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At present the evidence shows mass population screening is effective only for cervical, breast and oral cancers. In a few countries like Japan or Costa Rica where the incidence of stomach cancer is very high special radiological screening tests may be used. Stool occult blood and sigmoidoscopy and/or colonoscopy are used to detect colorectal cancer and polyps, but their application to mass population screening is still under evaluation. X-ray and cytology have not been found to be useful to screen for lung cancer. Systematic inspection of the skin with biopsy of suspicious lesions can detect early skin cancer or melanoma, but is useful only in high risk patients. Urinary cytology may be used to screen individuals at high risk for bladder cancer (endemic schistosomiasis or occupational exposure to carcinogens), but the in situ lesion often covers most of the bladder lining making it difficult to treat surgically. The advent of BCG immunotherapy addresses this difficulty.
Screening for cancer sites listed on this slide such as esophagus, stomach, colon and rectum, liver, lung, ovary, bladder and prostate are still considered experimental and under evaluation.
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