Cervical cancer - Diagnosis and Staging

Diagnosis of Cervical Cancer Biopsy and Colposcopy To diagnose cervical cancer or its precursors, physicians must perform a biopsy—taking a tissue sample from the cervix for pathological examination. The most common way to obtain this sample is during a colposcopy, a procedure that provides a magnified view of the cervical surface. During colposcopy, the clinician applies dilute acetic acid to the cervix. This solution causes abnormal, dysplastic cells to appear white due to their increased nuclear density. Normal tissue remains unchanged. To enhance contrast further, Lugol's iodine is sometimes applied, which stains normal cervical tissue brown; abnormal areas do not stain and appear as yellow or white. This visual difference guides the clinician to areas most likely to contain significant disease. Two procedures commonly remove larger tissue samples for examination: Loop electrosurgical excision procedure (LEEP): Uses a heated wire loop to remove abnormal tissue Cervical conization: A cone-shaped piece of cervical tissue is removed surgically Both procedures remove a portion of the cervical lining for detailed pathological analysis. A key advantage of these procedures is that they are both diagnostic and therapeutic—they both identify the problem and may completely remove precancerous lesions. Precancerous Lesions: The CIN Classification System The most common precancerous finding in the cervix is cervical intraepithelial neoplasia (CIN), which refers to abnormal cells on the surface (epithelium) of the cervix. These lesions are caused by persistent infection with high-risk human papillomavirus (HPV). CIN is classified into three grades based on how abnormal the cells appear under the microscope: CIN 1 (mild dysplasia): Abnormal cells occupy the lower third of the epithelium; cells still retain some normal characteristics CIN 2 (moderate dysplasia): Abnormal cells extend into the middle third of the epithelium CIN 3 (severe dysplasia or carcinoma in situ): Abnormal cells occupy more than two-thirds of the epithelium; these cells are morphologically indistinguishable from cancer cells but have not invaded through the basement membrane Clinical Note: CIN 2 and CIN 3 are sometimes grouped together as CIN 2/3 in research and clinical practice because they carry similar risks for progression to invasive cancer and are managed similarly. Connecting CIN to Pap Test Results A key point that often confuses students is the relationship between Pap test results and CIN grades. The Pap test (cervical cytology) and biopsy (tissue histology) use different classification systems: A low-grade squamous intraepithelial lesion (LSIL) on a Pap test generally corresponds to CIN 1 on biopsy A high-grade squamous intraepithelial lesion (HSIL) on a Pap test generally corresponds to CIN 2 or CIN 3 on biopsy The distinction matters because these categories guide management decisions. LSIL (CIN 1) often regresses spontaneously and may be managed conservatively with close follow-up, while HSIL (CIN 2/3) typically requires excisional treatment to prevent progression to invasive cancer. Cancer Subtypes When CIN 3 progresses without treatment, it develops into invasive cervical cancer. The vast majority of cervical cancers arise from the squamous cells that line the cervix: Squamous cell carcinoma: Approximately 75% of cervical cancers Adenocarcinoma: Approximately 20–25% of cervical cancers (arising from glandular cells) This distribution is important because the two subtypes may have slightly different clinical behavior and treatment considerations, though both are strongly associated with HPV infection. Staging System Once cervical cancer is diagnosed, staging determines the extent of disease and guides treatment. The 2018 International Federation of Gynecology and Obstetrics (FIGO) staging system incorporates clinical examination findings, imaging studies (such as MRI or CT), and pathological information to assign each cancer to one of nine stages. The stages range from: Stage 1A: Microscopic disease confined to the cervix (not visible to the naked eye) Stage 1B: Clinically visible tumors confined to the cervix Stage 2: Tumor extends beyond the cervix but not to the pelvic sidewall or lower vagina Stage 3: Tumor extends to the pelvic sidewall or lower vagina, or involves pelvic lymph nodes Stage 4A: Tumor invades the bladder or rectal mucosa Stage 4B: Distant metastatic disease Subcategories within each stage (for example, 1A1, 1A2, 1B1, 1B2, 1B3) provide finer detail about tumor size and anatomical extent. These subcategories are clinically important because small differences in tumor size—particularly in stage 1 disease—can significantly affect treatment decisions and prognosis.