Variation in mammographic density during menstrual cycle Free

A54

Background: The sensitivity of mammography for cancer detection is less in women aged 40-49 compared to older women, due in part to more extensive mammographic density in younger women. To improve the quality of screening it has been suggested that premenopausal women to be examined in the follicular phase of the menstrual cycle, when density is thought to be less extensive than in the luteal phase. We have examined the extent to which mammographic density and dense area vary according to the menstrual cycle.
 >Methods: Premenopausal women aged 40-49 with regular menstrual cycles, without a history of breast disease, and who had mammograms at Sunnybrook/Women’s College or Mount Sinai Hospitals participated in the study. We measured percent breast density, breast area, and dense area using the Cumulus software. Dates of the first day of the last and next menstrual cycles (NMC) were determined by follow-up phone calls. To determine the time in the cycle when the mammogram was taken, the interval between mammogram date and the date of the start of NMC was calculated, and divided into 4 intervals: interval 1 (>21 days before NMC), interval 2 (15-21 days before NMC), interval 3 (8-14 days before NMC) and Interval-4 (≤7 days before NMC).
 >Results: The total number of subjects included in the analysis was 419: 77 in interval 1, 109 in interval 2, 105 in interval 3 and 128 in interval 4. The least square means of dense area after adjusting for age, BMI, breast thickness and mammography machine characteristics ( KV, MAS and Pressure), were 51.4 cm², 49.6 cm², 50.7 cm² and 55.5 cm² during intervals 1-4 respectively, however, the results were not statistically significant. The adjusted least square means of percent density were 41.7%, 39.5%, 40.5%and 41.9% during intervals 1-4 respectively; the results were not statistically significant. There were no significant variations between different intervals with regards to mammographic density after adjusting for age, BMI, breast thickness and mammography machine characteristics, such as KV, MAS and Pressure.
 >Conclusion: There was no difference in mammographic density in relation to the time of mammography after adjusting for machine parameters. Data do not support the suggestion that premenopausal women would benefit from having mammographic examination in the follicular phase of menstrual cycle.