''This analysis says the limiting factor is not the difference in doubling time of the breast cancer," Plevritis concluded. "The limiting factor is the ability of the mammogram to detect the tumor."
She pointed out that she studied women who had conventional mammograms only. "Technology with conventional mammography is just not sensitive enough," Plevritis said. "That explains 79 percent of the reduced detection rate." The characteristics of the cancer itself in younger women account for just 21 percent of the shortfall in detection, the model found.
The findings were published online July 27 in the The Journal of the National Cancer Institute.
Plevritis said that because she evaluated women who had conventional mammography only, the results may be different with more advanced digital mammography. Some research has found digital more accurate in detecting tumors in women 40 to 49, she said.
That's beyond the scope of her paper, "but our work is suggesting that the performance of digital mammography in younger women will make a difference," Plevritis said.
Another limitation of her study, she said, is that they looked at only invasive disease, not the early form of breast cancer known as ductal carcinoma in situ or DCIS. "The natural history of DCIS is not well understood," she said.
For now, she said, younger women below age 50 might consider asking for digital mammograms. Advances in technologies are needed, she said, to better detect breast cancers in younger women.
There's more on breast cancer screening at the American Cancer Society.
SOURCES: Sylvia Plevritis, Ph.D., associate professor, radiology, Stanford University School of Medicine, Stanford, Calif.; July 27, 2010, Journal of the National Cancer Institute
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