Prevention, Screening and Health Maintenance
Family Medicine Clerkship
to home page
- Evidence & Cases
- For early detection of breast cancer
- Sensitivity of the procedure
- Specificity of the procedure
- Yearly for women over the age of 50
- For high risk patients
- Family history of breast cancer - Cancer in first
degree relative (mother, sister, daughter)
- Prior cancer breast
- Survival advantage of early detection
- Annual cost for population screening
- Number of potential subjects
- Cost per procedure
- Morbidity and harm to patients by investigations with
- Number of people benefited versus number harmed
How does mammogram differ with age?
In young women the breast is often extremely dense.
Glandular tissue and cancer are dense (white) in a
mammogram. Hence it is difficult to distinguish cancer from
normal dense glandular tissue in young women.
As women age, there is fatty infiltration of the breast
associated with atrophy of glandular tissue. Fat is lucent
(dark) in mammogram.
At what age should you start the screening mammography
for detection of breast cancer? How frequently it should be
Various recommendations are made by different
organizations. The generally accepted recommendation is a
mammogram each year starting at age 40. This is recommended
by the American Cancer Society and the American College of
Radiology in addition to many other organizations.
What is the incidence of breast cancer corrected for
- Under 20: rare
- Under 30: less than 2% of total cases
- Risk gradually increases after age 40
- Incidence of 300 cases per 100,000 in 8th decade
After which age does the risk of developing breast
cancer steadily increase in women?
After the age of 40, a woman's risk of developing breast
cancer steadily increases.
Who is at high risk for cancer breast? What risk factors
are associated with an increased chance of developing breast
Risk factors for breast cancer include:
- Gender: less than 1% of incidence occurs in males
- Age: risk increases in women after age 40
- History of cancer in one breast: risk increases 3-4
- Family history of breast cancer: 2-3 fold increase
risk if first degree relatives had breast cancer
- Non invasive carcinoma (ductal or lobular carcinoma in
- Early menarche
- Late menopause
- Late first full-term pregnancy
- Low dose radiation
- In Japan there is higher risk for breast cancer in
surviving women exposed to radiation from the atomic bomb
(only if they were exposed to high doses).
Estimate the accuracy (sensitivity and specificity) of
mammography as a screening test.
The sensitivity and specificity values are for women aged
- Sensitivity (the ability to detect disease, when
disease is present) is 75-94%.
- Sensitivity is lower among women who are less than 50
years old, have denser breasts, or are taking hormone
- Specificity (the likelihood that a mammogram will
correctly indicate that cancer is not present) is 83-98%.
- Specificity is increased with shorter screening
intervals and availability of prior mammograms.
What is the false positive rate of mammography?
Given a specificity of 83-98%, false positives occur
2-17% of the time.
What conditions give rise to false positive suspicion
for cancer breast?
Several benign breast conditions can produce a spiculated
density, which may be indistinguishable on mammography from
Spiculated mass density has been encountered in:
- Post-biopsy scarring
- Traumatic fat necrosis
- Breast abscess
- Sclerosing adenosis
- Radial scar
Also, it may be difficult to distinguish benign from
A 25 y/o woman who has a strong family history of breast
cancer comes to your office inquiring about screening
mammography at her age. What would you tell her?
A. Screening mammograms should be done once a year.
B. Screening mammograms should be done once every two years.
C. Screening mammograms are not recommended at this age.
- A screening mammogram can be conducted starting ten
years before the age of the mother's breast cancer, but
not earlier than 25 y/o.
- Screening for detection of early cancer is not
indicated for women below 40 years of age.
- The incidence of cancer is extremely low.
- The breast tissue is dense and recognition of cancer
is difficult with mammography.
- Sensitivity is lower among women who are younger than
50 (51 percent to 83 percent) and older than 70. Such
values are also lower in women having denser breasts or
women on hormone replacement therapy.
Let us now evaluate the evidence and controversy with
regards to screening mammography.
What are some potential disadvantages for screening
- Low specificity
- Cumulative risk of a false-positive result after 10
mammograms is roughly 49%.
- 80-90% of abnormal screening
mammograms or CBEs are false positives.
- False positive results can lead to undue stress,
discomfort and additional medical expenses.
