Prophylactic Para-Aortic Extended Field Irradiation with Concurrent Chemotherapy for FIGO Stage IIIC1 Cervical Cancer Using Intensity Modulated Radiotherapy Technique: Acute Toxicity and Dosimetric Assessment

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To evaluate the efficacy of P - PART with concurrent chemotherapy in LACC with the use of intensity modulated radiotherapy technique (IMRT). Our Primary endpoint was to assess acute toxicities and secondary endpoint was to assess loco-regional control (LRC), disease free-survival (DFS), para-aortic recurrence free survival (PA-RFS). A total of 30 patients of squamous cell carcinoma of cervix with stage IIIC1 (FIGO-2018) were recruited in this prospective, single arm interventional phase II study between January 2021 to September 2022. 18FDG-PET CT was performed and those with positive PALN were excluded. IMRT was used to deliver a dose of 50 Gy in 25 fractions to whole pelvis and PALN chain below renal hilum till aortic bifurcation received 45 Gy in 25 fractions. Concurrent cisplatin was administered weekly at 40 mg/m2 during radiation. On completion of external beam radiotherapy, high dose rate intracavitary brachytherapy was given at 7 Gy per fraction in 3 fractions prescribed to HR-CTV. Acute toxicities were assessed using CTCAE version 5.0. Median age was 50 years (37-66 years). All patients had completed treatment as per protocol. All patients had positive pelvic nodes with the maximum nodal short axis dimension of 14 mm (10-18 mm). All patients had positive internal iliac group of LNs, only 2(6.6%) patients had positive common iliac group of Ln. Median number of concurrent cisplatin cycles given were 5 (3-5 cycle). Median overall treatment time was 56 days (52-63 days) and median follow up was 15 months (3-22 month). Median cumulative dose to HR-CTV was 84.3Gy (Range:79.2-86.9Gy). Cumulative median EQD2 to 2cc of bladder and rectum were 69.11Gy (Range:59.17 - 80.07 Gy) and 64.6 Gy (Range: 60.1-66.3Gy) respectively. 7(23.3%) patients having grade 3 diarrhea and 2(6.67%) patients had grade 3 anemia while no significant genitourinary or other toxicities were noted. Patient characteristics, dosimetric data are described in Table-1. All patients underwent clinical and radiological assessment at the time of last follow up with one (3.33%) patient experiencing local failure at 9 months of follow up, hence crude LRC rate is 96.6%, DFS is 13.5 months (5-22 months) and PA-RFS is 16 months (8-23 months) till last date of follow up. Prophylactic EFRT with concurrent chemotherapy using IMRT technique yielded excellent short term clinical outcomes with acceptable toxicity profiles. Longer follow up will elucidate late toxicity and long-term clinical outcomes.