A recent study shows postmenopausal women with new-onset breast tenderness after beginning estrogen and progestin therapy may have an increased risk of breast cancer compared to women who don’t suffer breast tenderness. Researchers from UCLA’s Jonsson Comprehensive Cancer Center conducted the study, which appears in the early online edition of the peer-reviewed journal Breast Cancer Research and Treatment.
For this prospective study, Dr Carolyn Crandall, a professor of general internal medicine and a scientist with UCLA’s Jonsson Comprehensive Cancer Center, and her team researched the relationship between new-onset breast tenderness and change in mammographic density after starting hormone therapy.
The study included 695 women enrolled in the Women’s Health Initiative (WHI). Some participants received estrogen therapy and some received combination hormone therapy. New-onset tenderness was much more evident in women receiving estrogen and progestin therapy compared to women receiving estrogen therapy alone. The correlation between new-onset breast tenderness and changes in breast density also was more distinct in the women taking combination hormone therapy, said Crandall.
Many previous studies have shown a link between higher breast density and a higher risk of breast cancer. According to Crandall, the cancer risk for women with extremely dense breasts can be 4 to 6 times higher than for women whose breasts are not dense.
“These findings parallel what is known about breast cancer risk from the WHI. Breast cancer risk was elevated by combination estrogen and progestin therapy, but not by estrogen alone,” Crandall said. “Now we know that new-onset breast tenderness after combination therapy, but not estrogen alone, is associated with greater increases in breast density.”
These study results emphasize the biology that might partly explain the link between new-onset breast tenderness and increased breast cancer risk during combination therapy, Crandall said. Understanding factors related to mammographic density changes during estrogen and progestin therapy may lead to biological insights regarding hormone therapy–associated breast cancer risk.