Previous studies have shown that the incidence of Uterine leiomyoma (UL) in postmenopausal women decreases with decreasing hormone levels[33]. Generally, when UL in postmenopausal women becomes large and associated with symptoms such as vitreous degeneration, mucous degeneration, steatosis, red degeneration, cystic degeneration and calcification, surgical treatment is considered. In severe cases, malignant transformation may occur [34,35].
UL degeneration is generally a primary indication for surgery in postmenopausal women. The decision to perform surgery is largely based on a comprehensive assessment by clinicians, taking into account factors such as the patient's symptoms, the size of the UL and the trend of UL change. Although surgery is an effective treatment option, it is important that patients are thoroughly assessed before surgery, taking into account the physical and psychological trauma of surgery, particularly in postmenopausal women, as well as the socio-economic impact of surgery. However, there is a paucity of research on the risk of UL degeneration in postmenopausal women and no relevant studies of the nomogram have been conducted. In this study, we analysed 29 potential variables of UL in 508 postmenopausal women who underwent hysteromyoma-related surgery (myomectomy or hysterectomy). A simple and easy-to-use prediction nomogram for UL in postmenopausal women using multivariate analysis was developed for the first time. Seven variables (DM,BRASTCANCER, NUMBER, size5 ,LDH, TG, Ca2+)were filtered for the nomogram using stepwise regression. This nomogram had a good diagnostic performance (AUC = 0.714) and was validated internally using the bootstrap sampling method. Furthermore, this prediction model showed superior performance when used in the clinical setting based on the results of the DCA. More importantly, compared to the clinical experience model (sym+ changetrend+ size5) in AUC, DCA and NRI, the prediction model we built has greater advantages in predicting the outcome of UL degeneration.
This study found that the likelihood of uterine leiomyoma (UL) degeneration in postmenopausal women was 40.6%, which is lower than the 65-66% reported in previous literature [36,37]. After menopause, serum estrogens and progesterone levels decrease significantly, resulting in a reduced likelihood of UL growth. Therefore, only a few cases of UL have been reported in postmenopausal women [38-41] .Interestingly, researchers[42] have found no discernible difference in the expression of sex steroid hormone receptors between postmenopausal UL that required surgery and those that did not. These findings suggest that sex steroid hormones may play a less important role in the growth of postmenopausal UL. In general, we believe that enlargement of postmenopausal UL is one of the indications of UL degeneration or even malignant transformation. In our study, there is no clear relationship between the change trend of postmenopausal UL and UL degeneration. The main reason may be that the concept of health examination has not yet been popularised in China, so some women, especially postmenopausal women, do not have the habit of timely physical examination. Therefore, we cannot get the true trend of postmenopausal fibroid size change. What's more, postmenopausal women who are admitted to hospital for surgical treatment may have recently developed a hysteromyoma.
The presence or absence of UL-related symptoms is usually considered one of the indications for UL and UL surgery. However, in our study, we found that in postmenopausal women, the presence or absence of UL-related symptoms had no significant correlation with UL degeneration (OR=0.98, P=0.91). This may be related to the decline in hormone levels in postmenopausal women.UL-related symptoms (such as abnormal vaginal bleeding, abdominal pain, and frequent urination) may have a variety of causes, so it is particularly important to assess the causes of these symptoms in this population. We suggest that the presence or absence of symptoms should not be the main reason for UL surgery.
In this study we found a total of 7 predictors, namely DM, BREASTCANCER, NUMBER, size5, LDH, TG and Ca2+. Among the seven factors, a history of breast cancer is a protective factor for UL degeneration. Most breast cancers are hormone-dependent, and their occurrence and development are influenced by hormone levels in the body. Previous studies have shown that patients with UL may have an increased risk of breast cancer because UL and breast cancer have some common risk factors, such as obesity and estrogen disruption, Chuang et al[43-45] found that UL was associated with breast cancer (OR=1.20; 95% CI=1.03-1.40). However, Chiaffarino et al [46] investigated the association between the history of UL and the history of breast cancer in black women and found no obvious association (OR=0.99; 95% CI=0.90-1.08).In our study, postmenopausal women with a history of breast cancer have a reduced risk of UL degeneration with OR=0.33(P=0.099).We speculate that this result may be related to hormones, genes, genetics, etc., which needs further research.
To our knowledge, no large epidemiological study has examined the association between diabetes mellitus (DM) and uterine leiomyoma (UL) degeneration, although some studies have reported associations between diabetes and UL. Wei J et al [47] found no association with diagnosed diabetes (OR=0.9; CI=0.4-2.2), but observed an increased relative odds of 2.0 (0.4-12.6) for women taking medication for diabetes based on very small numbers. In contrast, Wise et al [48] found a reduced risk of UL in patients with diabetes in the Black Women's Health Study (OR=0.77; CL=0.60-0.98). In our study, we found diabetes to be a risk factor for postmenopausal UL degeneration with OR=2.07. In this study, we hypothesise that diabetes characterised by hyperinsulinemia may increase the risk of uterine leiomyoma (UL) degeneration, based on previous in vitro experiments [49] demonstrating its proliferative effects on uterine smooth muscle in culture. In addition, vascular dysfunction is part of the pathogenesis of diabetes, and insulin resistance and diabetes may be associated with cytotoxic effects from accompanying hyperglycaemia and other circulating cytotoxic factors [50], which may have a direct promoting effect on UL degeneration.
