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Breast cancer screening

From Breast cancer screening

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Cancer screening
A screening test is a test used to evaluate a population of people for a specific disease without anyone being evaluated ever having any symptoms or signs related to the specific disease. In other words a screening test hunts for a disease before it start producing any symptoms. Screening tests are usually undertaken in a target population, which has significantly high risk of developing the disease. Mammogram is a screening technique used for breast cancer, and the target population for mammogram is women who are aged 40 and above. PSA testing is a screening test for prostate cancer and the target population is men over 50 years of age. Colonoscopy is another screening technique used to detect colon cancer and the target population is men and women over age of 50.

It is not practical to do screening tests for all diseases. A screening test should be able to detect a disease at a very early stage when they are curable or at least treatable. In some cases a useful screening test that can detect the disease in the early stages may not be available, and in some other cases it may not be worth screening for a disease because screening and finding out the disease early may not change the natural history of disease. The later is probably true in case of screening of lung cancer. From the studies so far published, there is no clear evidence to suggest that screening for lung cancer in high-risk population (smokers) would improve survival.

Breast cancer screening
Mammogram is the only accepted screening technique for detection of breast cancer at the current time. Mammogram is a very effective technique for detection of breast cancer at a very early stage when it can be cured or treated. Mammogram till this date may have saved lives of thousands of women, by detecting the disease at a stage, when it is mostly curable. It is important to realize that screening for mammogram does not prevent the occurrence of breast cancer, but instead it provides a very simple and useful technique to detect breast cancer at a very early stage. Mammogram is capable of detecting breast cancer at a stage prior to infiltration of the tumor to the surrounding structures, called stage 0 breast cancer or carcinoma in situ.

Recommendations for breast cancer screening vary from country to country and within the same country according to the views of different organizations who recommend the screening. American Cancer Society recommends that "women age 40 and older should have a screening mammogram every year and should continue to do so for as long as they are in good health."

What is a mammogram?
Mammogram is just an X-ray photograph of your breast, and works in principle the same way as your chest X-ray. The breast tissue is compressed between two plates and an X-ray picture is taken. Doctors would look at the X-ray and determine if there are any abnormalities in the picture. Breast cancer usually appears in the form of calcifications, architectural distortions, or abnormal densities.

Since mammogram uses X-rays, there may be slight risk associated with exposure to radiation in women who get mammograms. However the amount of radiation associated with mammogram examination is very small and is strictly controlled by regulatory agencies like National Department of Health and Human Services. Very strict regulations are enforced by this agency to make sure that mammography equipment is safe and uses the lowest dose of radiation possible. The dose of radiation used by the modern mammogram machines does not significantly increase the risk of breast cancer.

Digital mammography
Digital mammograms are similar to conventional X-ray film mammograms except that the pictures are produced in the digital media in a computer. Digital pictures have the advantages of manipulation of light and contrast. It is possible for the physician to zoom on any suspected abnormality and hence digital mammogram may be more useful for the studying the mammography picture. It was claimed in the past that digital mammogram is superior to conventional mammograms in terms of accuracy, however a recent study has shown that digital mammography is no better than regular mammography.

However the following are some of the advantages of a digital mammogram:
  • Patients are less often called back for more pictures: Since a digital mammogram can be enhanced with respect to light contrast and other picture qualities there is less need for the patient to be called back for additional imaging compared to conventional film based mammogram imaging.
  • Procedure of digital mammogram can cause less anxiety to the patients: The recall and extra picture taking can be associated with significant anxiety on the part of the patient. Since the picture can be immediately reviewed, the necessity for recall and additional filming is decreased, thereby decreasing the anxiety on the part of the patient.
  • Quicker results and less time for appointment for the patient: Digital mammographic picture can be generated on the computer screen within 10 seconds of the procedure and the physician or technician can review the picture and see if it is satisfactory. If the picture is satisfactory the patient can finish the appointment and go home thus saving time for the patient.
  • Digital mammogram can become cheaper: Like any new technology, digital mammogram is currently more expensive than film based mammogram. Since digital mammogram uses electronic medium instead of X-ray film, it is much more cheaper to create the picture. Moreover the cost of storing the digital film is negligible and retrieval is easy compared the conventional film based mammograms. In future digital mammogram will become much cheaper compared to film based mammograms.

Ultrasound imaging of the breast
Ultrasound imaging of breast is a useful technique for evaluating women who were found to have some suspicious lesions in the breast by mammogram. An ultrasound may confirm the presence of a lump that was detected by mammogram. Since ultrasound is able to differentiate between liquid and solid, it is very useful in differentiating cystic (fluid filled) lesions from solid lesion. Ultrasound is not a screening test for breast cancer.

Magnetic resonance breast imaging (MRI)
Magnetic resonance breast imaging (MRI) is very useful technique for breast imaging. This technique currently approved by U.S. Food and Drug Administration (FDA) as a supplemental tool to mammogram. Magnetic resonance breast imaging (MRI) of the breast is usually performed when mammogram or ultrasound of the breast is abnormal, but cannot determine the nature of the abnormality. Magnetic resonance breast imaging (MRI) of the breast is also a useful technique to imagine breast that has an implant. Magnetic resonance breast imaging (MRI) may be useful in screening younger women who have significant risk of developing breast cancer as in the case of BRCA1 or BRCA2 carriers. Mammograms may not very useful in some of these patients due to increased density of breast in younger women. This use is experimental and is currently undergoing studies. It is to be emphasized that the only FDA approved screening tool at the time of writing this article is mammogram.

