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1Department of Gynecology, The First Affiliated Hospital of Zhengzhou University, 450000 Zhengzhou, Henan, China
*Corresponding Author(s):fcchanlp@zzu.edu.cn (Liping Han)
| History | Submitted: 25 January 2025 | Accepted: 14 March 2025 | Published: 15 September 2025 |
| Copyright: | ©2025 The Author(s). Published by MRE Press. |
The co-occurrence of adenomyosis and endometrial cancer (EC) has garnered increasing attention due to its potential impact on tumor progression and patient outcomes. Adenomyosis, characterized by ectopic endometrial tissue within the myometrium, creates a unique inflammatory and hormonal microenvironment that may influence endometrial tumor biology. This review synthesizes findings from studies conducted in the last decade, focusing on tumor stage, histopathological characteristics, and prognostic outcomes in patients with coexisting adenomyosis and EC. Evidence suggests that adenomyosis is associated with favorable tumor characteristics, such as reduced deep myometrial invasion and lymphovascular space invasion and may correlate with improved survival outcomes. However, conflicting findings highlight the need for further research to elucidate these interactions and their underlying mechanisms.
Cite this article
Vinita Shiwali, Xintong Cai, Liping Han. Adenomyosis in endometrial cancer: protective factor or prognostic marker? A narrative review.European Journal of Gynaecological Oncology,2025,46(9):11-16 DOI:10.22514/ejgo.2025.115
Endometrial cancer (EC), the most common gynecological malignancy worldwide and has an increasing incidence due to factors such as obesity, hormonal changes and demographic trends [1, 2]. Although EC predominantly affects postmenopausal women, with 75% of cases occurring in individuals over 50, it is increasingly diagnosed in younger women aged 30–49 due to lifestyle and metabolic factors [3]. In 2020, an estimated 417,367 new cases were reported globally, with the United States alone projecting 66,000 new cases and 13,000 deaths in 2023 [4]. Projections suggest new annual cases in the U.S. may rise to 122,000 by 2030 [2]. Obesity, a modifiable risk factor, accounts for nearly 50% of EC cases and exacerbates risk through chronic estrogen exposure, inflammation, insulin resistance and oxidative stress [5]. Other contributing factors include hormonal imbalances, type2 diabetes mellitus, hypertension, early menarche, late menopause, nulliparity, hormone replacement therapy without progesterone and tamoxifen use, while protective factors include breastfeeding and delayed childbirth [6]. EC is classified into two subtypes: Type I, hormone-driven cancers with favorable outcomes, and Type II, aggressive, poorly differentiated cancers with poor prognosis [7]. Diagnosis relies on transvaginal ultrasound (TVUS), with hysteroscopy-guided biopsy as the gold standard and imaging modalities like Magnetic Resonance Imaging (MRI) and Positron Emission Tomography-Computed Tomography (PET-CT) aiding in staging [6]. Treatment primarily involves total hysterectomy with bilateral salpingo-oophorectomy, with minimally invasive surgery preferred for early-stage disease. Adjuvant therapy is risk-based, ranging from no further treatment for low-risk patients to combined radiotherapy and chemotherapy for high-intermediate-risk patients [4, 8]. Fertility-preserving options, such as progestin-based therapies, are available for young patients with early-stage, low-grade tumors [2].
Adenomyosis is a gynecological disorder where endometrial tissue invades the myometrium, causing uterine enlargement, abnormal uterine bleeding (AUB), pelvic pain and infertility [9]. It can be diffuse or focal, with a prevalence of 12–58% among reproductive-age women [10]. The exact cause is unclear but may involve hormonal imbalances, uterine trauma, or repeated injuries triggering abnormal healing [11]. Risk factors include multiple pregnancies, obesity and surgeries like cesarean sections [12].
Diagnosis has shifted from hysterectomy to non-invasive methods like transvaginal ultrasonography (TVUS) and MRI, with biomarkers like Cancer Antigen (CA)125 aiding in management [13]. Treatment options include hormonal therapies, fertility-sparing surgeries and minimally invasive procedures, while hysterectomy remains definitive for those not preserving fertility [14]. Hysterectomy remains the definitive treatment for women who do not wish to preserve fertility [12].
Adenomyosis characterized by endometrial tissue invasion into the myometrium, is frequently observed in endometrial cancer (EC) patients [1]. Its fibrotic stroma and altered cytokine profile, including elevated levels of Transforming Growth Factor (TGF)-β and Interleukin (IL)-10, create a microenvironment that suppresses tumor invasion and progression [15, 16]. Additionally, adenomyosis may act as a physical barrier, reducing cancer cell infiltration into the myometrium [17]. The condition’s symptoms such as dysmenorrhea and abnormal bleeding, often lead to earlier detection of EC, facilitating timely diagnosis and intervention [18].
