FIGO 2018 Cervical Cancer Staging: A Paradigm Shift in Clinical Practice

By Dr. Jeff K. Mathe

Consultant Obstetrician & Gynecologist | Medical Educator | OBGYN Academy 360

Introduction

Cervical cancer remains a significant global health challenge, representing the fourth most common cancer in women worldwide. With approximately 600,000 new cases and over 340,000 deaths annually, the majority occurring in low- and middle-income countries, accurate staging is essential for treatment planning and prognostic assessment. The International Federation of Gynecology and Obstetrics (FIGO) revised its cervical cancer staging system in 2018, introducing fundamental changes that have reshaped clinical practice and improved prognostic stratification.

This article reviews the FIGO 2018 staging system, highlights key modifications from the 2009 system, and discusses the clinical implications of these changes for oncology professionals.

Historical Context: The Evolution of FIGO Staging

FIGO first established cervical cancer staging in 1928, completing its initial system in 1958. Prior to 2018, FIGO staging relied exclusively on clinical examination with only limited investigations permitted to modify stage allocation. This approach was designed to maintain global uniformity, particularly in resource-limited settings where advanced imaging and surgical techniques were unavailable.

However, this clinical-only approach had significant limitations. Studies demonstrated discordance between clinical and surgical staging in up to 25% of early-stage cases and 40% of advanced-stage cases. The inability to accurately assess tumor size, parametrial involvement, and lymph node status resulted in systematic understaging of stages IB through III and overstaging of stage IIIB disease.

The FIGO 2018 Revision: Major Changes

1. Integration of Imaging and Pathological Findings

The most transformative change in FIGO 2018 was the formal incorporation of imaging modalities and pathological findings for stage allocation. This represents a fundamental departure from the purely clinical approach of previous systems.

Key principle: When available, imaging and pathology can supplement clinical findings for tumor size and extent assessment across all stages. Pathological findings supersede imaging and clinical findings when discrepancies exist.

Recommended modalities:

  • High-resource settings: Pelvic MRI for tumor size and local disease assessment; FDG-PET/CT for lymph node evaluation and distant metastases

  • Resource-limited settings: Pelvic ultrasound and chest radiography

This flexibility allows the staging system to be implemented globally while taking advantage of technological advances where available.

2. Revised Stage IA Criteria

Stage IA disease is now defined solely by depth of invasion (≤5 mm), regardless of horizontal spread. The lateral extent criterion from the 2009 system has been removed, as depth of invasion is a superior predictor of lymph node metastasis and recurrence compared to horizontal spread.

FIGO 2018 Stage IA:

  • IA1: Measured stromal invasion <3 mm

  • IA2: Measured stromal invasion ≥3 mm and <5 mm

This simplification aligns with contemporary understanding of prognostic factors and facilitates more consistent staging across institutions.

3. Refined Stage IB Subdivisions

One of the most clinically significant modifications involves the subdivision of stage IB disease into three categories based on tumor size, providing more granular prognostic stratification:

FIGO 2018 Stage IB:

  • IB1: Clinically visible lesion ≤2 cm in greatest dimension

  • IB2: Clinically visible lesion >2 cm and <4 cm

  • IB3: Clinically visible lesion ≥4 cm

Comparison with FIGO 2009: The 2009 system used only a 4 cm cutoff (IB1 <4 cm; IB2 ≥4 cm). The new three-tier system better discriminates survival outcomes, with validation studies demonstrating distinct five-year survival rates: 97% for IB1, 92.1% for IB2, and 83.1% for IB3.

Multivariable analysis has confirmed that stage IB2 disease carries nearly twice the risk of cervical cancer mortality compared to IB1, while IB3 disease shows a four-fold increased risk compared to IB1 and approximately two-fold higher risk than IB2.

4. Introduction of Stage IIIC: Lymph Node Involvement

The incorporation of lymph node status represents perhaps the most revolutionary change in the FIGO 2018 system. For the first time, lymph node metastasis is explicitly included in staging, acknowledging its profound prognostic significance.

FIGO 2018 Stage IIIC:

  • IIIC1: Pelvic lymph node metastasis only (regardless of primary tumor characteristics)

  • IIIC2: Para-aortic lymph node metastasis (with or without pelvic nodes)

Critical staging principle: Any tumor with lymph node metastasis is upstaged to stage IIIC, regardless of primary tumor size or local extent. This reflects the known impact of nodal disease on survival, as five-year survival rates decrease from 80-90% in node-negative patients to 50-65% in those with lymph node metastasis.

