  |
|
|
|
Early detection is a hallmark of curing cancer. All too often, by the time symptoms appear; the cancer has already spread beyond the point where cure is possible. Screening has developed in an attempt to avoid the refrain, “if only we had known sooner.” Screening refers to tests performed on asymptomatic (without symptoms) patients. Screening can be conducted on the population at large, or on selected high-risk groups. Positive results of screening tests, examinations or procedures are usually not diagnostic by themselves, but point the way towards confirmatory diagnoses by biopsy or tissue examinations. The National Cancer Institute 3 has stated two requirements that must be met for screening to be useful: (1) The test or procedure must detect the cancer earlier than if the cancer was detected as a result of the development of symptoms, and (2) There must be evidence that treatment at an earlier stage of disease will result in an improved outcome. As described below, improved outcome should be interpreted to mean improved survival.
Biases Before a patient submits to a screening procedure, he or she should be aware of the pitfalls involved. There are several biases involved in interpreting the positive detection of cancer. 1 Lead-time bias refers to the apparent longer survival time of patients whose cancers were detected by screening. However, this may be simply due to the fact that the cancer was detected at an earlier stage. The patients may not be living longer, they simply find out about their disease earlier. Length-time bias may occur because slower growing, less aggressive tumors have a longer asymptomatic period and are more likely to be detected by screening. Therefore, these patients have a better prognosis than those who have symptomatic disease. Screening bias refers to the possibility that patients who volunteer for screening tend to be healthier than those who do not volunteer. Over-diagnosis refers to detecting cancers that never become a problem clinically. Ethical Considerations A positive result of a cancer screening can create a lot of patient anxiety. This stress can prove unnecessary if follow-up diagnostic tests are negative. If the diagnosis is positive, the patient must weigh the merits of the proposed treatment, especially if it is unproven and potentially dangerous. If the screening procedure is a false negative, the patient can be lulled into a false sense of security. CURRENT STATUS BY CANCER TYPE Breast Cancer – Mammography and clinical breast examinations have proven their worth in detecting breast cancer at its early stages. Numerous major medical organizations recommend the procedures for all women every one or two years beginning at 40 years of age.
The copyright of the article Cancer Screening: When Should it be Considered? in Cancer Treatment is owned by . Permission to republish Cancer Screening: When Should it be Considered? in print or online must be granted by the author in writing.
|
|
|
|
