Breast cancer screening
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Breast_cancer_screening".

Breast cancer screening refers to checking ("screening") for potential breast cancer before any symptoms appear, in the hopes of detecting any existing cancer early enough in its development that effective treatment can be given.

Screening can be done in a variety of ways. The most common form of screening is a self breast exam, in which the patient checks their own breasts monthly for any abnormalities. Clinical breast exams, in which a health-care provider checks for abnormalities in the patient's breasts, are recommended annually. Abnormal findings via these screenings are investigated with diagnostic tools such as mammography, ultrasound, or magnetic resonance imaging. X-ray mammography, which is most common, uses x-rays to scan breast tissue to detect cancers, which appear distinct from the surrounding tissue; this is generally in addition to the clinical exam beginning at age 40. Additionally, genetic testing for the BRCA1 and BRCA2 genes, which are tied to increased levels of breast cancer, is possible; this is generally only recommended for women with a particularly high rate of family breast cancer or a known cancer pathology.

Breast self-exam

Main article: Breast self-examination

Breast self-examination is most effective conducted several days after the completion of the period, or if menapausal at the same day of the month each month. A self exam benefits from the patient's familarity with their body. This recognizes that normal for one patient is not necessarily normal for another patient. Patients assess if breasts are their usual size, shape, color, without visible distortion, swelling, dimpling, puckering, or bulging of the skin and without discharge from the nipples.

Breast self-examination is effective for detecting breast cancer at an earlier stage. A large clinical trial in China, reported in the Journal of the National Cancer Institute first in 1997 and updated in 2002, 132,979 female Chinese factory workers were taught by nurses at their factories to perform monthly breast self-exam, while 133,085 other workers were not taught self-exam. The women taught self-exam tended to detect more breast nodules than those in the control group. The women taught breast self-exam were mostly likely to detect benign or early stage breast disease. ¹ An editorial in the Journal of the National Cancer Institute reported in 2002, "Routinely Teaching Breast Self-Examination is Dead. What Does This Mean?"²

X-ray mammography

Main article: mammography

Mammography is still the modality of choice for screening women for early detection of breast cancer, since it is relatively fast, reasonably accurate, and widely available in developed countries. Breast cancers detected by mammography are usually much smaller (earlier stage) than those detected by patients or doctors as a breast lump.^{citation needed} Mammography has been estimated to reduce breast cancer-related mortality by 20-30%.³

Routine mammography of women 40 or older is recommended by the U.S. National Cancer Institute ⁴ and as a clinical practice guideline by the US Preventive Services Task Force ⁵ as a screening method to diagnose early breast cancer and has demonstrated a protective effect in multiple clinical trials. ⁶ Recommendations on age vary around the world. In the UK, women are invited for screening once every three years beginning at age 50. Women with one or more first-degree relatives (mother, sister, daughter) with premenopausal breast cancer should begin screening at an earlier age. It is usually suggested to begin at an age 10 years younger than the age when the relative was diagnosed with breast cancer.

Normal (left) versus cancerous (right) mammography image.

Mammography is not as an effective screening technique for women less than 50 years old. Part of the difficulty in interpreting mammograms in younger women stems from breast density. Radiographically, a dense breast has a preponderance of glandular tissue, and younger age or estrogen hormone replacement therapy contribute to mammographic breast density. After menopause, the breast glandular tissue gradually is replaced by fatty tissue, making mammographic interpretation much more accurate. Some authors speculate that part of the contribution of estrogen hormone replacement therapy to breast cancer mortality arises from the issue of increased mammographic breast density.

A systematic review by the American College of Physicians concluded "Although few women 50 years of age or older have risks from mammography that outweigh the benefits, the evidence suggests that more women 40 to 49 years of age have such risks".⁷

Enhancements to mammography

In general, digital mammography and computer-aided mammography have increased the sensitivity of mammograms, but at the cost of more numerous false positive results.^{citation needed}

Computer-aided diagnosis(CAD) Systems may help radiologists to evaluate X-ray images to detect breast cancer in an early stage.^{citation needed} CAD is especially established in US and the Netherlands. It is used in addition to the human evaluation of the diagnostician.

Mammograms and Health Programs

In 2005, 67.9% of all U.S. women age 40–64 had a mammogram in the past two years (74.5% of women with private health insurance, 56.1% of women with Medicaid insurance, 38.1% of currently uninsured women, and 32.9% of women uninsured for > 12 months).⁸ All U.S. states (except Utah) mandate that private health insurance plans and Medicaid provide some coverage for breast cancer screening.⁹ Section 4101 of the Balanced Budget Act of 1997 required that Medicare (available to those aged 65 or older or who have been on Social Security Disability Insurance for over 2 years), effective January 1, 1998, cover and waive the Part B deductible for annual screening mammography in women aged 40 or older.

