E. Conant (Philadelphia, AL, United States of America)
Perelman School of Medicine, University of PennsylvaniaAuthor Of 1 Presentation
75P - Use of Low-dose Tamoxifen to Improve Mammographic Screening Sensitivity in Premenopausal Women
Abstract
Background
High mammographic density decreases the sensitivity of mammography. Tamoxifen reduces mammographic density and could therefore increase the sensitivity of a mammogram. We tested if low-dose tamoxifen could be used to increase the sensitivity of mammography in premenopausal women.
Methods
The study was based on the KARMA prospective screening cohort including 28,282 premenopausal women and 517 incident breast cancers. Mammographic density was measured as percent density and as a computerized BI-RADS score using the STRATUS tool. Mammographic density-dependent screening sensitivities and tumor sizes were estimated in each of the four BI-RADS categories (A, B, C, D). The 2.5 mg tamoxifen arm of the KARISMA tamoxifen six-month trial was used to define the change of mammographic density that we would observe in KARMA, if the women were exposed to low-dose tamoxifen for 6 months. Screening sensitivities and tumor sizes were predicted in the KARMA cohort assuming all women were exposed to 2.5 mg of tamoxifen. Reduction in interval and advanced cancers were estimated in women with relative mammographic density decreases from 10% to 50%.
Results
During the 8-year follow-up, 287 (56%) screening-detected and 230 (44%) interval cancers were diagnosed in the KARMA cohort. The screening sensitivities before exposure to tamoxifen were 77%, 69%, 53%, 46% for the BI-RADS categories A, B, C and D. The mean density decrease after exposure to 2.5 mg of tamoxifen was 15.4% and the BI-RADS category-dependent change in sensitivity was 0% (p=0.95), 2% (p=0.01), 4% (p<0.001), and 5% (p<0.001), respectively. A density decrease of ≥20% reduced the number of interval cancers by 24% (p<0.01) and the probability of identifying >20 mm tumors by 4% (p<0.01).
Conclusions
Low-dose tamoxifen has the potential to increase the sensitivity of a screening mammogram and therefore reduce the proportion of interval and advanced cancers in mammography screening.
Legal entity responsible for the study
Hans and Märit Raussing, Kamprad Foundation.
Funding
Hans and Märit Raussing, Kamprad Foundation.
Disclosure
All authors have declared no conflicts of interest.