Clinicopathologic evaluation of uterine smooth muscle tumors of uncertain malignant potential (STUMP): A single center experience

A Review and Follow-Up of Uterine Smooth Muscle Tumours of Uncertain Malignant Potential (STUMP): A Case Series and Literature Review

OBJECTIVES

to analyse the clinical-pathological characteristics, treatment, and evolution of uterine smooth muscle tumours with uncertain malignant potential (STUMP) diagnosed in the Salamanca University Hospital with the implementation of the 2014 WHO criteria.

MATERIALS AND METHODS

a retrospective descriptive study of patients diagnosed with STUMP from January 2015 to March 2023 at the Salamanca University Hospital. Demographic data, preoperative clinical data, treatment, complications, therapeutic results, anatomopathological findings and recurrence time were obtained.

RESULTS

a total of four patients were identified and included in the study. The mean age at diagnosis was 48 years (range 36-67). The surgical indications were abnormal uterine bleeding, compressive symptoms, and the growth of a pelvic mass suspected to be a degenerated myoma from the residual cervix after a subtotal hysterectomy 6 years earlier. In all cases, a laparotomic procedure was performed. A total hysterectomy, sub-total hysterectomy, and the excision of the cervix with STUMP localization were accomplished in two, one, and one patient, respectively. The mean diameter of the tumour pieces was 13 cm (range 8-17 cm), with a mean volume of 816 cc (range 234-1467 cc). The mean follow-up was 47 months, with no recurrence to date.

CONCLUSIONS

STUMPs are a heterogeneous group of tumours with a difficult-to-predict clinical evolution. In most cases, their diagnosis is histological after performing surgery for suspected leiomyoma. Due to their low incidence, there are no specific guidelines for their treatment and control. However, considering their potential risk of recurrence and metastasis, it is advisable to maintain six-monthly controls for 5 years and then annual controls for 5 years more.

Clinical and Histopathological Predictors of Recurrence in Uterine Smooth Muscle Tumor of Uncertain Malignant Potential (STUMP): A Multicenter Retrospective Cohort Study of Tertiary Centers

BACKGROUND

The term uterine smooth muscle tumor of uncertain malignant potential (STUMP) indicates a rare, equivocal entity between benign leiomyomas and leiomyosarcomas. In the present study, we evaluated a comprehensive range of clinical, surgical, and pathological features in a large multicenter series of patients with STUMP to identify risk factors for recurrence.

METHODS

This is a retrospective study performed by collecting consecutive cases diagnosed between January 2000 and December 2020 in five tertiary centers. Associations between STUMP recurrence and clinicopathological characteristics as well as surgical treatment modality were investigated.

RESULTS

Eighty-seven patients affected by STUMP were considered. Of them, 18 cases (20.7%) recurred: 11 as leiomyosarcoma (LMS) and 7 as STUMP. The mean time to recurrence was 79 months. We found that fragmentation/morcellation, epithelioid features, high mitotic count, Ki-67 value > 20%, progesterone receptor (PR) < 83%, and p16 diffuse expression were associated with higher risk of recurrence and shorter recurrence-free survival (RFS). Furthermore, morcellation/fragmentation and mitotic count remained independent risk factors for recurrence and shorter RFS after multivariate analysis, while the presence of epithelioid features was an independent risk factor for recurrence only.

CONCLUSIONS

Our results suggest that morcellation is associated with risk of recurrence and shorter RFS, thus it should be avoided if a STUMP is suspected preoperatively. Epithelioid features, high proliferation activity, low PR expression, and diffuse p16 expression are also unfavorable prognostic factors, so patients presenting these features should be closely followed up.

Recurrence of Uterine Smooth Muscle Tumor of Uncertain Malignant Potential: A Systematic Review of the Literature

Background: This study aimed to systematically review the existing literature on uterine smooth muscle tumor of uncertain malignant potential (STUMP) to provide information about characteristics and outcomes of patients and the risk factors for recurrence over a period of 60 years (1960−2021). Methods: According to PRISMA guidelines, we searched for "uterine smooth muscle tumor of uncertain malignant potential" in PubMed (all fields) and Scopus (Title/Abstract/Keywords) databases (accessed on 1 January 2022). Relevant articles were obtained in full-text format and screened for additional references. The only filter used was the English language. Studies including full case description of patients with histopathological diagnosis of STUMP in accordance with Stanford criteria were included. Results: Thirty-four studies, including 189 cases, were included. The median age was 43 years, and in 21.5% of cases there was a recurrence of the disease. Bivariate analysis showed a significant association between use of morcellation without bag and risk of recurrence (p = 0.001). Unprotected morcellation during demolitive or conservative surgery was independently associated with a higher risk of disease recurrence with a relative risk of 2.94 (p < 0.001). A significant progressive decrease in the recurrence rate was observed over time (r = −0.671, p = 0.008). The percentage of patients who underwent surgery followed by in-bag protected morcellation significantly increased after the publication of the U.S. Food and Drug Administration alert about the risk linked to this procedure (p = 0.01). Conclusions: Unprotected morcellation of the lesion is associated with the relapse of the disease. However, this clinical condition showed a drastic decrease over time. This could likely be due to the increased awareness by surgeons of the importance of customizing surgical treatment.

