Mammographic Density Reduction Is a Prognostic Marker of Response to Adjuvant Tamoxifen Therapy in Postmenopausal Patients With Breast Cancer
Tamoxifen treatment is associated with a reduction in mammographic density and an improved
survival. However, the extent to which change in mammographic density during adjuvant
tamoxifen therapy can be used to measure response to treatment is unknown.
Overall, 974 postmenopausal patients with breast cancer who had both a baseline and a follow-up
mammogram were eligible for analysis. On the basis of treatment information abstracted from
medical records, 474 patients received tamoxifen treatment and 500 did not. Mammographic
density was measured by using an automated thresholding method and expressed as absolute
dense area. Change in mammographic density was calculated as percentage change from
baseline. Survival analysis was performed by using delayed-entry Cox proportional hazards
regression models, with death as a result of breast cancer as the end point. Analyses were
adjusted for a range of patient and tumor characteristics.
During a 15-year follow-up, 121 patients (12.4%) died from breast cancer. Women treated with
tamoxifen who experienced a relative density reduction of more than 20% between baseline and
first follow-up mammogram had a reduced risk of death as a result of breast cancer of 50% (hazard
ratio, 0.50; 95% CI, 0.27 to 0.93) compared with women with stable mammographic density. In
the no-tamoxifen group, there was no statistically significant association between mammographic
density change and survival. The survival advantage was not observed when absolute dense areas
at baseline or follow-up were evaluated separately.
A decrease in mammographic density after breast cancer diagnosis appears to serve as a
prognostic marker for improved long-term survival in patients receiving adjuvant tamoxifen, and
these data should be externally validated.
Jingmei Li, Keith Humphreys, Louise Eriksson, Gustaf Edgren, Kamila Czene, and Per Hall