Epidemiology and Cancers
The epidemiology of cancer is the study of the aspects affecting cancer, as a way to infer probable trends and causes. The study of cancer epidemiology customs epidemiological methods to find the source of cancer and to recognize and develop improved treatments. This extent of study must contend with glitches of lead time bias and length time bias. Lead time bias is the concept that early diagnosis may artificially inflate the survival statistics of a cancer, without really improving the natural history of the disease. Length bias is the perception that slower growing, more indolent tumors are more likely to be analyzed by screening tests, but improvements in diagnosing more cases of indolent cancer may not interpret into better patient outcomes after the execution of screening programs. An associated concern is over diagnosis, the tendency of screening tests to detect diseases that may not actually impact the patient's longevity. This problem especially applies to prostate cancer and PSA screening.