Endometrial Cancer: An Overview of Introduction, Types, Pathogenesis,Lab Diagnosis, Treatment, Prevention, and Keynotes

Introduction

Endometrial cancer is a malignancy that originates in the endometrium, the inner epithelial lining of the uterus. It stands as the most common gynecological cancer in developed countries and primarily affects postmenopausal women, with a median age of diagnosis around 62–63 years. The most classic clinical presentation is abnormal postmenopausal uterine bleeding, which often allows for detection at an early, highly curable stage.

Types of Endometrial Cancer

Historically and pathologically, endometrial cancer is classified into two distinct histological groups, though modern medicine relies heavily on a newer four-tiered molecular classification system.

1. Traditional Histological Categories (Bokhman Classification)

• Type I (Endometrioid): Accounts for roughly 80% of cases. It is estrogen-dependent, arises from atypical endometrial hyperplasia, consists of low-grade cells, and has a highly favorable prognosis.
• Type II (Non-endometrioid): Accounts for 10–20% of cases. It is estrogen-independent, arises from the atrophic endometrium, consists of high-grade cells, and includes aggressive subtypes such as serous carcinoma, clear cell carcinoma, and carcinosarcoma. It carries a high risk of relapse and poor survival rates.

2. Modern Molecular Categories (TCGA Subtypes)

The Cancer Genome Atlas (TCGA) groups tumors by genetic drivers to better guide targeted therapies:

• POLE Ultramutated: Features mutations in the DNA polymerase epsilon gene; carries an excellent prognosis and highly responds to therapy de-escalation.
• MSI-H / dMMR (Microsatellite Instability-High): Driven by DNA mismatch repair deficiency; highly responsive to immunotherapy.
• Copy-Number Low: Typically low-grade, endometrioid, and hormone-receptor positive.
• Copy-Number High (p53 Abnormal): Predominantly high-grade serous/non-endometrioid variants with TP53 mutations; carries a very poor prognosis.

Pathogenesis

The underlying development of endometrial cancer splits across two distinct biological mechanisms.

[Unopposed Estrogen] ➔ [Endometrial Hyperplasia] ➔ [PTEN / PIK3CA Mutations] ➔ Type I (Endometrioid) [Aged / Atrophic Tissue] ➔ [p53 Gene Dysregulation] ➔ [Chromosomal Instability] ➔ Type II (Serous / Clear Cell)

Hormonal Pathway (Type I)

• Driven by unopposed estrogen (high estrogen levels without balancing progesterone).
• Estrogen stimulates continuous endometrial cell proliferation.
• Triggers key genetic mutations, most notably the loss of the PTEN tumor suppressor gene, alongside KRAS and PIK3CA mutations.

Non-Hormonal Pathway (Type II)

• Completely independent of estrogen stimulation.
• Typically initiated by a TP53 tumor suppressor mutation, leading to high chromosomal instability and rapid cellular atypia.
• Lynch syndrome (an inherited mismatch repair gene mutation) serves as a primary genetic driver for hereditary cases.

Laboratory and Clinical Diagnosis

Because there is no standard screening test for asymptomatic individuals, evaluation relies on diagnostic procedures when symptoms emerge.

• Transvaginal Ultrasound (TVUS): Initial imaging choice to measure endometrial thickness; a stripe greater than 4 mm in postmenopausal women warrants action.
• Endometrial Biopsy: The gold standard for definitive diagnosis, performed in an outpatient clinic to obtain tissue.
• Dilatation & Curettage (D&C): Utilized if the outpatient biopsy yields insufficient tissue or remains inconclusive.
• Immunohistochemistry (IHC): Laboratory staining for mismatch repair proteins (MLH1, MSH2, MSH6, PMS2) and p53 expression to clarify molecular grading.
• Serum CA-125: A lab blood test monitored primarily to assess for extrauterine spread or monitor recurrence.

Treatment

Management is highly individualized based on the disease stage (FIGO staging) and histological traits.

Surgical Management (Cornerstone)

• Total Hysterectomy + Bilateral Salpingo-Oophorectomy (TH/BSO): Removal of the uterus, cervix, fallopian tubes, and ovaries.
• Lymphadenectomy: Sentinel lymph node biopsy or full pelvic/para-aortic lymph node dissection to evaluate for metastasis.

Adjuvant and Systemic Therapies

• Radiation Therapy: Pelvic external beam radiation or vaginal brachytherapy is utilized for localized, high-risk disease.
• Chemotherapy: Systemic platinum-based regimens (e.g., Carboplatin and Paclitaxel) target advanced, metastatic, or aggressive Type II histologies.
• Hormone Therapy: Progestins (e.g., Medroxyprogesterone acetate) are utilized for fertility-sparing preservation in early stages or palliation.
• Immunotherapy: Targeted checkpoint inhibitors (like Pembrolizumab or Dostarlimab) are deployed for advanced or recurrent mismatch repair-deficient (dMMR) tumors.

Prevention

Primary preventive strategies minimize environmental risk factors and manage hormonal balances.

• Weight Management: Maintaining a healthy BMI is crucial because adipose tissue converts androgens into active estrogen.
• Combined Oral Contraceptives: Birth control containing both estrogen and progesterone significantly slashes risk by preventing endometrial proliferation.
• Opposed Hormone Therapy: Always pair estrogen replacement therapy with a progestin if the patient still has an intact uterus.
• Metabolic Management: Controlling blood sugar and managing Type 2 Diabetes.
• Proactive Screening: Annual endometrial biopsies starting at age 35 for individuals confirmed to have Lynch syndrome.

Keynotes

• Primary Risk Factor: Obesity remains the most significant and modifiable risk factor for the disease.
• Cardinal Symptom: Any postmenopausal bleeding must be considered endometrial cancer until pathologically proven otherwise.
• Prognosis: Stage I endometrioid cancer boasts an excellent 5-year survival rate exceeding 90%.
• Paradigm Shift: Modern oncology has shifted away from purely observing tissue structures (histology) toward targeting the tumor’s precise genetic profile (molecular subtyping)

Further Readings

1. https://www.ncbi.nlm.nih.gov/books/NBK525981/
2. https://www.mdpi.com/2077-0383/14/4/1385
3. https://www.mayoclinic.org/diseases-conditions/endometrial-cancer/symptoms-causes/syc-20352461
4. https://www.msdmanuals.com/professional/oncology/gynecologic-tumors/endometrial-cancer
5. https://www.cancer.org/cancer/types/endometrial-cancer/treating.html
6. https://www.sciencedirect.com/science/article/pii/S1028455922003047
7. https://www.mdpi.com/2072-6694/16/5/1028
8. https://pmc.ncbi.nlm.nih.gov/articles/PMC11856752/
9. https://www.ummhealth.org/health-library/endometrial-cancer-introduction
10. https://www.researchgate.net/publication/375726586_Pathogenesis_and_Treatments_of_Endometrial_Carcinoma
11. https://www.annalsofoncology.org/article/S0923-7534(22)01207-8/fulltext
12. https://ijcap.in/archive/volume/8/issue/2/article/3368
13. https://www.aafp.org/afp/2016/0315/p468
14. https://pmc.ncbi.nlm.nih.gov/articles/PMC2962676/
15. https://pmc.ncbi.nlm.nih.gov/articles/PMC9035046/
16. https://www.sciencedirect.com/science/article/pii/S1751721424001714
17. https://journals.sagepub.com/doi/10.1177/14230380251410478