BENEFIT OF MAMMOGRAPHY SCREENING IN WOMEN AGES 40 TO 49 YEARS - CURRENT EVIDENCE FROM RANDOMIZED CONTROLLED TRIALS

Background. Eight randomized controlled trials (RCTs) of screening mam mography were conducted involving women ages 40 to 49 years at entry. Current data gathered for periods ranging from 7 to 18 years of follow -up are available from these trials. Methods. Meta-analyses were perfo rmed using a Mantel-Haenszel estimator method to combine current follo w-up data from the eight RCTs of mammography that included women ages 40 to 49 years. Results. Combining all current data on women ages 40 t o 49 years at entry into the trials yielded a 14% benefit from screeni ng mammography, without statistical significance at the 95% confidence level. Combining all data on women ages 49 to 49 years at entry, excl uding results from the Canadian National Breast Screening Study, yield ed a 23% benefit to women invited for screening, with statistical sign ificance at the 95% confidence level. Conclusions. These results sugge st that screening mammography in women ages 40 to 49 years at entry ca n reduce mortality from breast cancer when combined with adequate foll ow-up.