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01Pathophysiology

Cervical cancer arises from the transformation zone of the cervix, where columnar epithelium of the endocervix meets the squamous epithelium of the ectocervix. This junction is the most metabolically active area of the cervix and is uniquely vulnerable to HPV infection because of its high rate of squamous metaplasia.

Persistent infection with high-risk HPV (primarily types 16 and 18) is the necessary precondition for nearly all cervical cancers. HPV gains access to the basal epithelial cells through microabrasions. Once integrated into the host genome, two viral oncoproteins drive malignant transformation. E6 binds and degrades p53 through the ubiquitin-proteasome pathway, eliminating the cell's ability to undergo apoptosis and DNA damage repair. E7 binds and inactivates the retinoblastoma protein (Rb), releasing E2F transcription factors and driving uncontrolled cell cycle progression past the G1/S checkpoint. The combined loss of both tumor suppressors results in genomic instability, accumulation of mutations, and progression from CIN I to CIN II to CIN III (carcinoma in situ) and eventually invasive carcinoma. This progression typically takes 10 to 20 years, which is why screening is so effective.

The reason patients present with postcoital bleeding is that the neoplastic tissue in the transformation zone is friable and highly vascularized. Mechanical contact during intercourse disrupts these fragile vessels. As the tumor grows, it may invade the parametria, compress the ureters (causing hydronephrosis and flank pain), invade the bladder or rectum, or obstruct lymphatic drainage (causing lower extremity edema). Foul-smelling discharge occurs from tumor necrosis and secondary bacterial infection of the necrotic tissue.

02Classification and Clinical Manifestation

Histological Classification

Cervical Intraepithelial Neoplasia (CIN) and Bethesda Classification

FIGO Staging (Clinical Staging)

A critical exam concept: cervical cancer is staged clinically, not surgically. This is because the disease is most prevalent in low-resource settings where surgical staging is not feasible. The staging relies on physical examination, colposcopy, biopsy, and basic imaging (chest X-ray, IVP, cystoscopy, proctoscopy). However, in practice, MRI is now the preferred imaging modality for assessing tumor size, parametrial invasion, and nodal involvement.

03Diagnostic Workup

Screening Approach

The entry point into cervical cancer diagnosis is almost always through screening, not symptoms. Current guidelines recommend:

For patients aged 21 to 29, Pap smear alone every 3 years is the standard. HPV testing is not recommended in this age group because transient HPV infections are extremely common and would generate unnecessary follow-up.

For patients aged 30 to 65, Pap smear + HPV co-testing every 5 years is preferred. Alternatively, Pap smear alone every 3 years or primary HPV testing alone every 5 years are acceptable. Screening can be discontinued after age 65 if prior results have been consistently normal.

Triage of Abnormal Results

When the Pap smear returns as ASC-US (atypical squamous cells of undetermined significance), the next step is reflex HPV testing. If HPV-positive, proceed to colposcopy. If HPV-negative, return to routine screening.

When cytology shows LSIL, proceed directly to colposcopy (HPV testing is not needed because LSIL has a high rate of HPV positivity).

When cytology shows HSIL or AGC (atypical glandular cells), proceed directly to colposcopy with endocervical curettage. HSIL warrants immediate evaluation because the risk of CIN II or worse is approximately 50-70%.

Diagnosis Confirmation

Colposcopy with directed biopsy is the gold standard for diagnosing cervical dysplasia and early invasive cancer. The colposcopist applies acetic acid (3-5%) to the cervix; dysplastic areas turn white (acetowhite changes) because of increased nuclear density. Lugol iodine (Schiller test) can also be applied: normal glycogen-rich squamous epithelium stains dark brown, while dysplastic areas remain unstained (Schiller-positive).

If the entire transformation zone cannot be visualized (unsatisfactory colposcopy), or if the ECC returns positive, a cone biopsy (excisional procedure) is required to rule out invasive disease.