Adenomyosis has been associated with less aggressive tumor features in EC, including reduced deep myometrial invasion (DMI), lymphovascular space invasion (LVSI) and lower tumor grades [15]. Patients with adenomyosis are often diagnosed at earlier stages, which correlates with improved overall survival (OS) and disease-free survival (DFS) [4]. However, conflicting evidence exists, necessitating further research to validate these findings [19].
Adenomyosis and EC share molecular abnormalities, including dysregulated Wnt/β-catenin signaling, epithelial-mesenchymal transition (EMT) and progesterone resistance [20]. Endometrial stem cell dysfunction is central to both conditions, driving abnormal tissue proliferation and invasion [21]. Mesenchymal stem cells (MSCs) in adenomyosis exhibit altered exosomal miRNA profiles, which may inhibit EMT and metastasis in EC cells, potentially explaining its protective role [22].
Patients with adenomyosis demonstrate an immune microenvironment enriched in antitumor cytokines such as interferon-γ and tumor necrosis factor-α, with reduced pro-tumor cytokines [23, 24]. This immunological shift impairs cancer cell growth and invasion. Additionally, the increased vascular endothelial growth factor (VEGF) levels observed in both conditions contribute to angiogenesis but may also regulate tumor growth differently in adenomyosis-associated EC [25].
Adenomyosis carries the rare risk of malignant transformation into endometrial carcinoma arising in adenomyosis (EC-AIA) [19]. This phenomenon is characterized by cancerous changes within adenomyotic tissue, resulting in aggressive tumor behavior and increased metastatic potential [26]. The proximity of adenomyotic tissue to vascular and lymphatic structures may facilitate dissemination, though the exact mechanisms remain unclear [15].
Estrogen plays a pivotal role in both adenomyosis and EC by upregulating annexin A2 (ANXA2), a protein involved in EMT and angiogenesis [15]. ANXA2 enhances the invasive properties of adenomyotic and cancerous tissues, correlating with higher International Federation of Gynecology and Obstetrics (FIGO) stages, deeper myometrial invasion and lymph node metastasis in EC [27]. Its contribution to tumor growth and dissemination underscores its significance in the disease’s progression.
Both conditions share genetic mutations in Kirsten Rat Sarcoma Viral Oncogene Homolog (KRAS), Phosphatidylinositol-4,5-Bisphosphate 3-Kinase Catalytic Subunit Alpha (PIK3CA) and Protein Phosphatase 2 Regulatory Subunit A Alpha (PPP2R1A), which regulate cell proliferation, survival and invasion [28, 29]. These mutations indicate overlapping pathways in their pathogenesis. Progesterone resistance, common to both, disrupts hormonal balance, allowing uncontrolled proliferation of adenomyotic and cancerous tissues [30].
Pro-inflammatory cytokines, reactive oxygen species (ROS), and angiogenic factors drive a pro-inflammatory microenvironment in both conditions, promoting tissue damage, repair and proliferation [31, 32]. Oxidative stress and DNA damage further contribute to the progression of adenomyosis and EC [15].
The coexistence of adenomyosis in patients with endometrial cancer (EC) has been a topic of increasing interest, given its potential impact on tumor characteristics and patient outcomes. While some studies report favorable prognostic implications of adenomyosis, others suggest no significant impact on survival or tumor progression. This literature review summarizes findings from systematic reviews, meta-analyses and retrospective studies to provide a comprehensive understanding of this association.
Several studies have investigated the prognostic impact of adenomyosis on survival outcomes in endometrial cancer (EC) patients, yielding mixed results. Raimondo et al. [18] (2021) conducted a systematic review and meta-analysis, reporting that adenomyosis was associated with significantly reduced mortality risks. The pooled hazard ratio (HR) for overall survival (OS) was 0.533 (95% Confidence Interval (CI): 0.329–0.864), and for disease-free survival (DFS), it was 0.536 (95% CI: 0.334–0.859) in univariate analysis. However, these associations were not statistically significant after multivariate adjustment (DFS HR: 0.875, 95% CI: 0.331–2.315). Similarly, Casadio et al. [33] (2021) noted no significant differences in clinical characteristics between EC patients with and without adenomyosis, except for a lower prevalence of nulliparity in the adenomyosis group (pooled Odds Ratio (OR): 0.60, 95% CI: 0.41–0.87, p = 0.007). Contrarily, Buyuksahin et al. [1] (2023) found no significant impact of adenomyosis on OS or DFS, suggesting no effect on overall prognosis.
