Health services play an important role in secondary prevention of late and untreatable stages of cancers. They recommend, prepare and provide large actions focused on detection of early, asymptomatic and treatable stages of the disease. Screening programs should be applicable in the society as a whole and available to everybody. They concentrate on diseases in initial treatable stage with high population incidence. Detection methods should be safe, noninvasive and cost beneficial. Screening strategies for carcinoma of the cervix, breast and colorectal carcinoma are the best. Tertial prevention is targeted to prevention of disease progression and suffering.