Epidemiology of cancer
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.
A related concern is overdiagnosis, the tendency of screening tests to diagnose diseases that may not actually impact the patient's longevity.
These institutions provide information to state and national public health groups to help track trends in cancer diagnosis and treatment.
One of the largest and most important cancer registries is Surveillance Epidemiology and End Results (SEER), administered by the US Federal government.
[5] Health information privacy concerns have led to the restricted use of cancer registry data in the United States Department of Veterans Affairs[6][7][8] and other institutions.
Randomized controlled trials then test whether hypotheses generated by epidemiological studies and laboratory research actually result in reduced cancer incidence and mortality.
[16] Other lifestyle and environmental factors known to affect cancer risk (either beneficially or detrimentally) include the use of exogenous hormones (e.g., hormone replacement therapy causes breast cancer), exposure to ionizing radiation and ultraviolet radiation, and certain occupational and chemical exposures.
[citation needed] A Western diet is associated with increased exposure of the gastrointestinal tract to bile acids that are produced by the body to digest fatty foods.
[18] Millions of workers run the risk of developing cancers such as pleural and peritoneal mesothelioma from inhaling asbestos fibers, or leukemia from exposure to benzene at their workplaces.
[21] In many developing countries cancer incidence, insofar as this can be measured, appears much lower, most likely because of the higher death rates due to infectious disease or injury.
With the increased control over malaria and tuberculosis in some Third World countries, incidence of cancer is expected to rise.
[citation needed] Cancer epidemiology closely mirrors risk factor spread in various countries.
Similarly, with tobacco smoking becoming more common in various Third World countries, lung cancer incidence has increased in a parallel fashion.
They exclude basal and squamous cell skin cancers, and carcinoma in situ in locations other than the urinary bladder.
[citation needed] In 2016, an estimated 1,685,210 new cases of cancer will be diagnosed in the United States and 595,690 people will die from the disease.
[29] The increased risk is believed to be primarily due to the same risk factors that produced the first cancer, such as the person's genetic profile, alcohol and tobacco use, obesity, and environmental exposures, and partly due, in some cases, to the treatment for the first cancer, which might have included mutagenic chemotherapeutic drugs or radiation.
[citation needed] Female and male infants have essentially the same overall cancer incidence rates, a notable difference compared to older children.
