7.5 Gynecologic Oncology & Pelvic Mass Evaluation
Key Takeaways
- Cervical cancer screening in Canada relies on cytology or primary HPV DNA testing; persistent high-risk HPV types 16 and 18 cause >70% of cervical dysplasias and invasive carcinomas.
- Endometrial carcinoma is the most common gynecologic malignancy, presenting with postmenopausal bleeding; major risk factors involve prolonged unopposed estrogen (obesity, nulliparity, PCOS, tamoxifen, Lynch syndrome).
- Epithelial ovarian cancer (serous sub-type) predominates in postmenopausal women with CA-125 elevation and complex ultrasound features, triaged using the Risk of Malignancy Index (RMI >200 warrants gynecologic oncology referral).
- Malignant germ cell tumors (yolk sac tumor with elevated AFP, dysgerminoma with elevated LDH, choriocarcinoma with elevated β-hCG) typically affect adolescents and young women under 30 years.
- Lichen Sclerosus is a chronic autoimmune vulvar dermatosis carrying a 4–5% risk of transformation to vulvar squamous cell carcinoma, requiring high-potency topical corticosteroids (clobetasol) and surveillance.
Gynecologic Oncology & Pelvic Mass Evaluation
Gynecologic malignancies represent a significant cause of female cancer morbidity and mortality. Early recognition, accurate triage of adnexal masses, and adherence to SOGC and FIGO staging guidelines are key competencies evaluated on the MCCQE Part I.
Cervical Cancer Screening, HPV, & Dysplasia
Cervical cancer is almost universally caused by persistent infection with high-risk oncogenic strains of Human Papillomavirus (HPV), predominantly types 16 and 18 (responsible for >70% of invasive cervical cancers).
Oncogenic Mechanism
- E6 Oncoprotein: Binds and promotes ubiquitin-mediated degradation of the p53 tumor suppressor protein.
- E7 Oncoprotein: Binds and inactivates the Retinoblastoma (Rb) tumor suppressor protein, accelerating cell cycle progression from G1 to S phase.
Canadian Screening Guidelines (SOGC)
- Initiation: Cytology (Pap test) screening starts at age 21 or 25 (depending on provincial guidelines) for individuals who are or have been sexually active.
- Frequency: Cytology every 3 years until age 65.
- Transition to Primary HPV DNA Screening: Canadian guidelines recommend transitioning to primary HPV testing every 5 years for individuals aged 30–65.
- Bethesda System Cytology Triage:
- ASC-US (Atypical Squamous Cells of Undetermined Significance): Repeat Pap in 6 months OR perform reflex HPV DNA testing. If HPV positive → Colposcopy.
- LSIL (Low-grade Squamous Intraepithelial Lesion): Corresponds to CIN-1. Referral for colposcopy.
- HSIL (High-grade Squamous Intraepithelial Lesion): Corresponds to CIN-2 or CIN-3. Immediate colposcopy; managed with Loop Electrosurgical Excision Procedure (LEEP) or cervical cone biopsy.
- AGC (Atypical Glandular Cells): High risk of endometrial or cervical adenocarcinoma. Requires colposcopy, endocervical curettage (ECC), AND endometrial biopsy (Pipelle).
Endometrial Carcinoma
Endometrial carcinoma is the most common gynecologic cancer in North America.
Pathophysiology & Risk Factors
The primary driver for Type I endometrioid carcinoma is prolonged, unopposed estrogen exposure without sufficient progestin counter-regulation:
- Obesity: Increased peripheral aromatization of androstenedione to estrone in adipose tissue.
- Endogenous Estrogen: Nulliparity, early menarche (<12 yrs), late menopause (>55 yrs), polycystic ovary syndrome (PCOS, chronic anovulation).
- Exogenous Estrogen: Estrogen-only menopausal hormone therapy, Tamoxifen therapy (selective estrogen receptor modulator that acts as an agonist on the endometrium).
- Genetic Syndromes: Lynch Syndrome (Hereditary Non-Polyposis Colorectal Cancer - HNPCC), carrying up to a 60% lifetime risk of endometrial cancer.
- Protective Factors: Multiparity, combined oral contraceptive pills (progestin component stabilizes endometrium), physical activity.
Clinical Presentation & Staging
- Symptom: >90% of cases present with postmenopausal bleeding (PMB) or abnormal perimenopausal bleeding.
- Diagnosis: Endometrial tissue biopsy (Pipelle sampling) or Dilation & Curettage (D&C).
- FIGO Surgical Staging: Total Abdominal Hysterectomy + Bilateral Salpingo-Oophorectomy (TAH-BSO) + pelvic/para-aortic lymph node dissection.
Evaluation of Pelvic & Adnexal Masses
When evaluating an adnexal mass, the primary goal is distinguishing benign functional cysts from malignant neoplasms.
