Mammography

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Breast cancer screening by mammography recommended every year in women ages 50-69.

Mammography accounts for almost $8 billion in annual healthcare expenditures in the US.

Mammography screening programs are associated with reduction in breast cancer, mortality of more than 20%.

Nearly 40,000,000 women undergo routine mammogram studies in the US each year and about 43% of these exams reveal the presence of dense breasts.

In the United States many groups encourage annual screening starting at age 40, while in most other countries recommendation begins screening at age 50 and less frequent intervals of every 2-3 years.

ACS 2015 now recommends that women of average risk of breast cancer wait to reach the age of 45 to undergo annual screening mammography.

ACS recommends after age 55 mammography should go to every other year.

ACS recommends no age limit, except that patients should have screening mammography as long as life expectancy is greater than 10 years.

As compared to clinical breast exam alone mammography increased the number of diagnosed cancers by 1-3% in the 1990’s.

Stable incidence of metastatic breast cancer suggests probability of developing breast cancer is itself stable.

Screening mammography has been unable to identify at an earlier stage, before symptoms appear cancers destined to become metastatic.

No specific upper age at which mammography screening should be discontinued, and should be based on individual benefits and risks of screening in the overall context of the patients health status and estimated longevity.

The use of mammography increased to about 75% of all women in the United States in the 1990s but has decreased since that time, related to cost, limited access, and tendency for women to forgo the test after experiencing normal mammograms.

False positive mammograms result in overdiagnosis costs of about $ 4 billion/year.

In  the US approximately 11% of women receive a false positive result from a single screening.

After 10 screenings approximately one and five women in Europe, experienced at least one false positive mammogram result.

False positive results may lead to psychological distress, anxiety, and may influence the success of screening programs, suggesting false positive results represent a critical public health issue.

Studies consistently show that women with false positive results have an increased risk of developing breast cancer within 10 years of follow up, compared with women without false  positive results.

In a Swedish study women with false positive mammography, have an elevated incidence of breast, cancer, and mortality, for up to 20 years (Mao C).

As long as a woman is in good health and can benefit from the treatment of breast cancer screening with mammography should be done.

Women with an estimated life expectancy of at least 5 years should be considered for screening mammography.

Success of this technique depends on the contrast between the tumor and surrounding breast tissue, and its effectiveness is diminished when surrounding tissues have similar densities such as with non-calcified DCIS, invasive lobular carcinoma, or some  multifocal cancers.

Sensitivity of this technique is greatest in women with breast primarily comprised of fat tissue.

In a study of women over the age of 80 years of age mammography on a regular basis detected breast cancer at a lower stage and associated with a higher rate of breast cancer specifici survival (Badgwell BD).

May be less sensitive in younger women, and women with dense breast tissue and possibly in women at risk for lobular cancer.

Most calcifications found in ductal carcinoma in situ (DCIS).

Offers the possibility of reducing breast cancer mortality by 30%.

Early detection offers women ages 50-64 years the best chance for longer survival and potential cure.

Calcifications on mammography nonspecific with only 20%-35% proven to be cancer after biopsy.

Strongly recommended for women on HRT or for women with prolonged exposure of greater than 7 years on HRT.

False-negative rate for women aged 40 through 49 years is 13-15% and in women older than 50 years 6-12%.

More than 10% of screenings result in a recommendation for additional imaging at the time of mammography and only 4.4 % of such patients will have a diagnosis of breast cancer within 1 year.

False positive results increase annual U.S. medical costs by approximately $200 million.

Patients with architectural distortion on mammography are more likely to have positive margins than patients with masses or calcifications.

Tumors presenting as architectural distortions on mammography are significantly larger than tumors presenting with other mammographic abnormalities.

False-positive rate 5-6% dependent upon age.

In women 50 years old or older a 22% reduction in breast cancer mortality has been found at 14 years of observation.

In women 40-49 years old the risk reduction in breast cancer mortality is 15% at 14 years of observation.

In women aged 50-59 years risk reduction in breast cancer mortality is 14% at 14 years of observation.

In women aged 60-69 years risk reduction in breast cancer mortality is 32% at 14 years of observation.

Because of the variation in prevalence it requires screening of 1904 women in their 40s to prevent 1 breast cancer death, and 1338 women in their 50s, and 337 women in their 60s.

Decrease in mortality from studies attributable to decreased in the size distribution of cancers detected on screening mammography.

Approximately 62% of women in their 30’s, 56% of women in their 40’s, 37% of women in their 50’s, and 27% of women in their 60’s have at least 50% parenchymal densities evident on mammography.

Radiology technicians who perform mammography and physicists that oversee technical aspects of mammography must meet requirements for training, continued experience and continuing education.

Every three years mammography facilities are required to submit screening mammograms of a patient with dense breasts and a patient with fatty breasts for each unit to experts to evaluate for image quality, including positioning, compression, sharpness and labeling.

False positive results occur in up to 10% of screening mammographic examinations.

As breast density increases the sensitivity and specificity of mammography decreases.

