Community-based epidemiological study is indispensible for exploration of cancer etiology and evaluation of cancer prophylaxis and control

With the increasing ageing tendency of population, cardiovascular diseases and malignancies are the major causes of human death in China.Malignant diseases are the major cause of death of subjects who died prior to the average life expectancy, especially for the working population (60 years or less).For disease control prospective, malignant diseases can be classified into three categories.First category is the highly malignant tumors including pancreas cancer, liver cancer, gastrointestinal signet ring cell cancer, and small cell lung cancer.Malignancies of this category progress rapidly and respond poorly to routine therapy.The emphasis of controlling malignancies of this category is the etiological prevention, that is, first-grade prophylaxis, to reduce the incidence.Second category is moderately malignancies including colorectal cancer, non-small cell lung cancer, and female breast cancer.Malignancies of this category progress moderately and respond better to routine therapy.Moreover, malignancies of this category usually have precancerous lesions.Treatments for the precancerous lesions such as surgical resection can greatly reduce the incidences. Malignancies of this category are suitable for early screening, early diagnosis, and early treatment, namely second-grade prophylaxis, to reduce the mortality.Third category is "lazy"malignancies including prostate cancer and thyroid cancer.Malignancies of this category did not damage the life expectancy of affected population significantly.Furthermore, active treatments for malignancies of this category do not improve effective survival.The emphasis of controlling malignancies of this category is to treat the metastasis, namely, third-grade prophylaxis.Over-diagnosis and over-treatment for malignancies without classification not only cause damages to patients' sprit and economy, but also are unprofitable to effective survival of patients.Over-diagnosis and over-treatment also waste public medical resources.Elucidation of cancer etiology and evaluation of the epidemic situation, disease burden, prophylactic effect, and therapeutic effects of various clinical treatments for malignancies rely on community-based epidemiological research.