In just about a month's time, five percent of breast tumors appear to double in size. Researchers reporting in the Journal "Breast cancer Research" say their finding underscores the potential benefit of more frequent screening.
The study involved data on nearly four-hundred thousand women between the ages of fifty and sixty-nine.
Using a complicated formula, they calculated that about five percent of tumors will double in size in a little over four weeks.
The faster-growing tumors were mainly among younger women in the study's age group.
Researchers are hoping the report will help in the debate over how often women should get mammograms.