This Paper Was Prepared For_________ Taught By___________ Essay

Discussion 2/1

Introduction
Mammography is a tool which can substantially reduce the number of deaths from breast cancer due to early diagnostics. However, due to sensitivity and specificity issues as well as low positive predictive values the question of its feasibility as a routine screening method for certain patients remains controversial. This paper explores the issues related to mammography’s validity and reliability and associated ethical dilemmas and controversies.

Mammography as a screening and diagnostic tool

Mammography is a low-dose X-ray imaging used to obtain the pictures (images) of breast called mammogram. The mammography device uses adjustable plate on the top and X-ray or digital detector at the bottom to get detailed breast images. Mammography is used both as a routine screening tool to detect early breast cancer in asymptomatic women and as a diagnostic tool to confirm the findings in symptomatic women. It remains the main method to pick up the early stage cancers due to its availability and cost-effectiveness (NCI, 2015).

Validity and reliability

Both the US and the rest of the world evidence shows that sensitivity of mammography is relatively low and estimated between 39-95% by different sources, with average rate of 79% (HQU, 2007; CRUK, 2012; NCI, 2015). However the sensitivity rates vary widely in different age groups. The high density of breast tissue in women under 40 makes the sensitivity extremely low in this group (NCI, 2015). On the contrary, for women aged 40-49 the sensitivity reaches 75%, and for those over 50 years, 85% (HQU, 2007). It also depends on the patient’s age, menstrual cycle, tumor size and location, and hormone sensitivity (NCI, 2015). Combination of mammography with breast clinical examination or MRI increases sensitivity rates (HQU, 2012; NCI, 2015), and the sensitivity of modern digital mammography is significantly higher than of film mammography (HQU, 2010; CRUK, 2012). Specificity is approximately 80% for younger women versus 90% for women over 50 years, with some studies showing the average over 95% (HQU, 2010; CRUK, 2012). However, even with such high specificity levels, most abnormal mammograms are false-positives (NCI, 2015). Mammogram positive predictive value (PPV) is lower at the first screening than in subsequent investigations of unusual findings (CRUK, 2012). PPV of abnormal screening mammograms increases with age, and varies from 6.3% for women aged 40 to 7.8% for women aged 60 to 69 years (NCI, 2015). PPV highly depends on such variables as age, higher number of previous breast biopsies, family history of breast cancer, and use of hormon replacemeent therapy as well as on intervals between screenings and radiologist’s interpretation skills (NCI, 2015). False negative results reach about 20%, with many high-risk cancers being underdiagnozed (NCI, 2015).

Controversies and ethical dilemmas.

Conclusion
Though mammography remains a standard for early breast cancer detection, the moderate sensitivity and specificity of this diagnostic tool leave the issue of its usefulness as a routine screening in the age of 40-49 years highly controversial. High number of false positive results leading to overdiagnosis causes psychological distress and overtreatment in such patients. Meanwhile, the routine screening in the age over 50 demonstrates increasing levels of sensitivity and specificity, and can be used as a valid screening and diagnostic tool. Combination with MRI can be recommended to the patients from high-risk groups to increase the test sensitivity.

References

1. American College of Obstetricians and Gynecologists (ACOG) (2010). ACOG Statement on Revised US Preventive Services Task Force Recommendations On Breast Cancer Screening. Retrieved from:  http://www.acog.org/About-ACOG/News-Room/News-Releases/2009/ACOG-Statement-on-Revised-US-Preventive-Services-Task-Force
2. Cancer’s research UK (CRUK) (2012). Breast screening other issues. Retrieved from:  http://www.cancerresearchuk.org/cancer-info/cancerstats/types/breast/screening/Other-Issues/
3. Health Quality Ontario (HQO) (2010). Cancer screening with digital mammography for women at average risk for breast cancer, magnetic resonance imaging (MRI) for women at high risk: an evidence-based analysis. Ont Health Technol Assess Ser.,10(3),1-55.
4. Health Quality Ontario (HQO) (2007). Screening mammography for women aged 40 to 49 years at average risk for breast cancer: an evidence-based analysis.Ont Health Technol Assess Ser. ,7(1):1-32.
5. National Cancer Institute (NCI)(2015). Harms of Screening Mammography.Retrieved from: http://www.cancer.gov/cancertopics/pdq/screening/breast/healthprofessional/page8
6. U.S. Preventive Services Task Force (USPSTF) (2010). Breast Cancer Screening. Retrieved from: http://www.uspreventiveservicestaskforce.org/Page/Topic/recommendation-summary/breast-cancer-screening