Breast density is variable and affected by exogenous and endogenous hormones and higher rates of mammography recall exist among women on hormone treatment.

High breast density is associated with larger tumor size, positive lymph nodes, and advanced stage breast cancer.

The risk of advanced stage breast cancer is increased further in women with dense breasts who use postmenopausal hormone therapy.

Brief stoppage of hormone therapy before mammography results in small changes in breast density but does not affect recall rates (Buist D).

Biennial screening mammography for most women age 40-49 and 50-74 years, even those with high breast density or receiving combination hormone therapy have similar risk of presenting with advanced stage disease as annual screening mammography (Breast Cancer Surveillance Consortium).

Between 20-30% of visible lesions are missed and studies indicate that detection rates increases with multiple radiologist reviews.

In a study of 108 radiologists a range of 40% in the sensitivity of detecting breast cancer existed (Beam CA).

Cumulative risk of a false positive result after undergoing 10 mammographic screenings is 49%.

Calcifications in breast arteries indicate an increased risk for cardiovascular disease.

Mammography during pregnancy poses little risk to the fetus and this technique is considered safe with a radiation dose to the fetus from standard bilateral mammography using abdominal shielding estimated to be 0.004 Gy of radiation, but does well below the threshold for malformation in the fetus of 0.05 gray of radiation (Greskovich JF).

Mammography early in pregnancy is associated with lower exposure to the fetus.

In general, mammography density of breast increases with pregnancy induced breast changes, and this decreases the sensitivity for detecting the underlying masses and malignancy.

Rate of abnormal mammography reading is 2-4% higher in the U.S. compared to other countries.

Despite a higher recall rate in the U.S., the detection rate per 1000 exams is similar to other countries, but the detected lesions are less advanced.

A higher rate of abnormal mammogram readings increases the false positive rate much faster than the detection rate.

As many as 50% of women who undergo annual screening mammograms will have an abnormal test after 10 years.

In a Norwegian observational screening mammogram program a 10% reduction in breast cancer mortality was achieved among women between the ages of 50 and 69 years (Kalager M), this is a much smaller benefit than the reduction in mortality a 15-23% estimated by the US Preventive Services Task Force (Manelblatt JS).

It is estimated that 2500 women would need to be screened over a 10 year period to avoid 1 death from breast cancer (Kalager M).

Mammography in the United States of 1000 women at least one false positive result would be expected (Elmore JG).

Mammography can result in somewhere between a five and 15 women will be needlessly treated for condition that was never going to bother them, with all its associated difficulties (Zackrisson S et al, Jorgensen KJ et al).

In patients with BRCA 1 or BRCA 2 mutation sensitivity of the study is poor, ranging from 36-55% (Gui).

Patients with BRAC 1 and BRAC 2 mutations have a relatively rapid doubling time, and interval cancers diagnosed between yearly mammography screenings have been noted in approximately 50% of these women.

Interval breast cancers refer to in situ or invasive cancers detected following a negative mammographic screening examination and before the date of the next recommended screening mammogram.

Interval breast cancers are divided into a) true interval and b) missed interval cancers.

True interval breast cancers referred to a review of the screening mammogram before diagnosis that is truly negative.

Missed Interval breast cancer is referred to the process whereby the screening mammogram before diagnosis reveals a mammogram abnormality that was initially falsely negative.

True interval breast cancers are associated with more adverse prognostic factors compared with screen detected cases.

Interval cancers are more likely to be greater than 1 cm in size, have lymphovascular invasion, have the grade 3 features, have lymph node involvement, exhibit triple negative features and patients with breast cancer screening detected cases (Rayson D et al).

Patients with BRCA mutation carriers can present with relatively benign radiographic features contributing to false negative interpretations.

By the year 2000 70% of women in their 40’s have had a screening mammography in the previous two years.

Only 1-2 lives would be extended per 1000 women 40-50 years of age who are screened annually for 10 years.

Mammography is indicated in the evaluation of the patient with a known palpable breast cancer because it allows for the whole breast to be viewed, and that cannot be done by sonography.

Mammography in the presence of a breast cancer may provide better understanding of the 3-dimensional location of the cancer within the breast.

Mammography can detect small calcifications that may indicate malignancy extending beyond the site of a cancer.

Digital mammography is better in protecting breast cancer in women with dense breast tissue, and in women under the age of 50 years.

The estimated cumulative risk of death from breast cancer due to radiation from mammography screening is 1 to 10 per hundred thousand women, dependent on age and frequency and duration of screening.

Radiation induced breast cancer rate is at least smaller by a factor of 100 in estimates of death from breast cancer prevented by mammography screening.

USPSTF recommends initiation of breast cancer screening at age 50 years, as the average age of onset of menopause in the US is 51 years and breast density decreases after menopause.

Breast tissue density in younger women is increased and increases the likelihood of false negative findings because it is more difficult to identify small lesions in dense breasts.

Increased breast density is in independent risk factor for the development of breast cancer.

Younger women have more false positive results.