Risk of Recurrence in Uterine Leiomyoma with Bizarre Nuclei: a Systematic Review and Meta-Analysis

Objective Leiomyoma with bizarre nuclei (LBN) is a variant of uterine leiomyoma, which has replaced the previous category of “atypical leiomyoma” and must be distinguished from smooth muscle tumors of uncertain malignant potential (STUMP). However, previously published series of “atypical leiomyoma” might have included both LBN and STUMP, due to the lack of strict diagnostic criteria. Based on such hypothesis, we aimed to define the risk of recurrence in LBN.

Study Design A systematic review and meta-analysis was performed by searching 4 electronic databases for all studies assessing the outcome of patients with “atypical leiomyoma” or LBN. The pooled absolute risk of recurrence was calculated. The included studies were subdivided into two subgroups based on the criteria used: “LBN + STUMP” or “LBN-only”.

Results Twelve studies with 433 patients were included. The pooled risk of recurrence was 5.5% overall. The funnel plot showed two cluster of studies which superimposed to the two subgroups. In the LBN + STUMP cluster/subgroup, the pooled risk of recurrence was 7.7%. In the LBN-only cluster/subgroup, the pooled risk of recurrence was 1.9%. Statistical heterogeneity was null in all analyses.

Conclusion Our results show a risk of recurrence of 1.9% for LBN; higher recurrence rates in older studies are likely due to the inclusion of STUMPs.

p53, p16 and ki67 as immunohistochemical prognostic markers in uterine smooth muscle tumors of uncertain malignant potential (STUMP)

The risk stratification in gynecologic smooth muscle tumors of uncertain malignant potential (STUMP) is a crucial issue, but at present there are no validated prognostic markers. We aimed to assess p53, p16 and ki67 as immunohistochemical prognostic markers in STUMP through a systematic review and meta-analysis. Electronic databases were searched from their inception to July 2020. All studies assessing p53, p16 and/or ki67 immunohistochemistry in gynecologic STUMP series were included. Immunohistochemical patterns were categorized as "abnormal" vs "wild-type" for p53, "diffuse" vs "focal/negative" for p16, ≥ 10% vs 10% for ki67. The prognostic value for recurrence was assessed through Cox regression analysis; a p-value 0.05 was considered significant. Markers that resulted significant were assessed for prognostic accuracy with calculation of area under the curve (AUC) and post-test probability of recurrence. Seven studies with 171 patients were included. Significant association with disease-free survival was found for p53 (p 0.0001) and p16 (p 0.0001), but not for ki67 (p = 0.911). p53 showed sensitivity= 83%, specificity= 86%, AUC= 0.89, and post-test recurrence probabilities of 54% and 7% in the case of abnormal and wild-type expression, respectively. p16 showed sensitivity= 84%, specificity= 88%, AUC= 0.91 and post-test recurrence probabilities of 56% and 7% in the case of diffuse and focal/negative expression, respectively. In conclusion, p53 and p16 might be useful in the risk assessment of STUMP, despite not being suitable as stand-alone prognostic markers.

Clinical and reproductive outcomes of uterine smooth muscle tumor of uncertain malignant potential: a single-center retrospective study

OBJECTIVE

To evaluate the clinical outcomes, histopathological features, and obstetric and oncological outcomes of uterine smooth muscle tumor of uncertain malignant potential (STUMP).

METHODS

We conducted a single-center, database review of patients with STUMP between January 2001 and December 2015. We investigated the clinical, operative, histopathologic, recurrence, and fertility outcomes of the included cases.

RESULTS

Nineteen patients with STUMP were studied. Three were reclassified as sarcoma after slide review, and 16 patients were finally included in the study. The mean age was 45 years. Ki-67 expression was ≥10% in 25.0% of cases and 30% in the only recurrent case. Recurrence occurred 52 months after a diagnosis of STUMP in a 56-year-old female patient who underwent hysterectomy. Two of six patients who underwent myomectomy had fertility requirements, and both successfully delivered babies without recurrence. Recurrence was not related to mitosis, degree of atypia, or necrosis. There was also no relationship between type of surgery or surgical approach and recurrence.

CONCLUSIONS

Patients with STUMP warrant a pathological review process in centers with experience. Fertility-preservation is worth attempting, but young patients must be followed-up closely. Ki-67 might be a valuable marker predicting recurrence.

