How is the staging of cervical cancer determined?

Staging of Cervical Cancer

Cervical cancer staging is determined using the International Federation of Gynecology and Obstetrics (FIGO) classification system, which since 2018 incorporates clinical examination, radiologic imaging (particularly MRI), and pathologic findings including lymph node status to guide treatment decisions that directly impact survival. 1

Core Staging Components

Clinical Foundation

• Clinical gynecological examination remains the fundamental basis for FIGO staging, as it allows worldwide standardization even in resource-limited settings 1
• The examination should assess tumor size, vaginal extension, parametrial involvement, and potential bladder or rectal extension 1
• Important caveat: Clinical staging alone has significant limitations, with concordance to pathological findings only 53.1% for stages IB-IIB, and accuracy drops dramatically in higher stages (only 20.5% concordance in stage IIB) 2

Essential Laboratory Workup

• Complete blood count including platelets 1
• Renal function tests (critical as hydronephrosis defines stage IIIB) 1
• Liver function tests 1
• Squamous cell carcinoma (SCC) antigen if squamous histology—useful for follow-up if initially elevated 1

Imaging Strategy (Critical for Treatment Planning)

MRI: The Preferred Modality

MRI is superior to CT for tumor extension assessment and should be the preferred imaging modality for pelvic and abdominal evaluation 1, 3

• MRI demonstrates 100% sensitivity and 85.7% specificity for parametrial infiltration 4
• MRI shows 100% sensitivity and 90% specificity for vaginal infiltration 4
• MRI is essential for measuring tumor size accurately (critical for distinguishing IB1 vs IB2, IIA1 vs IIA2) 1, 5
• MRI can detect disease high in the endocervix that may be missed on clinical examination 1

Key technical point: While MRI findings guide treatment decisions in clinical practice, the 2018 FIGO revision now formally incorporates imaging findings into official staging 1, 5

When Imaging is Required

• Mandatory for any clinically visible tumor or microscopic tumor with >5 mm invasion (stage IB or greater) 1
• Optional for stage IB1 or smaller tumors, though many centers still obtain imaging 1

Additional Imaging Modalities

• Chest imaging: Chest radiograph or thoracic CT for metastasis assessment 1
• PET/CT: Increasingly important with 2018 FIGO staging incorporating lymph node status; PET/CT shows high sensitivity (100%) and specificity (99%) for nodal disease 1, 5
• CT pelvis: Equal to MRI for nodal assessment but inferior for local tumor extension 1

Invasive Staging Procedures (Selective Use)

• Cystoscopy: Only if bladder extension is clinically suspected 1
• Proctoscopy: Only if rectal extension is clinically suspected 1
• Surgical lymph node staging (pelvic and para-aortic): Optional but provides most accurate nodal assessment 1

Critical Staging Distinctions That Alter Treatment

Early-Stage Disease (Surgery Candidates)

• Stage IA1: ≤3 mm stromal invasion, ≤7 mm horizontal spread 1
• Stage IA2: >3 mm but ≤5 mm stromal invasion, ≤7 mm horizontal spread 1
• Stage IB1: Clinically visible lesion ≤4 cm 1
• Stage IB2: Clinically visible lesion >4 cm 1
• Stage IIA1: Vaginal involvement (upper 2/3) without parametrial extension, ≤4 cm 1

Treatment implication: Tumors ≤4 cm without parametrial invasion (stages IA2-IIA1) are surgical candidates with radical hysterectomy and lymphadenectomy 1

Advanced Disease (Chemoradiation Candidates)

• Stage IB3: >4 cm (added in 2018 revision) 1
• Stage IIA2: Vaginal involvement >4 cm 1
• Stage IIB: Parametrial extension 1
• Stage III: Pelvic wall extension, lower 1/3 vagina, or hydronephrosis 1
• Stage IVA: Bladder or rectal mucosa invasion 1

Treatment implication: Tumors >4 cm or with parametrial/pelvic wall extension require primary chemoradiation 1

Special Considerations

Lymphovascular Space Invasion (LVSI)

• LVSI does not alter FIGO stage because pathologists lack consistent agreement on its presence 1
• However, some experts recommend treating stage IA1 with extensive LVSI using stage IB1 treatment protocols 1

2018 FIGO Update: Lymph Node Status

The 2018 revision now incorporates lymph node involvement into staging, designating positive pelvic nodes as stage IIIC1 and positive para-aortic nodes as stage IIIC2, regardless of local tumor extent 1, 5

This change reflects the critical prognostic importance of nodal status and emphasizes the role of cross-sectional imaging (particularly PET/CT) in modern staging 5

Common Pitfall

Clinical examination frequently overestimates disease stage (37.3% overestimation rate), particularly in assessing parametrial invasion 2. This is why the 2018 FIGO revision incorporated imaging—to improve accuracy and prevent overtreatment with chemoradiation when surgery would be curative 1, 5.