Transvaginal Ultrasound (TVUS) Diagnostic Characteristics
| Feature | Benign Ultrasonographic Features | Malignant Ultrasonographic Features |
|---|---|---|
| Structure | Simple cyst, unilocular, smooth thin wall (<3 mm) | Multilocular, thick septations (>2–3 mm), solid components |
| Echogenicity | Anechoic fluid | Complex, heterogeneous, internal papillary projections |
| Vascularity | Low color Doppler vascular flow | High-flow internal vascularity with low resistance |
| Associated Findings | Absence of peritoneal fluid | Ascites, peritoneal nodularity, bilateral masses |
Ovarian Tumor Markers by Age Group
- Postmenopausal Women (Epithelial Tumors - 90% of Ovarian Cancers):
- CA-125: Serum marker elevated in serous epithelial ovarian carcinoma. Note: CA-125 is non-specific in premenopausal women (elevated in endometriosis, fibroids, PID, pregnancy).
- HE4 (Human Epididymis Protein 4): Complementary marker for epithelial ovarian cancer.
- Adolescents & Young Women <30 Years (Germ Cell & Sex Cord Tumors):
- Dysgerminoma: Elevated LDH (Lactate Dehydrogenase).
- Yolk Sac Tumor (Endodermal Sinus Tumor): Elevated AFP (Alpha-Fetoprotein).
- Choriocarcinoma: Elevated β-hCG.
- Granulosa Cell Tumor (Sex cord-stromal): Secretes Estrogen and Inhibin B; presents with precocious puberty or postmenopausal bleeding.
- Sertoli-Leydig Cell Tumor: Secretes Testosterone; presents with rapid virilization (hirsutism, voice deepening, clitoromegaly).
Risk of Malignancy Index (RMI)
SOGC recommends using RMI to triage pelvic masses for gynecologic oncology referral:
- $U$ = Ultrasound score (0, 1, or 3 based on multilocularity, solid areas, ascites, metastases, bilateral lesions).
- $M$ = Menopausal status (1 = Premenopausal; 3 = Postmenopausal).
- $\text{CA-125}$ = Serum concentration in U/mL.
- RMI >200: Indicates high malignancy risk and mandates referral to a Gynecologic Oncologist.
Vulvar Carcinoma & Lichen Sclerosus
- Vulvar Squamous Cell Carcinoma: Accounts for 90% of vulvar cancers. Typically presents in postmenopausal women with chronic vulvar pruritus, pain, or a visible vulvar mass/ulcer.
- Mandatory Diagnostic Procedure: Vulvar Punch Biopsy (Keyes punch) under local anesthesia for any persistent or suspicious vulvar lesion.
- Lichen Sclerosus: Chronic autoimmune dermatosis characterized by porcelain-white crinkled plaques, loss of vulvar architecture (resorption of labia minora), and perianal "figure-of-eight" distribution. Carries a 4–5% risk of malignant transformation to SCC. Treatment: High-potency topical corticosteroids (Clobetasol propionate 0.05% ointment daily for 3 months, then maintenance).
SOGC Clinical Practice Pearls & Exam Traps
⚠️ EXAM TRAP: CA-125 is NOT a screening test for ovarian cancer in asymptomatic women! It is utilized for evaluating suspicious adnexal masses in postmenopausal women and for monitoring treatment response in known epithelial ovarian cancer.
🩺 CLINICAL SCENARIO: An 18-year-old female presents with acute right lower quadrant pain. Ultrasound reveals an 8 cm solid and cystic right adnexal mass. Serum lab results show: β-hCG negative, CA-125 18 U/mL, and Alpha-Fetoprotein (AFP) 4,200 IU/mL. What is the diagnosis?
- Diagnosis: Yolk Sac Tumor (Endodermal Sinus Tumor) of the ovary, a malignant germ cell tumor characteristic of young females that specifically produces elevated serum AFP.
A 62-year-old postmenopausal woman is evaluated for abdominal bloating and early satiety. Pelvic examination reveals a fixed, nodular right adnexal mass. Transvaginal ultrasound demonstrates a 7 cm multilocular right ovarian mass with solid papillary components and moderate ascites. Serum CA-125 is 340 U/mL. What is the most appropriate management according to SOGC guidelines?
A 19-year-old woman presents to the student health clinic with right lower quadrant discomfort. Pelvic ultrasound reveals a 6.5 cm complex right ovarian mass containing solid elements. Laboratory evaluation shows serum Alpha-Fetoprotein (AFP) is 3,800 IU/mL, while serum β-hCG and CA-125 are normal. Which ovarian neoplasm is most consistent with these findings?
A 67-year-old woman presents with a 6-month history of severe vulvar itching. On examination, there are diffuse porcelain-white, thin plaques extending across the labia majora and perineum in a figure-of-eight distribution, with resorption of the labia minora. A punch biopsy confirms Lichen Sclerosus. What is the first-line treatment regimen and major long-term risk associated with this condition?