BREAST CANCER: SCREENING AND DIAGNOSTIC METHODS
Mar 26, 2020
Breast cancer affects a large number of women worldwide. Its early detection can decrease the mortality rates and provide a better quality of life. Although mammography remains the first choice method for breast cancer detection, several Softwares that facilitate the analysis of mammograms and more advance techniques with increased sensitivity have entered the clinical market. Lastly, genetic and biomarker testings are also useful tools in the fight against breast cancer.
Breast cancer refers to malignant tumors due to the uncontrollable growth of breast cells. Even though almost all cases of breast cancer occur to women, men can develop breast cancer as well. (1) Besides skin cancer, breast cancer is the most commonly diagnosed type of cancer and it is estimated that approximately 1 out of 8 women in the US will develop it at some point in their lives. (2) The most prominent risk factors for developing breast cancer are sex (women) and age. The majority of cases occur in women over 50 years old, but it is also possible for younger women to develop breast cancer. (2) Early detection of breast cancer can decrease mortality rates.
The diagnosis of breast cancer relies on different diagnostic methods. The gold standard for breast cancer detection includes physical exams and screening tests. When the cancer cells start to multiply, they can form a tumor that can be seen on the x-rays or felt as a lump. (1) These lumps can be found by doctors or health professionals who will carefully examine the breast manually. (3) Moreover, screening tests, such as mammography, can detect breast cancer early. For that reason, healthy women should have their breast examined regularly. (4) Mammography has a high specificity mostly in postmenopausal women whereas it is not as sensitive to premenopausal women partly due to denser breast tissues. (5) It is recommended that women at average risk should get an annual mammogram starting at age 40 whereas women with a higher risk of breast cancer should get screened even earlier. (4)
One important factor that can limit mammography is breast density. However, when it is supplemented with other screening methods like ultrasound, CT scan, molecular breast imaging, and MRIs, the sensitivity for cancer detection can be up to 95%. (5) For example, MRI can detect early-stage breast cancer more effectively than traditional screening methods, especially if combined with ultrasound. MRI is more sensitive than mammography - in fact, it is the most sensitive imaging method for breast cancer - but it can pick up abnormalities that are not cancer (many false-positive results). For that reason, it is usually used in women at high risk for breast cancer (BRCA1 and BRCA2 positive) for early-stage detection. Another available technique is the automated breast ultrasound system. When this method is used together with mammography in women with dense breasts, it can increase cancer detection by up to 38%. (6) A new screening test with promising results is digital tomosynthesis or 3D mammograph, which combines multiple breast X-rays to create a three-dimensional picture of the breast. This allows easier detection of breast cancers with a more comfortable procedure even in women with dense breast tissue. (4)
Genetic and Biomarker tests:
Genetic tests are also useful in breast cancer detection. A small percentage of breast cancers (5-10%) can be linked to mutations of hereditary genes. The most common genes of this category are the BRCA1 and BRCA2 genes. According to research, women with BRCA mutations are at higher risk not only to develop breast cancer but also to do so at a younger age. (2) There are many tests in the market that screen for gene mutations. These tests are usually performed in a blood sample and it can take up to several weeks to receive the results. Some of them are more specific to detect BRCA1 and BRCA2 mutations, whereas others can test for mutations in a panel of genes and can be used to predict the predisposition of a patient to different types of hereditary cancer (breast, ovarian, colon, prostate, melanoma). (7-12)
Biomarker tests are also useful in evaluating the probability of a woman developing cancer or in detecting early-stage breast cancer. A biomarker is a substance found in blood, urine or other fluids. In the case of cancer, dysregulation of biomarkers, or other substances made by the tumor or by the human body as a response to the tumor (cancer markers) can be found. (13) Biomarker testing helps to obtain more information about the cancer type and to choose the best treatment option. The most commonly tested biomarkers in breast cancer are estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2). (13) Other tests that measure the number of circulating tumor cells and the levels of serum microRNAs are in clinical research and might be an additional tool for cancer detection. (14) (15)
Software and AI:
In the latest years, cancer detection has been supplemented by new software and AI-powered screening platforms that can provide a comprehensive, objective and automated assessment of images from mammography or tomosynthesis exams. The combination of novel technological methods with the pre-existing imaging processes can increase the accuracy of malignancy detection and reduce the false positives and negatives. (16-21)
Lastly, various initiatives aim to improve the quality of cancer screening and make examination procedures accessible to everyone. In addition, several studies and programs try to personalize cancer screening based on risk assessment. According to these programs, the breast screening strategy should be adapted using personalized risk estimation. In this way, breast cancer can be detected earlier. (22-24)
Breast cancer is one of the most severe types of cancer and it affects many women worldwide. Its early detection can be the key to a faster recovery and a decrease in mortality rates. Even though mammography is still the method of choice for breast cancer screening, its combination with software or other imaging techniques has increased the accuracy and specificity of breast cancer detection. However, there is still a need for even more accurate, easily accessible and fast techniques for cancer diagnosis.
1. What is Breast Cancer. American Cancer Society. https://www.cancer.org/cancer/breast-cancer/about/what-is-breast-cancer.html
2. US Breast Cancer Statistics. BreastCancerOrg. https://www.breastcancer.org/symptoms/understand_bc/statistics
3. Breast Physical Exam. BreastCancerOrg. https://www.breastcancer.org/symptoms/testing/types/physical_exam
4. Breast Cancer Tests: Screening, Diagnosis, and Monitoring. BreastcancerOrg. https://www.breastcancer.org/symptoms/testing/types
5. Effectiveness of Breast Cancer Screening: Systematic Review and Meta-analysis to Update the 2009 U.S. Preventive Services Task Force Recommendation. Nelson, Heidi D., et al. s.l. : Annals of Internal Medicine , 2016.
7. RocheFoundation. https://www.rochefoundationmedicine.com/cancertesting.html
8. ThermoFisher Scientific. https://www.oncomine.com/assays
9. Genekor. https://www.genekor.com/en/heredigene/
10. Invitae. https://www.invitae.com/en/physician/tests/01101/
12. Lucence. https://www.lucence.com/cancer-screening/#lumifocus
15. Division of Molecular and Cellular Medicine (Ochiya Group). National Cancer Center Japan. https://www.ncc.go.jp/en/publication_report/2016/nccri/nccri15.html
17. CureMetrix. https://curemetrix.com
18. Kheiron Medical Technologies. https://www.kheironmed.com
19. HERA-MI. https://www.hera-mi.com/en/about-us/
20. ContextVision. https://www.contextvision.com/products/mammography/
21. Mammoscreen by Therapixel. https://www.mammoscreen.com
22. My PeBS. https://mypebs.eu/the-project/
23. Cenla Medication Access Program. https://www.cmaprx.org/Home.aspx
24. EU-TOPIA. https://eu-topia.org/about-eu-topia/objectives/
25. https://www.nationalbreastcancer.org/breast-cancer-facts (banner image credit)