Mammograms Best Done in the First Week of the Cycle

Controversy still exists about the actual value of mammograms in diagnosing breast cancer adequately, but there seems to be one way to enhance their usefulness – have one in the first week of the menstrual cycle.  That’s the finding of a study done in Seattle, and published in the journal Radiology.

A review was done of 387,218 screening mammograms in premenopausal women that were linked to 1,283 cases of breast cancer.  The differences in screening performance were estimated according to the week of the subject’s menstrual cycle, with appropriate adjustments for age and mammography register differences. 

At first glance, the screening performance of mammography did not differ, overall, according to the week of the subject’s menstrual cycle.  However, if the analyses were subdivided according to prior mammography, differences became evident.  Two-thirds of the women had had regular screenings within the last 2 years, and in them, the sensitivity was higher in the first week of their cycle – 79.5% - compared with the subsequent weeks – 70.3%, 67.4%, and 73%, respectively.   (The reverse was the case in the 18% of women who had mammography for the first time.)  

This finding suggests that premenopausal women time their mammography exams during the first week of their cycle to enhance the chances of detecting a tumor, if one is present.  Another possible advantage of this approach is that it could decrease discomfort during mammography, as breast tenderness is more usual in the second half of the cycle.

Unfortunately the authors of this study can offer no explanation for the reverse trend in sensitivity of tumor detection seen in first-time mammography subjects.  They state that additional studies are warranted to understand these findings . . .