04Management and Treatment

Precancerous Lesions (CIN II-III) The treatment of choice is LEEP, which uses a thin wire loop with electrical current to excise the transformation zone. It serves as both diagnostic (provides a specimen for histologic evaluation of margins) and therapeutic. The procedure is performed in an outpatient setting under local anesthesia. Cold knife conization is reserved for situations where a larger or deeper specimen is needed, such as suspected adenocarcinoma in situ (AIS) or when colposcopy is inadequate. After excision, patients are followed with co-testing at 12 and 24 months.

Early Invasive Cancer (Stage IA1 to IIA) For microinvasive disease (Stage IA1 without lymphovascular space invasion), cone biopsy with clear margins is sufficient and allows fertility preservation. If childbearing is complete, simple hysterectomy is an alternative.

For Stage IA2 through IB1, radical hysterectomy (removal of the uterus, parametria, upper vagina, and uterosacral ligaments) with bilateral pelvic lymph node dissection is the standard surgical approach. Ovaries can be preserved in premenopausal patients with squamous cell carcinoma because ovarian metastasis is rare.

For patients who desire fertility preservation with tumors ≤2 cm, radical trachelectomy (removal of the cervix with preservation of the uterine corpus) with lymphadenectomy is an option.

Locally Advanced Cancer (Stage IIB and Beyond) Once the tumor has invaded the parametrium (Stage IIB), surgery is no longer the primary treatment. The standard of care is concurrent chemoradiation: cisplatin 40 mg/m² IV administered weekly during external beam radiation therapy (EBRT), followed by intracavitary brachytherapy. The total treatment duration should not exceed 8 weeks, as prolonged treatment time is associated with worse outcomes. Cisplatin acts as a radiosensitizer, improving the efficacy of radiation.

Adjuvant Therapy After Surgery If pathology after radical hysterectomy reveals high-risk features (positive margins, parametrial invasion, or positive lymph nodes), the patient should receive adjuvant chemoradiation (Sedlis criteria for intermediate risk; Peters criteria for high risk). Intermediate-risk factors (large tumor size, deep stromal invasion, LVSI) may warrant adjuvant radiation alone.

05Differential Diagnosis and Distractors

06Traps and High-Yield Pearls

The most common way students lose points on cervical cancer questions is by confusing screening intervals and triage algorithms. Test-writers frequently present an ASC-US Pap result and ask for the next step. The answer is reflex HPV testing, not immediate colposcopy. Conversely, when the Pap shows HSIL, the next step is colposcopy, and you should not waste time with HPV testing because the pre-test probability of significant dysplasia is already high enough to warrant direct evaluation.

Another classic trap involves the management threshold at Stage IIB. Students often select radical hysterectomy for locally advanced disease, but once parametrial invasion is present, the correct answer shifts to concurrent chemoradiation. Remember: parametrial invasion = no surgery as primary treatment.

A frequently tested pearl is the distinction between HPV 16 and HPV 18. HPV 16 is the most common cause of cervical cancer overall and is strongly linked to squamous cell carcinoma. HPV 18 is more closely associated with adenocarcinoma. This matters because adenocarcinoma arises higher in the endocervical canal and may be missed by standard Pap smear, which is why HPV co-testing improves detection.

Students also confuse CIN I with LSIL as an indication for treatment. CIN I has a high rate of spontaneous regression, and the correct answer is surveillance, not LEEP. Treatment is reserved for CIN II and above. The exception is persistent CIN I lasting more than 2 years.

Regarding the HPV vaccine, it covers HPV types 6, 11 (responsible for genital warts), 16, and 18 (the 9-valent vaccine adds types 31, 33, 45, 52, and 58). Vaccination does not eliminate the need for screening because it does not cover all oncogenic HPV strains.

Finally, remember that cervical cancer is clinically staged, unlike endometrial and ovarian cancer, which are surgically staged. This distinction is a favorite question format: presenting a patient with cervical cancer and asking whether operative findings change the stage. They do not.