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Screening for some cancers does more harm than good
Some tumors never show themselves. Australian scientists estimate that after the introduction of screening for certain types of cancer, one in four cancer diagnoses in men and one in five in women were “optional”. In such cases, treatment can do more harm than good.
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The advent of cancer screening and routine tumor marker tests is saving many lives around the world. But not all abnormal cells are dangerous. Scientists at the University of Bond have calculated the risk of "overdiagnosis" for five different cancers for the first time. The study is published in the Medical Journal of Australia.
“Cancer treatments - surgery, radiation and hormone therapy, chemotherapy - can cause physical harm, but the risks are considered acceptable if the diagnosis was appropriate. However, if someone is diagnosed with an optional cancer diagnosis, treatment can only harm, not help,”the study authors explained.
Scientists found that in 2012 (compared to 1982), Australian patients were much more likely to be diagnosed with cancer, although deaths from it did not increase.
According to experts, in 2012, every fourth cancer diagnosis in men was optional (in particular, 42% of cases of prostate cancer, 42% of kidney cancer, 73% of thyroid gland and 58% of melanomas) and almost every fifth in women (73% cases of thyroid cancer, 22% of breast cancer and 54% of melanomas).
In other words, there were 29,000 cancer diagnoses (11,000 cancers in women and 18,000 in men) that may not have required diagnosis or treatment.
Most often diagnosed with breast and prostate cancer, for screening which, even in the absence of symptoms, in a number of countries around the world adopted extensive national programs.
“Sometimes screening will reveal abnormal cells that look like cancer but don't behave like cancer. However, it is not easy to solve this problem because some types of screening are important,”said study leader Paul Glasziou.
A Danish study found that mammographic examinations do not reduce the number of advanced tumors and very often reveal small tumors that may not pose a risk. For every life saved from cancer, screening accounts for about three cases of overdiagnosis, according to British studies. An analysis of data collected over 40 years in the United States revealed that the incidence of thyroid cancer, kidney cancer and melanoma is rising sharply, but the death rate from them has remained practically unchanged.
Striking a balance between too few and too few diagnostic tests is critical for public health. More data is needed to help clarify a number of issues related to the extent of overdiagnosis and the benefits of screening.