Boonlak et al. [34] (2019) reported that EC patients without adenomyosis had higher rates of deep myometrial invasion (52.8% vs. 39.4%, p = 0.02) and lymphovascular space invasion (53.2% vs.38.6%, p = 0.01). However, no significant differences were found in five-year OS (HR: 0.81; 95% CI: 0.43–1.53) or recurrence-free survival (HR: 1.47; 95% CI: 0.88–2.44) between the groups.
Several studies suggest that adenomyosis may confer a protective effect against aggressive tumor characteristics in EC. Habiba et al. [35] (2018) proposed that the favorable outcomes observed in adenomyosis-associated EC could be attributed to earlier detection. Musa et al. [36] (2012) demonstrated that lymphovascular space invasion (LVSI) predicted lymph node metastasis in EC patients without adenomyosis but not in those with adenomyosis.
Studies by Hertlein et al. [37] (2017) and Gizzo et al. [38] (2016) associated adenomyosis with earlier-stage disease, lower tumor grades and improved five-year survival rates (95% vs. 82%). Wang et al. [39] (2023) reported improved OS (HR: 0.62, 95% CI: 0.50–0.79) and DFS (HR: 0.60, 95% CI: 0.44–0.82) in patients with adenomyosis. Similarly, Matsuo et al. [40] (2014) and Hermens et al. [41] (2022) identified survival benefits, with HRs of 0.42 (95% CI: 0.23–0.78) for OS and 0.25–0.70 for DFS. Celik et al. [42] (2022) found a 52% reduced risk of mortality in patients with adenomyosis (HR: 0.48, 95% CI: 0.29–0.78), while Aslan et al. [43] (2020) observed significantly improved five-year DFS in the adenomyosis group (HR: 0.34, 95% CI: 0.12–0.96). Raffone et al. [44] (2022) further highlighted a protective role for adenomyosis, showing reduced risks of advanced tumor stage (Relative Risk (RR): 0.60, p = 0.005), high tumor grade (RR: 0.55, p < 0.00001) and deep myometrial invasion (RR: 0.65, p = 0.001).
Adenomyosis appears to influence the pathological features of EC. Hirai et al. [45] (1999) reported reduced odds of deep myometrial invasion in adenomyosis patients (OR: 0.37, 95% CI: 0.21–0.65). Zouzoulas et al. [46] (2018) observed a lower likelihood of high-grade tumors in adenomyosis-associated EC, though without statistical significance (OR: 0.57, 95% CI: 0.30–1.07). Zhang et al. [47] (2018) reported that adenomyosis in endometrial cancer patients was linked to earlier-stage disease, lower-grade tumors, and reduced myometrial invasion and lymph node metastasis. It also correlated with improved 5-year survival rates (92.1% vs. 84.1%). Mao et al. [48] (2017) reported that patients with malignant transformation of adenomyosis tended to be younger. Min et al. [49] (2020) through a meta-analysis, concluded that adenomyosis is associated with favorable tumor characteristics, supporting its protective role.
Despite these findings, some studies report conflicting results. Machida et al. [50] (2017) observed an increased HR for reduced DFS (HR: 2.87, 95% CI: 1.44–5.70, p = 0.031) in adenomyosis patients, suggesting more aggressive disease in some cases. Chao et al. [51] (2020) similarly found a higher HR for five-year OS (HR: 3.07, 95% CI: 0.91–10.3), indicating worse outcomes in certain cohorts.
Şimşek et al. [52] (2023) and Yilmaz et al. [53] (2022) found no significant differences in survival or recurrence rates between adenomyosis and non-adenomyosis groups. Yetimalar et al. [54] (2022) noted improved five-year DFS in adenomyosis patients (HR: 0.17, 95% CI: 0.03–1.25), but Taneichi et al. [55] (2014) and Koshiyama et al. [56] (2004) reported only trends favoring survival benefits without statistical significance.
Aydin et al. [57] (2018) observed higher HRs for OS (HR 1.60, 95% CI: 0.49–5.26) and DFS (HR 1.54, 95% CI: 0.56–4.27) in the adenomyosis group, suggesting no survival benefit. Johnatty et al. [58] (2020) described adenomyosis as an independent risk and prognostic factor, but their findings lacked statistical significance for OS (HR 0.77, 95% CI: 0.46–1.28) and DFS (HR 0.52, 95% CI: 0.25–1.07).