The notation "r" (radiological) or "p" (pathological) may be added to indicate the method used to identify nodal involvement.

5. Stages II and IV: Minimal Changes

Stage II (disease extending beyond the cervix but not to pelvic wall or lower third of vagina) remains unchanged from FIGO 2009:

  • IIA: No parametrial involvement (IIA1: <4 cm; IIA2: ≥4 cm)

  • IIB: With parametrial involvement

Stage III now includes three substages:

  • IIIA: Involvement of lower third of vagina

  • IIIB: Extension to pelvic wall and/or hydronephrosis/non-functioning kidney

  • IIIC: Lymph node involvement (as described above)

Stage IV criteria remain similar but now formally allow imaging to identify distant metastases:

  • IVA: Spread to adjacent organs (bladder or rectal mucosa)

  • IVB: Distant metastasis

Clinical Impact and Stage Migration

Extent of Stage Migration

Implementation of FIGO 2018 has resulted in substantial stage migration. Multiple large-scale validation studies have documented:

  • Overall stage migration: 41-54% of patients are restaged when the 2018 criteria are applied retrospectively

  • Upstaging to IIIC: Approximately 20-28% of patients are upstaged to stage IIIC due to detection of lymph node metastasis

  • Stage I redistribution: Significant reallocation within stage I substages due to refined size criteria, with approximately 76% of stage I patients experiencing stage shifts

  • Detection of occult disease: Imaging identifies occult lymph node metastasis in approximately 41% and distant metastasis in an additional 12% of cases

Importantly, in these validation cohorts, virtually no patients were downstaged when comprehensive imaging and pathological assessment were applied.

Prognostic Discrimination

The FIGO 2018 system demonstrates improved survival discrimination, particularly for early and advanced stages:

Five-year progression-free survival by stage (2009 vs. 2018):

  • Stage I: 80% vs. 87% (p=0.02)

  • Stage II: 59% vs. 71% (p=0.002)

  • Stage III: 35% vs. 55% (p<0.001)

  • Stage IV: 20% vs. 16% (p=0.41)

These improvements reflect more accurate allocation of patients to prognostically homogeneous groups.

Heterogeneity in Stage IIIC

While stage IIIC acknowledges the importance of lymph node metastasis, outcomes within this stage remain heterogeneous. Survival is significantly influenced by:

  1. Primary tumor factors: Five-year survival rates for stage IIIC1 vary dramatically by T-stage:

    • T1: 74.8%

    • T2: 58.7%

    • T3: 39.3%

    • Absolute difference: 35.3% (p<0.001)

  2. Extent of nodal disease: IIIC2 (para-aortic nodes) demonstrates significantly worse prognosis compared to IIIC1 (pelvic nodes only), with hazard ratio of 2.13.

  3. Comparison with other stage III disease: Interestingly, stage IIIC1 shows improved survival compared to stage IIIB (adjusted HR 0.79, 95% CI 0.74-0.85), suggesting that nodal disease alone may have better outcomes than extensive local disease with pelvic wall involvement or hydronephrosis.

This heterogeneity suggests that future refinements may be needed to further stratify stage IIIC patients based on local tumor extent and nodal disease burden.

Implications for Clinical Practice

Treatment Planning

The FIGO 2018 system provides more precise information for treatment decision-making:

  1. Early-stage disease: The three-tier IB system helps identify patients who may benefit from different surgical approaches or adjuvant therapy strategies

  2. Lymph node assessment: The emphasis on nodal status highlights the importance of comprehensive lymph node evaluation through imaging or sentinel lymph node mapping

  3. Resource stratification: The flexibility to use available technology (from ultrasound to PET/CT) allows implementation across diverse healthcare settings

Fertility-Sparing Surgery

The refined stage IA criteria and improved tumor size assessment in stage IB1 facilitate more accurate patient selection for fertility-sparing procedures such as trachelectomy.

Radiation Therapy Planning

For locally advanced disease, the incorporation of imaging findings allows more accurate delineation of disease extent, optimizing radiation field planning and dose distribution.

Clinical Trial Design

The improved prognostic stratification provided by FIGO 2018 enables more homogeneous patient populations in clinical trials, potentially enhancing the ability to detect treatment effects.

