CANCER SCREENING

Preventive Medicine
CANCER SCREENING
A 39-year-old woman comes to the clinic very concerned about her risk of developing cancer. When questioned further she attests to a family history of colon cancer—her father was diagnosed at the age of 43, and her mother was diagnosed with breast cancer at the age of 52. The patient states that she is sexually active with multiple partners and has not seen a physician since a motor vehicle accident that occurred 15 years ago. She denies any symptoms at this time, and physical examination is normal. At the end of the interview she asks what is recommended for a woman her age.
Screening is testing done on seemingly healthy people to identify those at increased risk of disease. Potentially, several harmful effects may result from screening tests. Any adverse outcome that occurs (large bowel perforation secondary to a colonoscopy) is iatrogenic. Screening may be expensive, unpleasant, and/or inconvenient. Screening may also lead to harmful treatment. Finally, there may be a stigma associated with incorrectly labeling a patient as “sick”.
Even if a test is available, that does not necessarily mean it should be used to screen for a particular disease. For all diseases for which screening is recommended, effective intervention must exist, and the course of events after a positive test result must be discussed with and be accept( able to the patient. Most important, the screening test must be valid; i.e., the test must have been
shown in a randomized, double-blinded trial to decrease overall mortality in the screened population.
For a screening test to be recommended for regular use it has to be extensively studied to insure that all of the above requirements are met. The three malignancies for which regular screening is recommended are cancers of the colon, breast, and cervix.
In the patient with no significant family history of colon cancer, screening should begin at the age of 50. The choices are annual fecal occult blood testing, sigmoidoscopy every 5 years, and barium enema. The preferred screening modality for colon cancer is colonoscopy every 10 years.
Patients who have a single first-degree relative with colorectal cancer diagnosed before the age of 60, or who have multiple first-degree relatives with colon cancer at any age, should undergo colonoscopy starting either at the age of 40 or at an age that is 10 years younger than the age at which the youngest affected relative was diagnosed, whichever age occurs earlier. In this group of high-risk patients, colonoscopy should be repeated every 5 years.