Screening (Cervical, Breast, and Colon Cancers)

CANCER SCREENING IS a medical test that looks for cancer before a person displays any symptoms. The fundamental idea behind screening is that by identifying the cancer early, the cancer will be less developed and easier to treat. As with many cancers, by the time physical symptoms of the cancer appear, the cancer has already spread to other locations in the body.

The primary goal of cancer screening is to find the cancer as early as possible so that the patient has the best chance of survival. Studies of cancer patients have found that the survival of individuals with solid, malignant cancers is strongly influenced by how far the disease has progressed when the cancer is diagnosed. Patients with cancers that are located only at the initial site of the cancer growth have a lower risk of the cancer returning after treatment than patients who have cancers that have spread to other locations in the body.

The secondary goals for cancer screening are a reduction in the need for extensive and often debilitating cancer treatments, a decreased cost in cancer treatment, and an improved or maintained lifestyle of [Page 772]the patient after diagnosis. First, if a cancer is diagnosed when it is small and localized to the original site of growth, then less drastic treatment will be needed. For example, a 0.5-cm breast tumor that is localized only in the breast will require less tissue to be removed surgically than a 10-cm breast tumor that has spread to the lymph nodes. In addition, decreased medical costs for treatment go hand in hand with the less invasive treatment procedures used when cancer is detected early. Because the less invasive treatments for early-stage cancers have fewer procedural complications, the costs of nursing care and medications tend to be less than treatment costs associated with more advanced cancers. Furthermore, patients usually can lead a more productive life with less invasive cancer treatments that typically have shorter recovery times.

Screening for cancer is not alwaysjustified, especially when early detection of the cancer may not improve the disease outcome for an individual with a positive screening result. For screening to be beneficial, effective clinical treatments must be in place. If the current methods of treatment are incapable of affecting tumor growth and spread at an early stage of disease, then the early diagnosis via screening may be more distressing to the patient than helpful. Successful cancer screening tests must reduce the burden of suffering, decrease cancer frequency, accurately and reliably detect the cancer, and be relatively safe and low cost.

There are a few potential adverse effects from cancer screening. In some cases, the test procedure may have complications. Depending on the cancer prevalence, physicians must weigh the benefit from the screen to the few who are saved against the potential danger of the screen to everyone who was tested. Common adverse effects of screening include false-positive results, when the test identifies that cancer is present when it is not present, or false-negative results, when the test wrongly indicates that cancer is not present when it actually is there. A false-positive result can cause undo worry for the patient, who usually must undergo further, often invasive, medical tests. In contrast, a false-negative result may prevent a patient from obtaining much needed treatment. These potential adverse effects of screening must be compared to its potential benefits when assessing whether to implement or participate in cancer screening.

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