Lactate dehydrogenase (LDH) is an important coenzyme in glycolysis and is closely associated with malignant tumours. Serum concentrations of LDH are elevated in patients with malignant tumours of the genital tract and particularly in patients with uterine sarcomas [51,52]. In this study, we found that there was some association between LDH and the development of postmenopausal uterine fibroids (OR=0.01), but further research is needed to clarify this. Clinically, the size of fibroids is usually considered an indication for surgery, but whether this indication is appropriate for postmenopausal women needs further discussion. In this study, we found that fibroids larger than 5 cm in diameter were a risk factor for postmenopausal fibroid degeneration (OR=1.85). This may be due to oedema in the tissue during the history of fibroid degeneration, resulting in a larger fibroid volume. Interestingly, our study found that multiple myomas were a risk factor for fibroid degeneration in postmenopausal women (OR=2.86), and we speculate that this may be related to the relative decrease in blood supply associated with multiple myomas. We also found that serum triglycerides were associated with fibroids in postmenopausal women (OR=1.12), which may be related to the role of small amounts of estrogen in the fat of postmenopausal women.
Of all the laboratory indicators, we were most interested in serum calcium ion concentration. In this study, we found for the first time a certain association between serum calcium and postmenopausal uterine leiomyoma (UL) degeneration (OR=4.1, 95% cl=0.73-23). Calcium is the most abundant mineral in the human body and an essential component of bone structure. It is involved in biological processes such as cell proliferation, apoptosis, ageing and signal transduction, acting as a chemical transmitter or second messenger [53, 54]. The dynamic equilibrium formed by serum and cellular calcium provides the basic environment necessary for cells and organs to maintain their structure and function. The intestinal absorption of calcium is influenced by vitamin D, and the metabolism of vitamin D also regulates the normal physiological level of calcium [55]. Appropriate calcium supplementation is usually recommended for postmenopausal women. However, there is increasing evidence that higher calcium intake may be associated with an increased risk of death in the population [56, 57]. Some studies have suggested that abnormally high blood calcium levels caused by high calcium intake may be one of the reasons for the increased risk of death [58]. Currently, research on blood calcium levels and mortality risk is mainly focused on people with disease [59-62], while the number of studies in healthy people is small and the conclusions are inconsistent [58]. There is also epidemiological evidence that abnormal calcium levels and vitamin D deficiency are risk factors for many chronic diseases, including cancer [63]. Prostate cancer is one of the most discussed cancers in this area, but the conclusions are not consistent. Based on the study of the National Health and Nutrition Examination Survey III (NHNES III) in the United States, Gary et al. discussed in detail the effect of total blood calcium and ionic calcium levels on the risk of prostate cancer incidence and death [64, 65]. The study included 49 cases of fatal prostate cancer. The results showed that the RR value of each 0.1 mmol/L increase in total blood calcium level on the risk of fatal colorectal cancer was 1.50 (95% CI: 1.04-2.17), while the RR value of each 0. 1 mmol/L increase in ionic calcium level on the risk of colorectal cancer death was 1.50 (95% CI: 1.04-2.17), while the RR value of each 0.05 mmol/L increase in ionic calcium level was 1.72 (95% CI: 1.11-2.66) during the 96 months of follow-up.
Evidence from the Swedish AMORIS study and meta-analysis shows that serum calcium levels are negatively associated with breast cancer risk [66]. The AMORIS study included 229,674 participants with baseline data on serum calcium and albumin. During 19 years of follow-up, 10,863 cases of breast cancer were identified. The results showed that the HR of the highest group of uncorrected serum calcium levels was 0.94 (95% CI: 0.88-0.99) compared with the lowest group. The results remained almost unchanged after exposure to albumin-corrected calcium. Combined with two other prospective cohort studies [67, 68], the results of the systematic review showed that blood calcium levels had a protective effect on the risk of breast cancer, and the combined HR was 0.80 (95% CI: 0.66-0.97).
Regarding UL, few studies have focused on the relationship between serum calcium concentration, UL and its degeneration. In this study, we found that serum calcium ion concentration may have some positive correlation with UL degeneration in postmenopausal women (OR=4.01). Here we speculate that it may play a role mainly through the vitD-related pathway, but the specific mechanism needs further investigation. Furthermore, this finding may also provide us with new ideas for follow-up treatment and prevention of UL enlargement and even malignant transformation.
The present study has several strengths. First, the nomogram showed good performance in assessing the risk of uterine leiomyoma (UL) degeneration, allowing more accurate personalised clinical decision-making and monitoring. Second, to our knowledge, our study is the first to focus on predicting the risk of UL degeneration, providing a basis for personalised treatment. Finally, the nomogram was confirmed to be robust by internal bootstrap validation and showed a good positive net benefit by decision curve analysis. In addition, our prediction model has more advantages in accuracy and clinical applicability compared to the clinical experience model.
However, our study has several limitations. First, we only used internal verification methods to assess the clinical applicability of the nomograms without external validation. Second, the retrospective nature of the study inevitably introduces internal bias. Finally, the samples from our cohorts can only be considered representative of the population of Southeast China, and we aim to conduct external validation in a multicentre study.