Postmenopausal Shrinkage of Uterine Myomas: A Retrospective Study of 97 Cases Monitored Annually for 10 Years

Introduction and aim Both patients and gynecologists are concerned about how much and how quickly myomas shrink after menopause. This study aimed to elucidate clinical findings that may be associated with postmenopausal shrinkage of uterine myomas. Materials and methods This study included 97 patients who underwent menopause by August 2012, had myoma nodules with the longest diameter between 50 mm and 160 mm, and visited our specialized myoma clinic annually for at least 10 years after menopause. They underwent transabdominal ultrasonography at least once per year. An experienced gynecologist measured the longest diameter of myoma nodules with a maximum diameter between 50 mm and 160 mm. The shrinkage rate of myoma diameters after menopause compared to premenopausal diameters was calculated each year for 10 years. The shrinkage rate of the longest diameter of the largest nodule 10 years after menopause (10-year shrinkage rate) and its relationship with clinical findings (the age at menopause, parity, body mass index {BMI}, number of nodules, MRI findings on T2-weighted image, location of the nodule, and longest diameter of the largest nodule before menopause) were analyzed. Additionally, we examined annual changes in shrinkage rate of myomas over a 10-year period after menopause (annual trend), and the relationship between annual trends and factors such as BMI and the number of nodules. Results In this examination of 10-year shrinkage rate, the group with a BMI of less than 25 showed a significantly greater shrinkage rate compared to the group with a BMI of 25 or more (25.0% vs 15.7%, p=0.023). Additionally, the group with a single nodule showed a significantly greater 10-year shrinkage rate compared to the group with four or more nodules (26.3% vs 15.2%, p=0.036). For annual trends, the rate of change in the first two years after menopause was significantly faster compared to the trend from the third to the 10th year (difference in slope: 3.888 points per year, p<0.001). When divided into two groups based on the number of nodules (one or two nodules group and three or more nodules group), the group with one or two nodules showed a significant difference in the shrinkage rate between up to two years after menopause and from the period from the third to the 10th year (difference in slope: 4.590 points per year, p<0.001). However, for the group with three or more nodules, there was no significant difference in the annual trend between the first two years after menopause and the rate from the third to the 10th year (difference in slope: 1.626 points per year, p=0.107). Conclusion BMI and the number of myoma nodules were significantly related to the 10-year shrinkage rate. Although myomas shrank significantly faster within the first two years after menopause compared to the later period, the early annual trend did not differ significantly from the trend in the later period when there were multiple nodules with a maximum diameter of 50 mm or more.