Microscale Endometrial Sampling Biopsy in Detecting Endometrial Cancer and Atypical Hyperplasia: A Comparative Study with Hysteroscopic Biopsy
Endometrial cancer remains one of the most prevalent gynecologic malignancies, with rising global incidence rates. Despite advancements in diagnostic techniques, a cost-effective and minimally invasive screening method for high-risk populations remains elusive. Traditional methods such as hysteroscopy and dilation and curettage (D&C) are invasive, require hospitalization, and incur high costs. This study evaluates the efficacy of microscale endometrial sampling biopsy (MESB) using a novel device, the SAP-1 sampler, in detecting endometrial cancer and atypical hyperplasia, comparing its performance and cost to hysteroscopic biopsy, the current gold standard.
Methodology
Study Design and Population
A prospective comparative study enrolled 1,551 women at high risk for endometrial lesions between November 2017 and August 2018. Inclusion criteria encompassed abnormal uterine bleeding, ultrasound findings of endometrial thickening (≥5 mm in postmenopausal women), or follow-up after progesterone treatment for endometrial lesions. Exclusions included cervical cancer, acute pelvic infections, recent pregnancy, or use of a levonorgestrel intrauterine system.
Sampling Techniques
Microscale Endometrial Sampling Biopsy (MESB):
The SAP-1 device, a 2.8-mm diameter polypropylene sampler with a serrated loop, was inserted into the uterine cavity under anesthesia. The loop, designed to match the uterine contour, collected tissue via 360° rotation, ensuring contact with all endometrial surfaces. Specimens were fixed, embedded using a specialized microsample processor, and sectioned for hematoxylin-eosin staining.
Hysteroscopic Biopsy:
Following MESB, hysteroscopy (Olympus, Japan) was performed under direct visualization. Biopsies were taken from suspicious areas, fixed in formalin, and processed conventionally.
Evaluation Criteria
- Specimen Adequacy: Defined by visible hysteroscopic scratch marks, presence of ≥5 glandular structures, and diagnostic clarity.
- Pathological Diagnosis: Classified into four categories: endometrial cancer, atypical hyperplasia, benign/normal endometrium, and intrauterine lesions (polyps, fibroids).
- Statistical Analysis: Diagnostic consistency was assessed via Cohen’s kappa. Sensitivity, specificity, and predictive values were calculated using hysteroscopic biopsy as the reference. Costs for both procedures were compared, excluding hospitalization fees for hysteroscopy.
Results
Specimen Adequacy and Influencing Factors
MESB achieved an adequacy rate of 81.2% (1,260/1,551). Factors influencing adequacy included:
- Menopausal Status: Adequacy was significantly higher in premenopausal (89.6%) vs. postmenopausal women (59.8%; P <0.001).
- Endometrial Thickness: ROC analysis identified 6.5 mm as the optimal cutoff (AUC: 0.722; sensitivity 71.4%, specificity 66.7%).
- Lesion Type: Adequacy was higher in malignant lesions (97.1%) vs. benign conditions (79.3%; P <0.001).
Multivariate analysis confirmed menopausal status (OR: 3.16), age (OR: 1.029 per year), and endometrial thickness (OR: 0.885 per mm) as independent predictors.
Diagnostic Performance
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Consistency with Hysteroscopy:
- For distinguishing malignant (cancer, atypical hyperplasia) vs. benign lesions, agreement was excellent (kappa = 0.950; 95% CI: 0.925–0.975).
- Subgroup analysis showed lower agreement for specific benign subtypes (kappa = 0.248), attributed to challenges in sampling structural anomalies like polyps.
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Sensitivity and Specificity:
- Endometrial Cancer: Sensitivity 91.7% (111/121), specificity 100%, PPV 100%, NPV 99.3%.
- Atypical Hyperplasia: Sensitivity 82.0% (41/50), specificity 100%, PPV 100%, NPV 99.4%.
Cost Analysis
MESB costs were 22.1% of hysteroscopic biopsy ($44.49 vs. $201.34), driven by outpatient applicability and reduced procedural fees.
Discussion
Clinical Utility of MESB
MESB demonstrated high diagnostic accuracy for malignant lesions, offering a viable alternative to hysteroscopy in screening contexts. Its minimally invasive design minimizes patient discomfort and eliminates the need for cervical dilation. The SAP-1 device’s loop structure ensures comprehensive endometrial sampling, critical for detecting focal malignancies.
Limitations and Considerations
- Postmenopausal and Thin Endometria: Lower adequacy rates in these groups suggest supplemental imaging or repeat sampling may be necessary.
- Intrauterine Lesions: MESB’s poor performance in diagnosing polyps or fibroids underscores the need for hysteroscopy in cases of structural anomalies.
- Operator Dependency: Consistent technique is crucial to avoid inadequate sampling, particularly in atrophic endometria.
Comparative Advantages
MESB’s cost-effectiveness and outpatient feasibility position it as a first-line screening tool, reducing the burden on healthcare systems. For high-risk women, it could triage patients requiring hysteroscopy, optimizing resource allocation.
Future Directions
Further studies should validate MESB in diverse populations, including asymptomatic high-risk groups. Integration with molecular biomarkers may enhance its diagnostic precision, particularly for precancerous lesions.
Conclusion
Microscale endometrial sampling biopsy represents a transformative advancement in endometrial cancer screening. With high diagnostic accuracy, minimal invasiveness, and significant cost savings, MESB addresses critical gaps in current clinical practice. While hysteroscopy remains indispensable for structural evaluations, MESB offers a scalable solution for early detection in high-risk populations, ultimately improving patient outcomes and healthcare efficiency.
DOI: 10.1097/CM9.0000000000001109
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