To determine whether the headline “Mammography screening reduces mortality rates from breast cancer” thatI read in the newspaper was true or not, I used Pubmed as a resource and Idiscovered two published articles that helped me to make an informed decisionon the question at hand. Both articles that I found were original studiesconcluding that mammography screening does in fact reduce the mortality ratesof women with breast cancer.
One of the articles, “Effect of Screening Mammographyon Breast-Cancer Mortality in Norway”, collected data from over 40,000 womenwith breast cancer from 1986 to 2005. Divided into four groups, two of whichhad mammography screening every 2 years and two without any mammographyscreening, the researchers found that there was a 10% decrease in mortalitywhen comparing the groups that were screened versus the groups that were notscreened. The other article I found, “Modern mammography screening and breastcancer mortality: population study” was a cohort study that was trying to determinethe difference in mortality rates between a group that was invited tomammography screenings biennially and a group that received no invitation. Datafor this study was collected from 1986 to 2009. Both studies invited womenbetween the ages of 50 and 69 for mammography screenings. The researchers inthis study found a 28% decrease in mortality due to breast cancer in the groupof women that were invited to mammography screenings. The18% discrepancy between the two studies’ decrease in mortality gives red flagsbut the fact that the second study, with the 28% decrease in mortality ratesdue to mammography screening, adjusted for factors that the first study did notincorporate such as breast cancer mortality trends, nationality, and birthcohorts. This adjustment potentially explains why the second study seemed tohave a larger decrease in mortality rates.
Both studies had found mortalityrate ratios of 0.72 with 95% confidence intervals which gives the impressionthat the data collected was not due to chance and that similar statistics canbe replicated with future studies. The journals that published these articleshave impact factors of 20 (BMJ) and 72 (New England Journal of Medicine) andboth articles were published within the last seven years. Neither is opinionatedor objective and both articles have been peer reviewed. An important note isthat neither study researched women under the age of 50. As a result, I wouldonly recommend mammography screening to those who were inside the age rangeprovided by both studies.
Given all these factors, there is no reason for thedata from either study to be deemed untrustworthy or irrelevant. Based on the data presented from both studiesand my evaluation of the research conducted, I believe that mammographyscreening is effective at reducing breast cancer mortality rates in women aged50 to 69.