Early ovarian cancer is one with no symptoms to warn of its growth, so it's rarely detected before an advanced stage. Even cancers that exhibit warning signs aren't always recognized in time for the most effective therapies. So strong is the dread of cancer that many people shy from self-examination techniques for fear that they will reveal the disease. Even when such simple self-examinations are performed conscientiously, they can detect only tumors large enough to feel, which are therefore already somewhat developed. About 80 percent of breast lumps are not cancerous.
Early detection increases survival rates for some cancers dramatically.
If all melanomas were detected while still small and confined to one area, the cure rate could approach 100 percent. Three-fourths of colon or rectal cancer patients could be saved by early detection. Shields works on devising tests to determine who is at increased risk of developing a cancer. He studies oncogenes, which in many cases started as normal genes regulating cell growth. Suppressor genes, which inhibit cell growth, oppose oncogenes.