Radiat Oncol J.  2021 Sep;39(3):219-230. 10.3857/roj.2020.00948.

Dose escalated simultaneous integrated boost of gross nodal disease in gynecologic cancers: a multi-institutional retrospective analysis and review of the literature

• Jensen GL
• Mezera MA
• Hasan S
• Hammonds KP
• Swanson GP
• El-Ghamry MN

• KMID: 2520458
• DOI: http://doi.org/10.3857/roj.2020.00948

Abstract

Purpose
Typical doses of 45–50.4 Gy used to treat regional nodes have demonstrated inadequate control of gross nodal disease (GND) in gynecologic cancer, and accelerated repopulation may limit the efficacy of a sequential boost. We reviewed outcomes of patients treated with a simultaneous integrated boost (SIB) at 2.25 Gy per fraction to positron emission tomography (PET) avid GND to evaluate toxicity and tumor control using this dose-escalated regimen.
Materials and Methods
A total of 83 patients with gynecologic cancer and PET avid inguinal, pelvic, or para-aortic lymphadenopathy were treated using intensity-modulated radiation therapy (IMRT) with SIB. Primary cancers were mostly cervical (51%) and endometrial (34%), and included patients who received concurrent chemotherapy (59%) and/or brachytherapy boost (78%).
Results
Median follow-up from radiation completion was 12.6 months (range, 2.7 to 92.9 months). Median dose to elective lymphatics was 50.4 Gy (range, 45 to 50.4 Gy) at 1.8 Gy/fraction. Median SIB dose and volume were 63 Gy (range, 56.3 to 63 Gy) and 72.8 mL (range, 6.8 to 1,134 mL) at 2–2.25 Gy/fraction. Nodal control was 97.6% in the SIB area while 90.4% in the low dose area (p = 0.013). SIB radiotherapy (RT) field failure-free, non-SIB RT field failure-free, and out of RT field failure-free survival at 4 years were 98%, 86%, and 51%, respectively. Acute and late grade ≥3 genitourinary toxicity rates were 0%. Acute and late grade ≥3 gastrointestinal toxicity rates were 7.2% and 12.0%, respectively.
Conclusion
Dose escalated SIB to PET avid adenopathy results in excellent local control with acceptable toxicity.

Keyword

Lymphadenopathy; Dose fractionation, Radiation; Radiation dosage