance MRI was claimed to be an effective tool for detecting occult cancers in patients at high risk for developing breast cancer. The higher sensitivity of MRI resulted in a higher biopsy rate. The comparison of the MRI characteristics of the 14 fibro adenomas and 4 cancers showed that it was impossible to distinguish them without biopsy (Kam, Naidu, Rose, Mann, 2013). This data is comparable with the UK study conducted by Leach et al. In 4 out of 32 cases, lesions could not be accurately distinguished with US. As a result MRI-guided biopsy was used at a separate visit.

A single-institution study of the BRCA1 or BRCA2 mutation carriers or their first-degree relatives who attended The University of Texas MD Anderson Cancer Center investigated the efficiency of mammography and MRI for screening women with BRCA mutations. The records of 321 participants with BRCA1 or BRCA2 mutations were reviewed, however only 73 women met strict requirements. All patients were at least 18 years old and undergone the alternating screening and MRI every 6 months. According to The American College of Radiology (ACR), the mammographic breast density was determined as: entirely fatty; fibro glandular density; heterogeneously dense; extremely dense.

The conclusion of the survey was that the difference in sensitivity and specificity between MRI and mammography could not be defined due to that fact that only four out of eleven women obtained mammography study after the screening MRI identified cancer. However, on the basis of the survey, the higher efficiency of MRI in breast cancer detection was obvious in comparison with the mammography (Petross, 2011). Similar findings were observed by Granader et al. in the survey that was conducted on the basis of data from MEDLINE, ACP Journal Club, PubMed, SCOPUS databases. Moreover, the articles on the investigated theme were collected and assessed. The results of the study demonstrated that MRI or the combination of MRI with the mammography were able to show better sensitivity than the mammography by itself. This statement is especially true for patients at hereditary risk of breast cancer or for those who possess BRCA1/2 (Granader, Dwamena, Carlos, 2008).

Despite the fact that MRI beneficial position was proven by a great number of scientists through their numerous studies, however some experts state the opposite. (Morrow, Waters, Morris, 2011) The Dutch MRI Screening Study started in 1999. It divided all participants into subgroups: women with gene mutation, women at high risk of breast cancer and women at moderate risk. It was claimed that the intensive surveillance can identify breast cancer at an early age. Sensitivity and specificity of MRI did not show any differences between the studied subgroups. Moreover, the sensitivity of mammography was higher in BRCA2 cases than in BRCA1 cases. Mammography had a higher sensitivity in DCIS than in invasive tumors. As a result, the sensitivity of MRI was smaller in BRCA2 cases (Rijnsburger, 2010). The similar findings were observed within the MARIBS study. All cases of DCIS were visible on mammography and only two cases on MRI (Thompson, 2009). The UK multicentre magnetic resonance imaging breast screening (MARIBS) study was based on MRI and mammography images. The participants were the patients with BRCA1 and BRCA2 mutations and other women at high risk of breast cancer. In total, 837 asymptomatic women were the participants of the survey. Its aim was to assess the value of the MRI breast density estimation algorithm in women with hereditary risk of breast cancer.

A fatty tissue is separated from tissues of water density resorting to mammography, meanwhile tissue types are differentiated by means of MRI. In case of mammography screening, density estimation is based on a single two-dimensional breast projection, in contrast to the three-dimensional MRI image. Therefore, the quantities estimated by the two methods are different, despite being closely related. High breast density was estimated as one of the risk factors for breast caner. There was no proof of any relationship between breast density and BRCA2 mutation status. Mitchell et al. 2006 did not find any relationship between BRCA1\2 carrier status and Cumulus percent dense area in his study. The association between breast cancer risk and percent density was not found. However, the other important fact was discovered. The results for the MRI percent dense volume and the results for the Cumulus percent dense were the same. Hence, it means that MRI percent density can not be a better predictor of cancer risk than the traditional quantitative mammographic density measures. Although it can be useful for patients with TP53 mutation as x-ray mammography is considered unsafe for them (Thompson, 2009).

