Claims about the Ineffectiveness of Mammography Screening Are Incorrect

​Press Release – University of Turku 14th of November, 2014

International scientific discussion has recently debated about the benefits of mammography and the overdiagnosis that are connected with it.

– One researcher has stated that even 30 percent of the breast cancer diagnoses made with mammography are overdiagnosed. My research revealed that the number is about ten percent. The research results did not lend support to the widely expressed scientific interpretations, often recounted in the international media, which suggest that we could give up the mammography screening programmes, says Parvinen.

Parvinen’s dissertation research is based on the results of the extensive screenings of women in Finland. The data covered over 40 million women years.

The research included all the women aged 40–84 in Helsinki, Turku and the rest of Finland. The screening results covered a time period of 23 years which was compared in the analysis section with an 11-year period that preceded the screening programmes. What makes the comparison interesting is that Turku included all women aged 40–74 in the mammography screening from the beginning but Helsinki called only 50–55-year-old women to the screenings at first. The standard for the screening programmes in the whole country was 50–59.

– The results suggest that in Turku the decrease in breast cancer mortality, especially among the older age groups, is a result of the extensive mammography screening programme of the city, says Parvinen.

Turku’s result in the decrease in breast cancer mortality rose to the top internationally during the first decade of the 21st century. According to Parvinen, two things made this possible:

– The breast cancer mortality of the younger age group dropped by over a half compared with the level prior to the screenings and in the oldest age group, women of over 75, breast cancer mortality was reduced by over 25 percent proportionately to the other areas, says Parvinen.

Statistical evidence which supports the notion that the top results were caused only by the effects of the screening was found for the older age group but not for the younger one.

– All in all, it seems that over a hundred women survived breast cancer because of the screenings. If the screening had been more restricted in Turku, similar to that of the standard of the whole country, the number would have been only a fraction of the achieved result, says Parvinen.

He states that according to his own results and the earlier results published in Finland, the deaths of as many as 2000 Finnish breast cancer patients could have been avoided during the 23-year follow-up period if the whole country had followed the mammography screening model of Turku.