A mammogram each year or even half-yearly as a part of getting a routine check-up is all fine, but there is a 10 percent risk of being diagnosed with breast tumors that would otherwise never progress enough to cause significant problems, according to a report by Swedish researchers in the March 4 edition of the British Medical Journal.
"We found that one in 10 breast cancers detected by screening mammography may be over-diagnosed," observed Dr. Sophia Zackrisson of Malmo University Hospital in Sweden. "It means that in the absence of screening, the tumour would never have given any symptoms in its host."
Previous studies on the "over diagnosis" of such relatively harmless growths had attributed a 54 percent chance of routine procedures detecting such conditions, but Zackrisson, who is a radiologist from the Epidemiological Research Group at the hospital said that previous studies had probably overestimated this risk since their study found a lower percentage of these incidences, "Over-diagnosis has to be put into perspective together with the number of lives saved by screening and other costs and benefits," she stressed.
For this particular study, the reserachers used data from a decade-long breast cancer screening trial conducted between 1976 and 1986 in Sweden. Around 42,283, women aged 55 to 69 took part in the trial. These women were followed up until 2001 and researchers monitored the number of breast cancer incidences during this period. After thoroughly checking up on the prevailing rates, researchers arrived at the conclusion that 10 percent of breast cancers are over diagnosed.
"It is necessary to know more about the biologic characteristics of these tumors," Zackrisson said. "Today, it is not possible to know which tumors are over-diagnosed. Until we know more, we have to go on with the same treatment for all tumors." She added that women should be aware of this risk when they went in for screening. However, "this is just one side of screening -- women should be informed about all positive and negative effects of screening," Zackrisson cautioned.