All organized breast cancer screening programs in Canada offer clinical breast examinations for women aged 40 and over and screening mammography every two years for women aged 50-69.¹⁰ In 2003, about 61% of women aged 50-69 in Canada reported having had a mammogram within the past two years.¹¹

The NHS Breast Screening Programme, the first of its kind in the world, began in 1988 and achieved national coverage in the mid-1990s, provides free breast cancer screening mammography every three years for all women in the UK aged 50 and over.¹² As of March 31, 2006, 75.9% of women aged 53-64 resident in England had been screened at least once in the previous three years.¹³

Criticisms of screening mammography

Several scientific groups however have expressed concern about the public's perceptions of the benefits of breast screening.¹⁴ In 2001, a controversial review published in The Lancet claimed that there is no reliable evidence that screening for breast cancer reduces mortality.¹⁵ The results of this study were widely reported in the popular press.¹⁶

Data reported in the UK Million Woman Study indicates that if 134 mammograms are performed, 20 women will be called back for suspicious findings, and four biopsies will be necessary, to diagnose one cancer. Recall rates are higher in the U.S. than in the UK.¹⁷ The contribution of mammography to the early diagnosis of cancer is controversial, and for those found with benign lesions, mammography can create a high psychological and financial cost. For those diagnosed with cancer, mammography can be the difference in a lumpectomy versus metastatic disease.

Medical Ultrasonography

Medical ultrasonography (Ultrasound) is a diagnostic aid to mammography.

Breast MRI

Magnetic resonance imaging (MRI) has been shown to detect cancers not visible on mammograms, but has long been regarded to have disadvantages. For example, although it is 27-36% more sensitive, it is less specific than mammography.¹⁸ As a result, MRI studies will have more false positives (up to 30%), which may have undesirable financial and psychological costs. It is also a relatively expensive procedure, and one which requires the intravenous injection of a chemical agent to be effective. Further, an MRI may not be used for screening patients with a pace maker or breast reconstruction patients with a tissue expander due to the presence of metal.

Proposed indications for using MRI for screening include:¹⁹

• Strong family history of breast cancer
• Patients with BRCA-1 or BRCA-2 oncogene mutations
• Evaluation of women with breast implants
• History of previous lumpectomy or breast biopsy surgeries
• Axillary metastasis with an unknown primary tumor
• Very dense or scarred breast tissue

However, two studies published in 2007 demonstrated the strengths of MRI-based screening:

• In March 2007, an article published in the New England Journal of Medicine demonstrated that in 3.1% of patients with breast cancer, whose contralateral breast was clinically and mammographically tumor-free, MRI could detect breast cancer. Sensitivity for detection of breast cancer in this study was 91%, specificity 88%.²⁰

• In August 2007, an article published in The Lancet compared MRI breast cancer screening to conventional mammographic screening in 7,319 women. MRI screening was highly more sensitive (97% in the MRI group vs. 56% in the mammography group) in recognizing early high-grade Ductal Carcinoma in situ (DCIS), the most important precursor of invasive carcinoma. Despite the high sensitivity, MRI screening had a positive predictive value of 52%, which is totally accepted for cancer screening tests.²¹ The author of a comment published in the same issue of The Lancet concludes that "MRI outperforms mammography in tumour detection and diagnosis."²²

Breast Cancer and Developing Countries

As developing countries grow and adopt Western culture they also accumulate more disease that has arisen from Western culture and its habits (fat/alcohol intake, smoking, exposure to oral contraceptives, the changing patterns of childbearing and breastfeeding, low parity). For instance, as South America has developed so has the amount of breast cancer. “Breast cancer in less developed countries, such as those in South America, is a major public health issue. It is a leading cause of cancer-related deaths in women in countries such as Argentina, Uruguay, and Brazil. The expected numbers of new cases and deaths due to breast cancer in South America for the year 2001 are approximately 70,000 and 30,000, respectively.” ²³ However, because of a lack of funding and resources, treatment is not always available to those suffering with breast cancer.

BRCA testing

A clinical practice guideline by the US Preventive Services Task Force :⁵

• "recommends against routine referral for genetic counseling or routine breast cancer susceptibility gene (BRCA) testing for women whose family history is not associated with an increased risk for deleterious mutations in breast cancer susceptibility gene 1 (BRCA1) or breast cancer susceptibility gene 2 (BRCA2)" The Task Force gave a grade D recommendation.^{24verification needed}
• "recommends that women whose family history is associated with an increased risk for deleterious mutations in BRCA1 or BRCA2 genes be referred for genetic counseling and evaluation for BRCA testing." The Task Force gave a grade B recommendation.^{24verification needed}

The Task Force noted that about 2% of women have family histories that indicate increased risk as defined by:

• For non–Ashkenazi Jewish women, any of the following:
  • "2 first-degree relatives with breast cancer, 1 of whom received the diagnosis at age 50 years or younger"
  • "3 or more first- or second-degree relatives with breast cancer regardless of age at diagnosis"
  • "both breast and ovarian cancer among first- and second- degree relatives"
  • "a first-degree relative with bilateral breast cancer"
  • "a combination of 2 or more first- or second-degree relatives with ovarian cancer regardless of age at diagnosis"
  • "a first- or second-degree relative with both breast and ovarian cancer at any age"
  • "a history of breast cancer in a male relative."
• "For women of Ashkenazi Jewish heritage, an increased-risk family history includes any first-degree relative (or 2 second-degree relatives on the same side of the family) with breast or ovarian cancer."

References

• Gilberto Schwartsmann (2001) "Breast Cancer in South America: Challenges to improve early detection and medical management of a public health problem." J Clin Oncol 19 118-124

External links

• [1]
• Breast cancer at the Open Directory Project
• Breast cancer screening page from the National Cancer Institute

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