What radiotherapy regimen (dose, treatment fields, and brachytherapy schedule) was used in the RTOG 79‑20 protocol for women with locally advanced cervical cancer (FIGO IIB, bulky IB2‑IIA ≥5 cm, or positive pelvic nodes)?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: February 6, 2026 • View editorial policy

Personalize

Help us tailor your experience

Which best describes you? Your choice helps us use language that's most understandable for you.

RTOG 79-20 Protocol for Locally Advanced Cervical Cancer

The RTOG 79-20 protocol delivered pelvic plus para-aortic extended-field irradiation at 44-45 Gy in 4.5-6.5 weeks using daily fractions of 1.6-1.8 Gy for 5 days per week, followed by intracavitary brachytherapy delivering 4000-5000 mg/h radium equivalent (or 30-40 Gy) to point A. 1

External Beam Radiotherapy Specifications

Dose and Fractionation

  • The extended-field arm delivered 44-45 Gy to both the pelvis and para-aortic region over 4.5-6.5 weeks 1
  • Daily fraction size was 1.6-1.8 Gy, administered 5 days per week 1
  • The standard pelvic-only arm (control) delivered 40-50 Gy midplane pelvic dose using the same fractionation schedule 1

Treatment Fields

  • Pelvic plus para-aortic irradiation extended the superior border to include para-aortic lymph nodes up to the renal vessels 1
  • The upper limit of standard pelvic fields is at the L4-L5 junction, which can be lowered to L5-S1 for low-volume stage IB-IIA disease without nodal involvement 2
  • Four-field technique is recommended over two-field arrangements 2
  • Lateral field borders must always cover the nodal zones 2
  • The inferior margin requires a minimum 4 cm safety margin below the lowest tumor level 2

Brachytherapy Component

Dose Prescription

  • Total dose of 4000-5000 mg/h radium equivalent or 30-40 Gy to point A was delivered via intracavitary brachytherapy 1
  • This brachytherapy dose was combined with external beam to achieve adequate central tumor control 1
  • Low-dose-rate (LDR) brachytherapy was the standard technique during this era 2

Timing and Integration

  • Brachytherapy was administered after completion of external beam radiotherapy 1
  • The sequencing of external radiotherapy before brachytherapy does not affect results compared to alternating approaches 2
  • Initial external radiotherapy at minimum 40 Gy allows tumor shrinkage for optimal intracavitary placement 2

Clinical Outcomes and Implications

Survival Benefits

  • 10-year overall survival was 55% for pelvic plus para-aortic irradiation versus 44% for pelvic-only radiation (P=0.02) 1
  • Disease-free survival was similar between arms (42% vs 40%), but the extended-field arm showed lower distant failure rates in complete responders (P=0.053) 1
  • Better salvage rates for local failures occurred in the extended-field arm (25% vs 8%) 1

Toxicity Profile

  • Cumulative incidence of grade 4-5 toxicities at 10 years was 8% in the extended-field arm versus 4% in pelvic-only arm (P=0.06) 1
  • Death rate from radiotherapy complications was 2% (4/170 patients) in the extended-field arm versus 1% (1/167) in pelvic-only arm 1
  • Prior abdominal surgery significantly increased complications: 11% grade 4-5 toxicity with para-aortic irradiation after surgery versus 2% in pelvic-only arm 1
  • The risk of bowel complications is markedly elevated with para-aortic fields 2

Important Caveats

Patient Selection

  • RTOG 79-20 enrolled patients with FIGO stage IIB, bulky IB (≥4 cm), or bulky IIA (≥4 cm) cervical carcinomas 1
  • This protocol predates the concurrent chemoradiotherapy era, which is now standard of care 2
  • Modern treatment for these stages uses concurrent cisplatin-based chemotherapy with radiotherapy, which has demonstrated superior outcomes 2

Contemporary Context

  • Prophylactic para-aortic irradiation remains controversial, with benefit not clearly established and significantly increased bowel toxicity 2
  • When para-aortic irradiation is used prophylactically, 45 Gy is the standard dose 2
  • For proven para-aortic metastases (without distant disease), para-aortic radiotherapy is standard, though optimal dose remains undetermined 2

Technical Standards

  • Photon energy ≥10 MV is standard for external beam 2
  • CT-based treatment planning with conformal blocking is now mandatory 2, 3
  • Total treatment duration should not exceed 8 weeks, as each additional day decreases pelvic control by 0.5-1% 2, 3

References

2
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

3
Guideline

Image‑Guided Brachytherapy for Cervical Cancer – Evidence‑Based Guidelines

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

Related Questions

What is the survival rate for cervical cancer stage 3c?
What are the key randomized trials evaluating prophylactic para‑aortic irradiation in cervical cancer, and what were their findings regarding efficacy and toxicity?
Does stage IIB cervical cancer treatment with concurrent chemoradiation require initial inpatient admission?
What were the patient eligibility criteria, radiation schedules, and outcomes (local‑regional control, overall survival, toxicity) of the RTOG 79‑02 Phase III trial comparing accelerated fractionation to standard fractionation in stage III‑IV head‑and‑neck squamous cell carcinoma?
For an adult patient with multiple brain metastases, a controlled primary tumor, no extracranial disease, and Karnofsky performance status ≥70, what whole‑brain radiotherapy schedule is recommended based on RTOG 79‑20?
Which topical corticosteroid is appropriate for treating a rash on the breast skin?
In an older man requiring primary prevention, which statin has the lowest overall risk of adverse effects?
In a 67‑year‑old patient with type 2 diabetes, hypertension and an HbA1c of 7.4% who is on metformin, should empagliflozin be added to the regimen or replace metformin?
What dietary management is recommended for a patient with Food Protein‑Induced Enterocolitis Syndrome (FPIES)?

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.

Ask Question