Based on this study, we can determine that if a woman is diagnosed with breast cancer, the probability that she actually has cancer is between 0.5% and 9%. After the initial diagnosis indicating cancer, requiring further testing, the woman is likely to have cancer 1 in 200 times. If upon further testing it is determined that she actually does have cancer and treatment is needed (breast removal, radiation, chemotherapy), only 10% of women will actually have needed the treatment -- 90% of them have harmless lesions.
Pamphlets inform women that screening either leads to less invasive surgery or simpler treatment, although it actually results in more surgery, more mastectomies, and more use of radiotherapy because of overdiagnosis. Pain caused by the procedure is sometimes mentioned, although it is probably the least serious harm, as it is temporary. Additionally, none of the information indicates that the tests are wrong over 90% of the time.
"A survey of American and European women found that 68% believed screening reduced their risk of contracting breast cancer, 62% that screening at least halved mortality, and 75% that 10 years of screening saved 10 of 1000 participants (an overestimate of 20 times). Another study showed that only 8% were aware that participation can harm healthy women and that 15% believed their lifetime risk of contracting the disease was more than 50% (an overestimate of five times).
|Breast Cancer Rates|
Yet, this is just one cancer screening test.
Think of the far greater interests advocating other preventive health interventions, such as surrounding obesity, heart disease, cancer, health indices and “healthy” eating. This study serves as a valuable example and reminder that, all too often, health information is more marketing and disease mongering than we may realize."
A pamphlet with information based on objective interpretation of the available studies has been created. It is quite informative and I'd recommend reading it.