Gynecological Cancer

PV QA 4 - Poster Viewing Q&A 4

TU_14_3456 - Control of PET-positive lymph nodes treated with definitive chemoradiation in locally advanced cervical cancer

Tuesday, October 23
2:45 PM - 4:15 PM
Location: Innovation Hub, Exhibit Hall 3

Control of PET-positive lymph nodes treated with definitive chemoradiation in locally advanced cervical cancer
R. W. Gao1, C. R. Shideman2, D. C. Mathew1, K. E. Dusenbery1, M. A. Reynolds1, C. Rivard1, and J. Yuan1; 1University of Minnesota Medical School, Minneapolis, MN, 2Minneapolis Radiation Oncology, Minneapolis, MN

Purpose/Objective(s): Pelvic and/or para-aortic lymph node (LN) involvement at diagnosis is a significant prognostic factor for cervical cancer. The optimal treatment technique for nodal disease has not been well established. We retrospectively reviewed the treatment and outcomes of patients with PET-positive LN metastases treated with definitive chemoradiation at our institution.

Materials/Methods: Cervical cancer patients with PET-positive nodes treated with curative intent at our institution from 2006 to 2017 were identified. All patients received external beam radiotherapy with concurrent weekly cisplatin followed by brachytherapy. Patients with no follow-up imaging were excluded. Nodal treatment techniques (no boost [NB] vs. sequential boost [SEB] vs. simultaneously integrated boost [SIB]) were recorded. Total dose to each LN was converted to equivalent of 2-Gy (EQD2). Nodal control was assessed using follow-up PET/CT and/or CT imaging. Nodal failure was defined as persistence or increase in PET avidity or increase in size on CT. Nodal failure free rates were calculated using the maximum likelihood method.

Results: A total of 136 positive nodes from 43 patients were included in the analysis. Nodal distribution was as follows: 93 low pelvis (external iliac, internal iliac, obturator), 22 common iliac, 20 para-aortic, and 1 inguinal. The involved LN had a median pre-treatment size of 1.3 cm (range: 0.5-4.5 cm) and median standardized uptake value (SUV) of 7.8 (range: 2.3-19.2). A majority of the nodes were treated with intensity modulated radiation therapy with an SEB (45.6%) or SIB (45.6%) to a median cumulative EQD2 of 5448 cGy (range: 4425-6549 cGy). At a median follow up of 763 days, 9 of the 136 (6.6%) treated nodes in 6 of the 43 (14.0%) patients experienced failure: 6 low pelvic, 2 common iliac, and 1 para-aortic. The failed LN had a median size of 1.5 cm (range: 0.9-3.2 cm) and median SUV of 6.1 (range: 2.3-14.3). Median time from treatment initiation to nodal failure was 113 days (range: 85-447 days). The 1- and 2-year nodal failure free rates were 86.5% and 76.9% in the cohort of 43 patients, and 95.0% and 87.3% for all 136 metastatic LN. Crude control rates were 95.2% (59/62) in LN treated with SEB compared to 91.9% (57/62) in LN treated with SIB. There were no acute grade 3+ non-hematologic toxicities. Nine patients experienced late grade 3-5 toxicities, including fistula formation (n=4), small bowel obstruction (n=2), rectal bleeding (n=2), ureteral stricture (n=1), and vaginal stenosis (n=1).

Conclusion: Concurrent chemoradiotherapy using either a sequential or simultaneous integrated boost provides excellent local control of PET-positive LN in cervical cancer patients and is well tolerated.

Author Disclosure: R.W. Gao: None. C.R. Shideman: None. D.C. Mathew: None. K.E. Dusenbery: None. C. Rivard: None. J. Yuan: None.

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