Remaining Challenges and Future Directions

Despite its improvements, several challenges remain:

  1. Stage IIIC heterogeneity: The broad range of outcomes within stage IIIC suggests need for further substratification based on tumor burden and extent of nodal disease

  2. Imaging modality standardization: Variability in available imaging technology may lead to staging inconsistencies between institutions

  3. Isolated tumor cells: The clinical significance of isolated tumor cells in lymph nodes remains unclear

  4. Definition ambiguities: Some areas require further clarification, including precise measurement techniques and parametrial involvement criteria

Conclusion

The FIGO 2018 cervical cancer staging system represents a significant advancement in oncology practice, incorporating modern imaging and pathological assessment while maintaining applicability across diverse resource settings. The integration of lymph node status, refined tumor size criteria, and simplified stage IA definitions provide improved prognostic stratification and more accurate guidance for treatment planning.

For clinicians, the key takeaways include:

  • Imaging and pathology should be utilized when available to optimize staging accuracy

  • The three-tier stage IB system provides important prognostic information

  • Lymph node assessment is now a critical component of staging

  • Stage IIIC patients require careful evaluation of both local tumor factors and extent of nodal disease

As we accumulate more experience with this revised system, further refinements will likely emerge, particularly regarding substratification of stage IIIC disease. Nonetheless, FIGO 2018 represents a major step forward in our ability to accurately stage cervical cancer and optimize patient outcomes globally.

Key References

  1. Bhatla N, Berek JS, Cuello Fredes M, et al. Revised FIGO staging for carcinoma of the cervix uteri. Int J Gynecol Obstet. 2019;145(1):129-135. doi:10.1002/ijgo.12749 [Original FIGO 2018 staging publication with corrigendum]

  2. Bhatla N, Aoki D, Sharma DN, Sankaranarayanan R. Cancer of the cervix uteri. Int J Gynecol Obstet. 2018;143(Suppl 2):22-36. doi:10.1002/ijgo.12611 [FIGO Cancer Report 2018 chapter on cervical cancer management]

  3. Matsuo K, Machida H, Mandelbaum RS, Konishi I, Mikami M. Validation of the 2018 FIGO cervical cancer staging system. Gynecol Oncol. 2019;152(1):87-93. doi:10.1016/j.ygyno.2018.10.026 [Large SEER database validation study examining stage IB and III disease]

  4. Grigsby PW, Massad LS, Mutch DG, et al. FIGO 2018 staging criteria for cervical cancer: Impact on stage migration and survival. Gynecol Oncol. 2020;157(3):639-643. doi:10.1016/j.ygyno.2020.03.027 [Comprehensive analysis of stage migration in 1,282 patients with FDG-PET imaging]

  5. Lee SI, Atri M. 2018 FIGO Staging System for Uterine Cervical Cancer: Enter Cross-sectional Imaging. Radiology. 2019;292(1):15-24. doi:10.1148/radiol.2019190088 [Expert review on the role of imaging in the revised staging system]

  6. Salib MY, Russell JHB, Stewart VR, et al. 2018 FIGO Staging Classification for Cervical Cancer: Added Benefits of Imaging. Radiographics. 2020;40(6):1807-1822. doi:10.1148/rg.2020200013 [Comprehensive imaging review with clinical examples]

  7. Bhatla N, Singhal S, Dhamija E, et al. Implications of the revised cervical cancer FIGO staging system. Indian J Med Res. 2021;154(2):273-284. doi:10.4103/ijmr.IJMR_4225_20 [Analysis of implications for low- and middle-income countries]

  8. Wright JD, Matsuo K, Huang Y, et al. Prognostic Performance of the 2018 International Federation of Gynecology and Obstetrics Cervical Cancer Staging Guidelines. Obstet Gynecol. 2019;134(1):49-57. doi:10.1097/AOG.0000000000003311 [Validation using National Cancer Database with 45,872 patients]

  9. Ayhan A, Aslan K, Bulut AN, et al. Is the revised 2018 FIGO staging system for cervical cancer more prognostic than the 2009 FIGO staging system for women previously staged as IB disease? Eur J Obstet Gynecol Reprod Biol. 2019;240:209-214. doi:10.1016/j.ejogrb.2019.07.002 [Comparative analysis of 2009 vs 2018 staging for early disease]

  10. Balcacer P, Shergill A, Litkouhi B. Revised 2018 International Federation of Gynecology and Obstetrics (FIGO) cervical cancer staging: A review of gaps and questions that remain. Int J Gynecol Cancer. 2020;30(6):873-878. doi:10.1136/ijgc-2020-001257 [Critical analysis of remaining controversies and areas needing clarification]