Adenomyosis has emerged as a condition of interest in endometrial cancer (EC) research due to its potential association with favorable clinical outcomes. Studies suggest that patients with adenomyosis often experience reduced risks of deep myometrial invasion (DMI), lymphovascular space invasion (LVSI) and high-grade tumors. Moreover, they are frequently diagnosed at earlier stages of EC, which contributes to better overall survival (OS) and disease-free survival (DFS). However, the evidence is not unanimous, with conflicting findings necessitating further investigation to confirm these observations.
The protective role of adenomyosis may be attributed to its unique influence on the tumor microenvironment. The ectopic endometrial glands and stroma embedded within the hypertrophic myometrium are believed to act as a physical barrier, restricting tumor invasion. Furthermore, the inflammatory and hormonal changes characteristic of adenomyosis might suppress tumor progression. Although these mechanisms are intriguing, they remain speculative, requiring additional studies to elucidate their impact on tumor biology.
Adenomyosis frequently coexists with endometriosis in patients with EC, with all three conditions sharing a common foundation in stem cell dysregulation [59]. Abnormal proliferation and differentiation of endometrial and mesenchymal stem cells are thought to drive ectopic tissue growth, chronic inflammation and hormonal imbalances, forming a shared pathological framework [60]. In adenomyosis and endometriosis, these stem cells promote tissue invasion, angiogenesis and immune evasion. Similarly, in EC, stem-like cells are implicated in tumor initiation, metastasis and therapy resistance [61]. This overlapping reliance on stem cell dysfunction offers a plausible explanation for the protective association observed between adenomyosis and EC.
Despite promising insights, research on adenomyosis in EC faces significant limitations and challenges. Variability in diagnostic criteria, small sample sizes, and retrospective study designs hinder the reliability of existing evidence. While meta-analyses have highlighted a possible protective effect, the lack of standardized methodologies and inadequate control for confounding factors complicate the interpretation of findings. These limitations underscore the need for more rigorous and comprehensive investigations.
To advance understanding, future research should prioritize multicenter, prospective studies with larger cohorts and uniform diagnostic criteria. Exploring the biological mechanisms underpinning adenomyosis, particularly its effects on immune modulation and stromal interactions, could provide valuable insights. Furthermore, identifying the precise role of stem cell dysregulation in the pathophysiology of adenomyosis, endometriosis and EC may open avenues for innovative therapeutic strategies.
In conclusion, while adenomyosis shows potential as a protective factor in EC, its role remains incompletely understood. Addressing current research gaps through systematic studies is essential to establish adenomyosis as a reliable prognostic marker and uncover its therapeutic implications. By exploring the interconnected mechanisms of adenomyosis, endometriosis and EC, future work may pave the way for improved patient outcomes and targeted management strategies.
EC, Endometrial cancer; LVSI, Lymphovascular space invasion; AUB, Abnormal uterine bleeding; DMI, Deep Myometrial Invasion; TVUS, Tras vaginal ultrasound; MRI, Magnatic Resonance Imaging; PET-CT, Positron Emission Tomography-Computed Tomography; CA125, Cancer Antigen 125; KRAS, Kirsten rat sarcoma viral oncogene homolog; MSC, Mesenchymal stem cells; EC-AIA, Endometrial cancer arising-in adenomyosis; ANXA2, Annexin A2; EMT, Epithelial-mesenchymal transition; VEGF, Vascular endothelial growth factor; ROS, Reactive oxygen species; PIK3CA, Phosphatidylinositol-4,5-Bisphosphate 3-Kinase Catalytic Subunit Alpha; OS, Overall Survival; DFS, Disease Free Survival; HR, Hazard Ratio; CI, Confidence Interval; RR, Relative Risk; FIGO, International Federation of Gynecology and Obstetrics; PPP2R1A, Protein Phosphatase 2 Regulatory Subunit A Alpha; OR, Odds Ratio.
This review article is based on a comprehensive analysis of previously published literature. All data and materials used in the preparation of this manuscript are derived from publicly available sources, including published articles, databases, and other referenced materials cited in the manuscript. No new data were generated or analyzed for this study. All relevant references have been included to ensure transparency and reproducibility.
VS—responsible for conceptualization; designed the review framework; conducted the literature search; analysis; interpretation of findings and manuscript writing. XTC—responsible for reviewing and editing. LPH—responsible for supervising and reviewing the manuscript. All authors read and approved the final manuscript.
Not applicable.
Our gratitude to all participants in the study for their invaluable contribution.
This research was supported by the Natural Science Foundation of Henan Province (242300421278).
The authors declare no conflict of interest.