Mammography screening has significantly reduced the rates of large tumor and lymph node-positive breast cancer, according to results from the Swedish Organized Service Screening Evaluation Group published in Cancer.
Drafting committee member, Dr. Robert A. Smith, of the American Cancer Society in Atlanta, and associates examined 20 to 40 years worth of observation data for 1.1 million Swedish women. Over this time period there were 23,092 breast cancer cases, representing 10,177,113 person-years of observation.
For women ages 40 to 49 years, mammography screening was associated with significant reductions in the rate of node-positive cancers, tumors larger than 2 cm, and cancers of stage II or higher, the authors report. Significant reductions in all of these three endpoints were also seen among women in the 50- to 69-year-old group.
The combined results for all ages (40 to 69 years) showed 17 percent to 37 percent reductions in later-stage tumors associated with mammographic screening, the researchers note.