Short Article

The Right Kind of Breast Cancer Detection

Providing conclusive breast cancer detection answers to patients can take a significant amount of time because often doctors must weigh a wide range of patient issues and risk factors. At the same time, the growth of alternative and advanced methods for breast cancer detection is presenting a more complex scenario and set of criteria to consider when selecting the most effective test for a specific patient, such as women with dense breast tissue. Below we compare conventional as well as advanced methods to help provide insights into matching the right breast cancer detection to the right patient.

Mammography reduces mortality for older women with average risk

Mammography (MG) has long been considered the most cost-effective and appropriate cancer detection method, particularly for those women with an average risk of developing the disease based on factors like family history, genetics, and tissue density.1 Clinical trials and other studies have reported MG reduced mortality related to breast cancer for women age 40 to 74, and particularly for those over the age of 50, but not for women younger than age 40.2 One study reported a mortality benefit for deaths related to breast cancer of 15 to 29 percent for women in their 40s and 50s.3

Despite those mortality benefits, medical experts note that the sensitivity and specificity of MG alone for detecting breast cancer are less than ideal when it comes to identifying lesions in women with elevated risk factors.1 However, research is demonstrating that when MG is supplemented with more aggressive approaches for detecting tumors, such as contrast-based methods, diagnostic accuracy improves in patients with a higher than average risk.1 Doctors must also factor in false positives as a concern because of time-consuming and costly follow-up tests as well as increased patient anxiety before results confirm that cancer is not present.3 

CEM delivers decisive answers fast for women with dense tissue

An advanced approach to breast cancer detection that is removing breast tissue density as a limiting factor in the interpretation of two-dimensional (2D) MG is contrast-enhanced mammography (CEM).4,5 It can be performed in less than 10 minutes using the same equipment as MG when results are inconclusive but offers a sensitivity of 100 percent, specificity of nearly 88 percent, a positive predictive value of more than 76 percent, and a 100 percent negative predictive value. i.e., the information quality physicians need for confident clinical decision making.4,5 

Just like in MG, standard craniocaudal and mediolateral oblique image views are acquired during CEM, except that the images are scanned about two minutes after the intravenous injection of a contrast agent.4,5 This is because the contrast agent will enhance any existing areas of increased and/or abnormal angiogenesis, a condition linked to the presence of breast cancer.4,5 

Clinics are adding CEM to their full breast imaging schedules with minimal disruption including reports that physicians are able to add the exam in real-time or as an appointment add-on to increase clarity.4,5 This has decreased the time-to-treatment along with patient anxiety caused by wait times for unknown results, and other issues associated with follow-up methods like access, scheduling, and/or cost are also eliminated.5

Radiation-free MRI exams recommended for younger women at high risk

According to national cancer organizations, breast magnetic resonance imaging (MRI) exams may offer many advantages over MG as well.6,7 But even despite the advantages, MRI is not recommended as a replacement for MG, but rather as an additional screening method in patients at high risk because there are cancers MRI is unable to detect that MG can.6,7 

One advantage of breast MRI is the absence of radiation.8 For this reason, it can be used to examine women at high risk for developing breast cancer under the age of 40 when breast tissue is more sensitive to radiation as well as with women over 40 who received radiation to the chest between the ages of 10 and 30.1,8 Additional advantages of MRI include 3D spatial resolution, detection of occult, multifocal/multicentric disease, and the ability to image both breasts and chest wall.1,8 Improvements include true lesion size determination whereas MG often underestimates the size of the cancer.1

Breast MRI has a sensitivity of 99 percent compared to MG at less than 68 percent.1 However, the specificity is a wide-ranging 37 to 97 percent with a much lower positive predictive value because it enhances both benign and malignant tissue.1 In other words, it is more likely to find something that is not cancer with breast MRI and end up with a false positive requiring more testing and potential biopsies.1,6 

For example, one study that examined data from more than 13,000 breast cancer survivors from five different sites who received 33,000 mammograms and more than 2,500 breast MRIs reported a detection rate nearly 11 per 1,000 exams for MRI compared to just over 8 for MG.9 However, the biopsy rate for breast MRI was more than twice (10 percent) that for MG at four percent.9

Other drawbacks associated with breast MRI include longer exam times of 45 to 90 minutes, higher costs, use of an intravenous contrast agent, and limitations for patients with metal implants or who are claustrophobic, as well as those who cannot lie prone or are too large for the equipment.1,8

Today, conclusive breast cancer detection results for women with risk factors such as dense tissue are possible, and in some cases will be in clinical use sooner than previously thought, especially when a contrast-based method such as CEM is used. While evaluating all the risk factors is more complicated, matching the right breast cancer detection exam with the right patient can have life-changing impact.

References:

  1. An overview of breast MRI. Applied Radiology https://appliedradiology.com/articles/an-overview-of-breast-mri Accessed 8/16/2019
  2. National Cancer Institute https://www.cancer.gov/types/breast/mammograms-fact-sheet  Accessed 8/16/2019
  3. Mammogram guidelines: What are they? Mayo Clinic https://www.mayoclinic.org/tests-procedures/mammogram/expert-answers/mammogram-guidelines/faq-20057759 Accessed 8/16/2019
  4. Contrast-Enhanced Mammography: A Systematic Guide to Interpretation and Reporting. AJR https://www.ajronline.org/doi/full/10.2214/AJR.17.19265  Accessed 8/16/2019
  5. The Future of Contrast-Enhanced Mammography. AJR https://www.ajronline.org/doi/full/10.2214/AJR.17.18749 Accessed 8/16/2019
  6. Breast MRI Scans. American Cancer Society https://www.cancer.org/cancer/breast-cancer/screening-tests-and-early-detection/breast-mri-scans.html Accessed 8/16/2019
  7. Breast MRI. ASCO Cancer.net https://www.cancer.net/navigating-cancer-care/diagnosing-cancer/tests-and-procedures/breast-mri Accessed 8/16/2019
  8. Breast MRI. Insideradiology https://www.insideradiology.com.au/breast-mri/ Accessed 8/16/2019
  9. A key benefit, and potential harm, of adding MRI to breast cancer screening programs. Radiology Business https://www.radiologybusiness.com/topics/quality/breast-mri-breast-cancer-mammography-rsna Accessed 8/16/2019