RC 402 - Screening for breast cancer
Breast cancer screening as currently practised is not a perfect test, nor is it ever likely to be. Improvements on current digital techniques are available; however, the question whether these techniques move the needle far enough in the direction of detection of biologically relevant invasive cancers with the minimization of call backs and biopsies. Furthermore, there is the question of size of cancer at detection - the average size of cancer detected is still over 1 cm which has not dramatically improved over decades. If we are to make a difference in breast cancer mortality we need a technique that can detect breast cancer when it is very small - likely well under a cm - before it has a chance to become heterogeneous and undergo clonal expansion. Resistance to treatment and development of subclones which may be different from the original tumour contribute to the mortality. There is a need to be able to differentiate those cancers requiring aggressive detection and treatment from those that do not.
1. To learn about benefits and limitations of mammography screening.
2. To become familiar with common findings, recall rates and assessment outcomes.
3. To appreciate errors.
Screening with mammography has proven to save lives. The reduction in mortality is substantial. In the Netherlands, woman who attend all biannual offered screening rounds from 50-75 years reduce their chance of dying from breast cancer before the age of 80 to 50%. The basis for this positive effect from screening with mammography is only training and auditing. The shift from analogue form to digital between 2005 and 2010 has improved these results and showed that more high-risk tumours were detected by mammography. The cost-effectiveness of screening with mammography only is acceptable. The drawbacks of screening with mammography, false positive and overdiagnosis will be discussed. So far no other modality has proven to save lives and no information is available regarding the aggressiveness of other modalities that detected breast cancers. The positive predictive value of ultrasound is substantially lower and quality control (operator dependent) is difficult. For these reasons, screening with mammography only still is the gold standard for population-based screening with an average risk.
1. To learn about the added value of US in screening and its indication.
2. To become familiar with the common level of evidence.
3. To appreciate its role in clinical practice.
The sensitivity and specificity of mammography are limited in highly fibroglandular breasts. Digital mammography provides increased sensitivity in young women and those with moderately dense breasts, and digital three-dimensional mammography (tomosynthesis) promises further improvement. For women with the densest breasts, however, radiography is unlikely to be the optimum solution. MRI, although not affected by breast density, is expensive and access is often limited. Ultrasonography is attractive for breast cancer screening because, likewise, it is not impaired by breast density, and it avoids the use of ionising radiation and the need for breast compression. Nevertheless, enthusiasm for the use of ultrasonography has been limited because its specificity has been much lower than that of mammography, but technical developments have given rise to sharper, more informative images. These improvements foster the use of ultrasound particular in those women with higher breast density. Different trials have been preformed and promising results have been reported. This talk will focus on benefits, harms, and cost-effectiveness of supplemental ultrasonography screening for women with dense breasts.
1. To learn about the role of tomosynthesis in the screening setting.
2. To become familiar with the different protocols.
3. To appreciate potential advantages of tomosynthesis in screening.
By eliminating ambiguity from superposition of normal breast parenchymal structures, digital breast tomosynthesis (DBT) holds the potential to improve cancer detection rates while at the same time reducing call-backs related to false-positive findings. The magnitude of these two effects will depend on the clinical setting. In European population-based screening programs, where recall rates are kept low, DBT will primarily increase detection rates. On the other hand, in screening practices with high recall rates such as in North America, the main effect of DBT will be to lower recall rates by improving specificity. In screening, the advantages of DBT must be weighed against the potential disadvantages of DBT such as higher costs (higher equipment and image storage costs, longer reading times) and possible increases in radiation exposure, especially if DBT is used as an adjunct to 2D mammography. Synthetic 2D views reconstructed from the DBT dataset can be used to replace 2D mammography in screening; however, the impact of this especially on the detection of microcalcifications is still unclear. Despite the very promising data from the available first DBT screening trials, which all showed a significant increase in detection rates with DBT; further studies are needed before DBT can replace 2D mammography in population-based screening programs. The key question still unanswered up to now is whether the additional cancers found by DBT are in the majority clinically relevant and contribute to a reduction in advanced-stage interval cancers.