TUESDAY, March 18, 2003 (HealthDayNews) --
Lobular breast cancer rates increased steadily from 1987 to 1999, says a report in the March 19 issue of the Journal of the American Medical Association.
Dr. Christopher I. Li, of the Fred Hutchinson Cancer Research Center in Seattle, and his colleagues analyzed data from nine cancer registries that included information about 190,458 women with invasive breast cancer from 1987 to 1999.
Of those cases, 138,625 (72 percent) were invasive ductal carcinoma (IDC), 14,486 (7.6 percent) were invasive lobular carcinoma (ILC), and 8,860 (4.7 percent) were invasive mixed ductal-lobular carcinoma (IDLC).
The report says the data shows that the incidence rates of tumors classified as lobular increased 1.52-fold between 1987 and 1999, and the incidence of tumors classified as mixed ductal-lobular increased 1.96-fold. Combined, the rates of these types of breast cancers increased 1.65-fold.
The proportion of all breast cancers with a lobular component increased from 9.5 percent in 1987 to 15.6 percent in 1999.
The report notes that previous studies found that women who use or have used combined estrogen-and-progestin hormone replacement therapy have a twofold to 3.9-fold greater risk of ILC, the second most common type of breast cancer.
But those previous studies found that the combined therapy has little impact on the risk of IDC, the most common form of breast cancer.
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