Introduction
Screening women for breast cancer has been a classical domain of conventional imaging. X-ray-based mammography (XM) herein represents the main diagnostic pillar as it is considered affordable, accompanied by a reasonable sensitivity and specificity level in order to cope with the number of patients at aim [
1‐
3].
Recently, cost-effectiveness analyses of XM for breast cancer screening have gained further interest [
4‐
6].
MR-mammography (MRM) today is accepted to be a highly accurate imaging technique in the detection of breast cancer [
7‐
11].
However, it has so far not been recommended by the major breast societies as a standard technique for any other indication than patients at high risk of developing breast cancer and as an occasional problem solver [
12,
13].
Reasons may have been some studies suggesting MRM to be generally unspecific and therefore not cost-effective, considering the higher “per examination” cost [
14].
However, some publications in recent years indicated a possible new role for MRM in patients with BI-RADS 3 or 4 findings as a problem solver [
15] or in patients at intermediate risk due to dense breast tissue [
9,
16].
To our knowledge, the first study examining conventionally difficultly assessable patients at intermediate risk due to dense breasts with MRM, unaccompanied by conventional imaging as a solitary imaging tool, was the TK-Study [
9].
The study was able to demonstrate sensitivity levels for MRM of 100%, as well as specificity levels of 97% in approximately 1200 patients, either biopsied or followed-up as the gold standard of reference.
In line with the results of several studies on MRM in high-risk patient samples, the study gave arguments against a commonly spread presumption that a lack of specificity should be a reason against the use of MRM beyond common indications [
7,
8,
17].
Another argument mentioned against a possible role of MRM in a broader set of indications has always been its cost-effectiveness compared to conventional imaging, which—as of today—is yet to be verified.
The determination of the cost-effectiveness of MRM in women at intermediate risk due to dense breasts so far was difficult, as data on the accuracy of MRM was mainly available in high-risk patient collectives.
Additionally, data suggested that reader experience may have a considerable impact on accuracy and therefore on the cost-effectiveness of MRM. Experience levels in MRM are still reported to be heterogeneous, also as a result of limited utilization of MRM [
9].
Therefore, concerns regarding the economic feasibility of an extension of the current set of indications for MRM remain popular [
18].
The aim of this study is to assess the economic impact of MRM, based on the data from our previously published, prospective TK-Study collective, examining patients with dense breasts in a stand-alone setting outside the current list of indications.
Discussion
The TK-Study in its two parts, to our knowledge, was the first study to assess both the diagnostic accuracy and the economic significance of MRM in patients at intermediate risk of breast cancer due to their dense breast tissue.
In the first part of the study [
9], the authors could find evidence for a high diagnostic accuracy of MRM in patients at intermediate risk due to dense breasts as a solitary imaging tool, i.e., without the help of conventional imaging, in line with quite recent and well-published data [
28].
This scientific sequel about the economic significance illustrates that MRM may well be considered cost-effective in this novel patient cohort, suggesting an adaption of international guidelines, currently indicating MRM in high-risk patients only, along with a small role as problem solver [
12,
13,
29] in special cases.
The results of this publication indicate clinical impact, as they suggest utilizing MRM in patients with dense breasts, if necessary, as a solitary imaging technique. MRM may be the method of choice not only in terms of accuracy in the detection of small tumors [
30,
31] but also in terms of cost-effectiveness in patients with dense breasts, i.e., in patients, where conventional imaging is facing problems in accuracy due to breast density.
As this economic analysis is based on the prospective data of the TK-Study, the results have to be interpreted in the context of its input parameters: Due to its non-comparative nature, this study investigated the overall costs of MRM, uncompared to any other diagnostic modality, claiming cost-effectiveness only within the range of the WTP.
In other words, within the limits of the price range, most international healthcare systems are willing to pay for an additional QALY, and MRM in dense breasts in a setting unaccompanied by conventional imaging may be considered well within the affordable range of the broad spectrum of the WTP. This is supported by the results for false negative patients in the study: Patients receiving a false negative diagnosis are associated with high upstream costs in therapy as well as lowered quality of life, preventable by the high sensitivity of MRM.
In terms of diagnostic accuracy, most recent and high-ranking published data [
28,
32] comparing conventional breast imaging and MRM is in line with our results. Thus, accuracy as well as its economic interpretation in this publication may be considered consistent.
Literature describes economic aspects of XM and DBT in the context of screening programs [
33,
34]. First results on the economic implications of MRM have also been published [
35]: Ahern et al [
27] investigated the cost-effectiveness of MRM in the context of high-risk patients reporting ICER values consistently below the WTP threshold of $100,000/QALY, supporting our results. Ahern et al [
27] did apply conservative results for MRM for their cost-effectiveness analysis, assuming a relatively low specificity for MRM, yet still confirming its cost-effectiveness.
Our analysis provides novel impact as it was conducted within a completely new patient indication (intermediate risk due to dense breasts) and was based on prospectively generated data.
Literature on the cost-effectiveness of MRM is based on its majority on conservative results of diagnostic performance and may need re-evaluation in the light of recently published literature.
The modeling performed in this study has to be interpreted in the context of its input parameters: First, the underlying hypothesis in this patient collective is that the diagnosis is achieved in early stages of the disease (Tis or T1) in the vast majority of cases. This assumption is in line with the published literature [
7,
8,
28] and leads to the further premise that a M1 stage should be very uncommon in these patients. These results are reflected in the Markov modeling presented above.
From the sensitivity analyses, certain conclusions can be drawn: First, the pre-test probability of malignancy has the most notable impact on overall costs. This is due to the fact that the impact of potentially necessary therapy on costs (opportunity costs) is vastly outnumbering the impact of diagnostic costs—even assuming
costly examinations of MRM. Furthermore, a loss in sensitivity and specificity is associated with a significant increase in overall costs (Fig.
3a) due to an increased number of false positive and false negative patients. Therefore, a head-to-head comparison with other modalities would be of high relevance in future investigations. Likewise, a loss in diagnostic accuracy was associated with quality-of-life losses. The results point at the fact that an additional investment in sensitive diagnostic modalities such as MRM may be well justified, as they result in better outcomes and lower resulting therapeutic costs. However, the results of our analysis also show a certain importance of a high level of experience of MRM readers, given that a lower accuracy is associated with losses of quality of life (Fig.
3b). This is important, given that a prerequisite for the high accuracy of MRM in the TK-Study was reader experience.
In conclusion, our results suggest MRM to be a cost-effective as well as accurate diagnostic option in patients at intermediate risk of breast cancer due to dense breasts. Further studies examining the cost-effectiveness of MRM in women of average risk should be a matter of future research, also investigating the cost-effectiveness of other imaging techniques.
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