Leung et al. wanted to determine whether breast MRI screening is more effective than digital mammography in Taiwanese women. The research was based on the retrospectively collected data on 106 Asian women who undergone both mammography and MRI examinations at the same time. The survey findings indicated that it was difficult to detect breast lesions only by digital mammography. Tthe mammography sensitivity is lower in woman with dense breast tissue (Morrow, Waters, Morris, 2011). The MRI screening was even more sensitive than the combination of mammography and ultrasound. Furthermore, MRI was more accurate in assessing multimodality and tumor extent in women with a dense breast. In addition, a multicentric or multifocal carcinoma was identified by means of: mammography in 35% of cases, ultrasound in 35% of cases and MRI identified 100%. In spite of this fact digital mammography is useful because of its accurate detection in women with NDBPP. Taiwanese women often have dense breasts in the pre-menopausal stage. As a result, some breast cancers can be missed in case of only mammography screening (Leung, Huang, Chen, Lin, Wu, Lee, 2010).

Women aged 45 to 55 years were the participants of the next survey related with the mammography and MRI efficiency. These women who had a 50% risk of being the carriers of BRCA mutations were recruited from 1997 to 2003 in the Breast Screening Study Group trial. All the participants underwent the mammography and MRI annually. As a result, it was found that MRI depicted more cancers than mammography or ultrasonography. Moreover, the sensitivity of the annual MRI differed from 70% to 90% while the sensitivity of mammography varied from 30% to 60%. The study observation suggested that the cancers in women with BRCA1 carriers might grow more rapidly or that the cancers in carriers of BRCA2 could be easily detected by means of the mammography or MRI than US. Multifocal disease has not being found on either MRI or mammography imaged during the study (Gilbert, Warren, Lim, Thompson, Eeles, Evans, Leach, 2009).

The data of one more investigation has proven that the use of MRI has more potential for benefit in the area of breast cancer detection since it is possible to detect a primary tumor in a great number of women with axillary metastases by means of this modality. In other words, MRI gives the possibility to identify a very low-volume disease (Morrow, Waters, Morris, 2011). Granader et al. findings were consistent with the below mentioned survey. It was conducted on the basis of data from MEDLINE, ACP Journal Club, PubMed, SCOPUS databases. Moreover, the articles on the investigated theme were collected and assessed. The results of the study demonstrated that MRI or the combination of MRI with the mammography were able to show better sensitivity than the mammography by itself. This statement is especially true for patients at hereditary risk of breast cancer or for those who possess BRCA1/2 (Granader, Dwamena, Carlos, 2008).

The investigation of mammography, US and MRI phenotypes of inherited breast cancer was conducted by Schrading et al. According to their study, the breast density in women with a positive mammogram was not significantly different from those with negative mammogram. This suggests that the breast density is not the main reason that causes low sensitivity of mammography in patients with inherited breast cancer. However, the opposite suggestions were also reviewed. Since Asian women have dense breast, some breast cancers can be missed if screening involves only mammography (Leung et al. 2010).

On the basis of Schrading et al study results, the relatively low sensitivity of MRI in patients at high familial risk of breast cancer can be explained by the unusual features: kinetic features and non-masslike enhancement. The fibro adenoma cancer (BRCA1) was more problematic for mammography and US than it was for MRI. The survey results implied that the surveillance strategies might be related with the type of risk category. Mammography will be of limited use for carriers of BRCA1. This finding was explained by the absence of calcifications in the BRCA1-associated cancers. However, the mammography may provide the additional diagnostic information for the women with BRCA2 mutation and for those patients who are considered to be at increased risk of breast cancer (Schrading, Kuhl, 2008).

The disadvantage of close interconnection of these two modalities was demonstrated as well. The Dutch multicentre trial participants were divided into two groups. The first group received mammography and clinical breast examinations annually while the second group underwent MRI and CBE annually and mammography biannually. The study that offered MRI and mammography in combination had several shortfalls. Neither the test sensitivity nor the stage of cancer can be assessed without the data of both modalities(Saadatmand, 2012).

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