Stanford parameters stratify the risk of recurrence in gynecologic smooth muscle tumors of uncertain malignant potential

Smooth muscle tumor of uncertain malignant potential (STUMP) is an ill-defined category of neoplasms, which represent a diagnostic challenge. We aimed to assess whether the Stanford parameters, that is, high mitotic index (≥10/10HPF), significant atypia (moderate-to-severe), and coagulative tumor cell necrosis (CTCN), even when focal or ambiguous, may be used to stratify the risk of recurrence in gynecological smooth muscle tumor of uncertain malignant potential (STUMP). Electronic databases were searched from their inception to October 2019. All studies assessing the Stanford parameters in gynecological STUMP series were included. STUMPs were subdivided according to the presence of the three Stanford parameters: high mitotic index, significant atypia, and CTCN. A Kaplan-Meier survival analysis was performed for recurrence-free survival; hazard ratio (HR) was calculated in each category. Fourteen studies with 219 STUMPs were included. In 15.5% of cases, none of the three Stanford parameters were present, with a recurrence risk of 5.9%; 2.7% of cases showed high mitotic index alone, with a recurrence risk of 0% (HR = not calculable); 43.8% of cases showed significant atypia alone, with a recurrence risk of 18.7% (HR = 3.3; p = 0.012); 26.5% of cases showed CTCN alone, with a recurrence risk of 17.2% (HR = 3.1; p = 0.029); and 11.4% of cases showed at least two Stanford parameters, with a recurrence risk of 32% (HR = 7.5; p = 0.003). Stanford parameters may stratify the risk of recurrence of STUMP. Significant atypia and CTCN, but not high mitotic index, may be stand-alone risk factors for recurrence in STUMP. The presence of at least two Stanford parameters, even if equivocal (e.g., uncertain or focal CTCN, focal significant atypia, mitotic index around 10/10HPF), might still be enough to support a diagnosis of leiomyosarcoma. Further studies are necessary in this field.

Prognostic significance of atypical mitotic figures in smooth muscle tumors of uncertain malignant potential (STUMP) of the uterus and uterine adnexa

We aimed to assess whether the presence of atypical mitotic figures (AMF) in smooth muscle tumors of uncertain malignant potential (STUMP) of the uterus and uterine adnexa is associated with increased risk of recurrence, and the association of AMF with the Stanford criteria, that is, significant cytologic atypia, mitotic index ≥ 10/10HPF, and coagulative tumor cell necrosis (CTCN). A systematic review was performed to identify all studies reporting the presence of AMF and oncologic outcomes in STUMP series. Fisher's exact test was used to assess the association of AMF with the three Stanford parameters. Kaplan-Meier and Cox regression survival analyses with hazard ratio (HR) calculation were performed to assess the association between AMF and STUMP recurrence. A p-value < 0.05 was considered significant. Five studies with 80 STUMPs were included, out of which 23.8% had AMF. AMF were significantly associated with the presence of significant atypia (p = 0.023), but not with the presence of a mitotic index ≥ 10/10HPF (p = 0.769), CTCN (p = 1), or more than one Stanford parameter (p = 0.171). AMF was not significantly associated with the risk of STUMP recurrence at both univariate (HR = 0.366; p = 0.188) and multivariate analyses (HR = 0.528; p = 0.463). In STUMP of the uterus and uterine adnexa, AMF are more common in the case of significant cytologic atypia, but do not seem to increase the risk of recurrence. Further studies are necessary in this regard.

Secondary cytoreductive surgery in recurrent uterine leiomyosarcoma: a multi-institutional study

INTRODUCTION

Uterine leiomyosarcoma (uLMS) represents a rare gynecological malignancy with high incidence of recurrence. Evidence in literature about the management of recurrent uLMS is limited, and the role of secondary cytoreduction has been evaluated in small and heterogeneous populations. The objective of this study is to assess the prognostic role of secondary cytoreductive surgery and its related complications in a large and homogeneous group of patients.

METHODS

All consecutive patients who underwent surgery for recurrent uLMS between 01/2010-01/2018 at four Italian tertiary referral centers, were included. Relevant demographic and clinico-pathologic data were retrieved. Survival curves were estimated by Kaplan-Meier method and compared by log-rank test. Cox-proportional hazard model was used to assess the effect of the most predictive prognostic variables.

RESULTS

38 patients with recurrent uLMS were treated with secondary cytoreductive surgery in the study period. Recurrence presented as isolated disease in 17 (44.7%) cases. Bowel, bladder and upper abdominal surgery was performed in 50.0%, 18.4% and 28.9% of the cases, respectively. No residual tumor was the final surgical result in 35 (92.1%) patients. Median hospital stay was 7 days (range, 1-24). No women had major intra-operative and 4 (33.3%) had major post-operative complications. No patient died within 30-days from the secondary cytoreduction. Median time to the first cycle of adjuvant chemotherapy was 41-days (range, 29-78). Median recurrence-free survival was 16.0months (95%CI,11.6 to 26.1). 5-year overall survival (OS) was 76% (95%CI,53 to 89%). Time to first recurrence >12months significantly affected OS (p=0.04).

DISCUSSION

Secondary cytoreduction in recurrent uLMS often requires complex and extensive surgical procedures. Referral to tertiary centers guarantees low peri-operative morbidity, short length of hospitalization and median time to chemotherapy within the standard of care. Therefore, secondary cytoreduction to no residual disease is an option that may be considered in recurrent uLMS, especially in patients with time to first recurrence >12months.