Breast Cancer Screening Explained | Steps for Early Detection

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Breast Cancer screening

Mammography is being used for breast cancer screening since 1980’s. In 1990s, a decrease in breast cancer mortality of 2.1% was reported by the American Cancer Society. In the 15 years from 1983 to 1998, the rate of discovery of stage I breast cancer more than doubled and that of in situ carcinoma more than tripled while the incidence of stage IV disease at diagnosis fell by almost one half.

ACS recommendations for breast cancer screening:

  • Women age 40 and older should have a mammogram every year
  • Women in their 20s and 30s should have a clinical breast exam (CBE) preferably every 3 years. Starting at age 40, women should have a CBE every year.
  • Breast self-exam (BSE) is an option for women starting in their 20s.
  • Women who are at high risk for breast cancer should get an MRI and a mammogram every year.

MAMMOGRAPHY

Sensitivity of mammography ranges from 53% to 92% in western countries, being low in pre-menopausal women (from 44% to 76 % in women <50*). Specificity ranges from 82% to 98% in western countries.

It has two views, Craniocaudal (CC) and Mediolateral Oblique (MLO) to characterize the type and location of breast lump. Breast compression is done between the plates which increases image contrast, decreases radiation dose, reduces motion, and minimizes superimposition of tissues. Pain and discomfort may be addressed by soft radiolucent breast cushion, premedication with oral analgesics and topical lignocaine.

It can detect cancer 1.5-4.0 years before it is clinically evident. Mean glandular dose is 0.1-0.2 rads (1-2 mGy) per exposure, and effective rose received is around the same as that from normal background radiation for 3 months.

BIRADS Scoring on Mammography

Category 0: Additional imaging evaluation and/or comparison to prior mammograms is needed.
Category 1: Negative
Category 2: Benign (non-cancerous) finding
Category 3: Probably benign finding – Follow-up in a short time frame is suggested
Category 4: Suspicious abnormality – Biopsy should be considered
Category 5: Highly suggestive of malignancy – Appropriate action should be taken
Category 6: Known biopsy-proven malignancy – Appropriate action should be taken

Film screen Vs. Digital Mammography

According to Digital Mammographic Imaging Screening Trial (DMIST) and Oslo II study, overall diagnostic accuracy was similar but digital was more accurate for premenopausal, perimenopausal and women with dense breasts.

Digital mammography, when available, may offer a small screening advantage in women younger than 50 years old.

Abnormalities on mammography

  • The most specific mammographic feature of malignancy is a spiculated focal mass. Positive Predictive Value of mass with a spiculated margin is 81%  and with irregular shape is 73%.
  • The density of a non-calcified mass. 70% of masses with high density were malignant, and 22% with low density were malignant.
  • Clustered microcalcifications are seen in approximately 60% of cancers detected mammographically.
  • Linear branching microcalcifications have a higher predictive value for malignancy than do granular microcalcifications, especially for high grade DCIS.
  •  However, breast cancers, including DCIS, more often present with the granular type of calcifications.

Breast density

All reports have a statement regarding the breast density. Most radiologists use the four categories described in the BI-RADS atlas, based on the proportion of glandular (radiodense) tissue with respect to fatty (radiolucent) tissue. The four main categories are:

    • Predominantly fatty (0 to 25 percent dense)
    • Scattered fibroglandular densities (25 to 50 percent dense)
    • Heterogeneously dense (51 to 75 percent dense), and
    • Dense (greater than 75 percent)

Related articles:

  1. 28 Inspirational and Motivational Breast Cancer Survivor Stories.
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Clinical Breast Examination (CBE)

The sensitivity of CBE is considerably less than mammography average of 54%. The American Cancer Society states that its continuing recommendation to perform CBE is based on lack of conclusive evidence against it and the opportunity to use the examination as a time to discuss early breast cancer detection and other breast cancer issues.

Sensitivity ranges from 40% to 70% in western countries and specificity ranges from 85% to 95%. Advantage of CBE over other techniques are it’s low cost and performable by non medical staff.

Recommendations for CBE

  • The American Cancer Society recommends clinical breast examination every three years from age 20 to 39, and annually thereafter
  • The American College of Obstetricians and Gynecologists recommends clinical breast examination every one to three years from age 20 to 39, and annually thereafter
  • The US Preventive Services Task Force concludes that evidence is insufficient to assess additional benefits of clinical breast examination beyond mammography
  • The World Health Organization does not recommend clinical breast examination

BREAST MRI

American Cancer Society indications for breast MRI-

    • Known BRCA mutation carriers
    • First degree relatives of known BRCA mutation carriers
    • Women with an approximate lifetime risk of breast cancer from 20 to over 25 percent
    • Had radiation therapy to the chest when they were between the ages of 10 and 30 years
    • Have Li-Fraumeni syndrome, Cowden syndrome, or Bannayan-Riley-Ruvalcaba syndrome, or have first-degree relatives with one of these syndromes.

Annual MRI recommended based on evidence-

  • With BRCA mutated women
  • First degree relatives of BRCA mutated women
  • Whole life risk of breast cancer about 20-25%

Annual MRI based on expert opinion-

  • Women who received radiation to chest at the ages of 10-30
  • Li-Fraumeni syndrome patients and their first degree relatives

Insufficient evidence to recommend MRI

  • Lifetime breast cancer risk 15%to 20%
  • Lobular carcinoma in situ
  • Atypical hyperplasia(lobular or ductal)
  • Extremely or heterogeneously dense breasts on mammogram
  • Personal history of breast cancer, including ductal carcinoma in situ

New Methods for Breast Cancer Screening

Positron Emission Mammography (PEM)

It has a sensitivity 86 to 91% and specificity 91 to 93%. PEM does not reliably detect low grade malignancies

Breast Specific Gamma Imaging (BSGI)

It uses gamma cameras with 2 to 3 mm in-plane resolution in a mammographic configuration to provide images of the breast. It is based on the observation that breast cancers accumulate technetium-99m sestamibi in intracellular mitochondria. BSGI demonstrated equal sensitivity and greater specificity than MRI for the detection of breast cancer

Breast Tomosynthesis

Breast tomosynthesis (“3-D mammography”) has been approved by the US Food and Drug Administration for routine clinical use. It is a modification of digital mammography and uses a moving X-ray source and digital detector. A three dimensional volume of data is acquired and reconstructed using computer algorithms to generate thin sections of images.

In the screening setting, this helps to decrease recall rates by delineating true lesions from spurious lesions caused by overlapping structures seen on routine mammography. In the diagnostic setting, tomosynthesis improves lesion characterization, thereby decreasing the need for biopsy, leading to fewer false positive biopsies and higher rates of cancer detection.

 

Hope this article would have made you understand better about breast cancer screening and newer techniques for it. We recommend every one to go for it so that you can be diagnosed early. Early diagnosis is quite important to combat the disease.

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