PV QA 4 - Poster Viewing Q&A 4
Purpose/Objective(s): Regional nodal irradiation improves survival and reduces development of metastases in locally advanced gynecologic cancers. However, typical doses of 45-50 Gy have been shown to be inadequate to control gross nodal disease. Sequential boost may have low effect due to accelerated repopulation. At our institutions, we utilize a regimen of IMRT to 45-50.4 Gy at 1.8 Gy/fraction to elective nodal volumes (e.g. pelvic and para-aortic nodes) with SIB up to 56.25-63 Gy at 2.25 Gy/fraction to PET avid gross nodal disease. The purpose of this study is to evaluate toxicity and tumor control using this dose-escalated regimen.
Materials/Methods: Patients with gynecologic cancers presenting with PET avid para-aortic, pelvic, and/or inguinal lymph nodes were treated with IMRT-SIB between 2009 and 2017. Toxicity was evaluated throughout treatment and at routine follow up visits. Disease recurrence and response was identified by imaging and/or biopsy.
Results: A total of 52 patients were evaluated. The mean age was 54.2 years (± 11.7). Median follow up from completion of treatment was 11.2 months (0.9-90.4). The primary site of disease consisted of the cervix (50%), uterine (32.7%), and vulva (7.7%). Concurrent chemotherapy was given to 61.5% of patients. Brachytherapy was given to 82.7% of patients. The median SIB volume was 74.24 cc (range 6.75-858.42). Local control within the high dose integrated boost region was 97%. Radiologic complete and partial response was 65% and 21% respectively. A majority of the recurrences (63.6%) were distant with only 13.6% of patients having a recurrence in the elective dose field and 31.8% of patients having both a low dose and out of field recurrences. Median time to recurrence was 3.7 months (0-56.6). ≥Grade 3 acute toxicities were observed in 6% of patients. Late recto-vaginal fistula was observed in 13.5%, and was related to brachytherapy.
Conclusion: Dose escalated SIB results in excellent local control with acceptable toxicity. Almost all patients achieved radiographic partial or complete response with exceptionally low rate of recurrence within the dose-escalated boost volume.
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