- Concern for potential over diagnosis of DCIS
- Some studies show that DCIS is being diagnosed more
often now. Consequently, some patients may be undergoing
major procedures such as masectomy or lumpectomy and
radiation for lesions that might not require such
- Radiation induced breast cancer
- Estimates of up to 8 potential deaths in a
population of 100,000 women screened for 10 years
starting at age 40 have been cited ( National Academy of
Sciences). However, this is low compared to the number
of screening carcinomas found in 100,000 women.
What potential harms can occur from screening for breast
cancer with mammography?
- The large majority of abnormal screening mammograms
- These may require invasive follow-up procedures such
as unnecessary breast biopsies to resolve diagnosis, which
can result in anxiety, inconvenience and additional
Is there a potential risk for radiation-induced breast
cancer in women who receive annual mammograms?
- The risk estimate provided by the Biological Effects
of Ionizing Radiation report estimated that annual
mammography of 100,000 women for 10 consecutive years
beginning at age 40 would result in up to 8
radiation-induced breast cancer deaths.
- This risk is negligible compared to the benefits from
- The probability of developing breast cancer between
the ages of 40-49 is 1.5%; thus screening mammography
would detect 1,500 cases of breast cancer in this age
What factors contribute to the annual cost of performing
screening mammograms for women as indicated?
- Number of women over the age of 40
- Average cost for screening mammogram
- Annual cost
Screening mammography certainly detects early cancer.
What evidence do we have to show that screening mammography
and early detection of cancer prolongs life? What is the
survival advantage of early detection of breast cancer?
- Widespread use of mammography, alone or with a CBE
performed by a trained health-care provider, can reduce
overall mortality from breast cancer.
- Since the 1970s, scientific studies have demonstrated
that regular screening mammograms among women aged 50-69
years, can reduce mortality from breast cancer by 30%.
- Evidence is not as conclusive for women aged 40-49
years and > 70 years.
Screening mammogram reveals a suspicious lesion for
cancer in left breast. No mass is palpable. How would you
- Core biopsy with stereotactic or ultrasound guidance
(preferable method); or
- Radiologist performs needle localization procedure:
- Breast is compressed with a holder that has
coordinates on the sides, and mammogram is obtained.
- A thin needle is placed in the lesion through
- A blue dye is injected at the site.
- A thin hooked wire is passed to the lesion where it
- The needle is withdrawn leaving the wire in place.
- Surgeon removes the tissue around the wire tip.
- The biopsy specimen is x-rayed to make sure that the
suspicious lesion was removed.
A 35 year woman with a strong family history of breast
cancer comes to the clinic inquiring about screening. She
has no other risk factors other than family history. What
would you tell this patient regarding the current
recommendations for breast cancer screening?
- There is no need for mammography at this time.
- Instruct the patient to do self-exams.
- It is recommended that self breast exams are done
once a month in the shower; however, the USPSTF
concludes that there is not sufficient evidence to
support or oppose this teaching.
Discussion of current recommendations:
- Whether the patient is high risk or not, current
recommendation is for women to have screening mammography,
with or without CBE, every year starting at age 40 (USPSTF).
- There is insufficient evidence to recommend for or
against CBE alone for diagnosing breast cancer (USPSTF).
- There is insufficient evidence to recommend for or
against teaching or performing routine self breast exam.
What are the current recommendations?
- Mammography every year (annually) starting age 40
CHIEF COMPLAINT: “I want a mammogram.”
A 40 year old female presents to clinic asking for a
mammogram. She is a healthy, active woman with a medical
history significant only for hypothyroidism and
cholecystectomy at age 35. She is a homemaker and mother of
2 children. She has never smoked cigarettes, and drinks one
glass of wine with dinner each night. She states that her
mother died of breast cancer at age 60, and a previous
family doctor had advised her to start screening for breast
cancer with mammograms at age 40. The patient's
obstetric/gynecologic history includes the following
information: menarche age 12, menses occurs regularly every
28 days and lasts for 5 days. She is gravida 2, para 2.
PHYSICAL EXAM: The breasts are examined with the patient
in sitting and supine positions. The breasts are large,
round and symmetrical. The contour of each is smooth with no
evidence of dimpling, retraction or edema. The nipples and
areola are symmetrical, pink-tan and show no eczema or
inversion. Palpation of both breasts and axilla reveals no
Answer: This patient should have a screening mammogram