Computer Aided Detection (CAD)
CAD is sophisticated computer program that can compare areas of the digital mammography picture and aid the physician to more easily detect breast cancer. Studies have shown that CAD system improved diagnostic accuracy by about 20 percent. CAD systems are useful for reading digital mammograms ultrasounds and MRI.

A study presented at the 2005 European Congress of Radiology (ECR) meeting demonstrates that CADstream, computer-aided-detection (CAD) for breast MRI, may improve diagnostic accuracy and increase efficiency of breast MRI analysis. This study compared CADstream to standard software used for MRI analysis, focusing on diagnostic accuracy and efficiency. The study concluded that CADstream may improve diagnostic accuracy and increased efficiency for breast cancer evaluation. The CAD system showed a significant reduction in image artifact, helping the radiologist with more accurate analysis and saving a substantial amount of time during analysis of breast MRI studies. The study showed that CADstream significantly reduces patient movement-related artifact and analysis time, assisting radiologists in more accurately and efficiently interpreting studies.

CADstream enhances the efficiency and workflow of breast MRI studies by automating data analysis, improving image management and correcting for patient movement, which assists radiologists in the interpretation, standardization and reporting of these data-intensive studies. CADstream's core automated features include adaptive image registration (2D/3D), multiplanar reformatting, subtractions, angiogenesis maps, interactive real-time contrast curves, maximum intensity projections (MIPs) and volume summaries.

In a recent study presented by Anna Bilska-Wolack PhD from Duke University, at the Era of Hope Department of Defense Breast Cancer Research Program meeting (2005) the accuracy rate of a new computer system to read mammograms was explained. In this study a computer algorithm known as likelihood ratio (LRb) classifier is shown to be very effective in detecting breast cancer in mammograms. Likely ratio classifier is capable detecting breast cancer in mammograms with 100 percent accuracy. Likelihood ratio (LRb) classifier uses an optical technique that mathematically calculates the data from signal processing to decide if the presented signal represents a breast malignancy. The computer program was developed from a large database of mammograms which was biopsy proven to have breast cancer. The likelihood ratio (LRb) classifier has also been shown to be accurate in sets of mammogram that were not involved in developing this computer program.

Digital Infrared Thermal Imaging (DITI)
Thermography is method of detecting abnormal temperature areas in organs like breast. Thermography is the technique of imaging based on heat emission. Thermography helps physicians to identify tumors like breast cancer. The term thermography literally means writing with heat or writing heat. This equipment uses infrared head released from the tumor with the help of modern digital equipment to correctly map the presence of abnormality in areas like breast.

Modern digital technology has integrated digital imaging with thermography in technique called Digital Infrared Thermal Imaging (DITI). The Food and Drug Administration (FDA) approved Digital Infrared Thermal Imaging (DITI) n 1982 for additional evaluation of patients who were found to have suspicious lesions in the breast. Thermal cameras detect heat given off by the body and display it as a picture on a computer monitor. These images are unique to the person and they remain stable over time. It is because of these characteristics that thermal imaging is a valuable and effective screening tool to determine changes that could point to trouble down the road. As we all know, early cancer detection is important to survival. Thermography measures temperature changes in the body. Tumors create their own blood vessels. Where there are more blood vessels, there is more heat. It is in these areas on the body that the camera detects changes in heat or temperature.

Unlike mammography, there is no radiation exposure involved with Digital Infrared Thermal Imaging (DITI). Mammogram involve compression of the breast which is often painful and the use fo Digital Infrared Thermal Imaging (DITI) eliminate the need for compression.

Thermography does not replace mammography. However, it is an additional tool that is available to women. By combining both technologies, the detection rate increases to 95-98%, surpassing either technology as a stand-alone therapy.

Clinical breast examination and self breast examination
An article on breast cancer screening will not be complete without mentioning clinical breast examination and (CBE) and self breast examination (SBE). CBE and SBE are useful adjuvant to mammogram for detection of breast cancer. It is also to be mentioned that about 10 percent of all tumors that can be felt by the physicians may not be seen in a mammogram, hence if the physician feels a tumor, the absence of abnormality in the mammogram does not ensure absence of a breast tumor. Such patients should be evaluated by biopsy.

Self-breast examination as the name implies denotes examination of breast by women, without the help of a physician. This can be undertaken in the privacy of their home. Probably the best time to do a self-breast examination is while taking showers. Women can ask their physicians to teach them the technique of self-breast examination. American Cancer Society recommends "women in 20s and 30s should have a clinical breast examination (CBE) as part of a periodic (regular) health exam by a health professional preferably every 3 years. After age 40, women should have a breast exam by a health professional every year." Regarding self-breast examination, American Cancer Society gives the following recommendations:
"BSE is an option for women starting in their 20s. Women should be told about the benefits and limitations of BSE. Women should report any breast changes to their health professional right away."

By Scott Willam

Did you know?
Mammogram is just an X-ray photograph of your breast, and works in principle the same way as your chest X-ray. The breast tissue is compressed between two plates and an X-ray picture is taken. Doctors would look at the X-ray and determine if there are any abnormalities in the picture. Breast cancer usually appears in the form of calcifications, architectural distortions, or abnormal densities Breast cancer screening

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