ESTRO 2024 - Abstract Book

S186

Brachytherapy - GI, paediatric, miscellaneous

ESTRO 2024

Material/Methods:

Between 2019 till 2023, 23 patients (18 liver metastases and 5 hepatocellular carcinoma) with 29 larger than 5cm liver lesion (no upper limit) who underwent CT-guided HDR-IBT using Iridium-192 source were prospectively followed up. Four patients were excluded from local tumor control and survival analyses as they died prior to the first radiological imaging assessment. All patients were either not suitable for surgery, refused liver resection or local liver directed treatment was deemed the best option in the multidisciplinary clinic. Percutaneous applicators were placed under CT-guidance and subsequently GTV was contoured on the axial slices. PTV = GTV and dose was prescribed to GTV/PTC margin. Prophylactic anti-emetics were prescribed to all patients. Radiological imaging (CT Scan, MRI or PET-CT) was performed at 3 monthly intervals after HDR-IBT. Primary endpoints are local control rate (tumour shrinkage or absence of progression in imaging), progression free survival [from first treatment date to local or distant progression (whichever occurred first) or last follow up date], overall survival (OS) and toxicity related to HDR-IBT. Major and minor complications were defined according to Society of Interventional Radiology reporting standards. We included 14 male and 5 female patients with a median age of 61 years (range 36–73 years). In 14 patients with liver metastasis, colorectal adenocarcinoma was the most common primary tumour type (50%), followed by pancreatic (14.3%), head and neck (14.3%), extrahepatic cholangiocarcinoma (14.3%) and breast (7.1%). Three patients had more than one HDR-IBT procedure for multiple liver lesions. Seven of treated liver lesions were centrally located. The median number of implanted catheters was 4 (range 2–7). Three patients had prior treatment to liver with surgery, RFA and/or TACE. The mean tumour diameter and volume is 8.1 cm (range, 5.0– 15.6 cm) and 190.8 cc (range 4.66 to 833.5 cc) respectively. The peripheral prescribed dose range from 15Gy to 25Gy in single fraction. The mean of (range) D99%, D95% and D90% is 16.7Gy (6.36 –23.64Gy), 20.56y (8.28 – 28.75Gy) and 23.41Gy (9.69 – 34.29Gy) respectively. Seven patients (37%) had disease progression during follow-up (local – treated lesion, regional in liver and distant). Out of 25 lesions treated, 1 lesion had PD (progressive disease) at 3.7 months follow up. With median follow up of 153 (range, 21-863) days, the local control rate, progression free survival and overall survival at 12 months was 94.4%, 46.9% and 28.2% respectively. One patient who had 5 sessions of HDR-IBT over 5 months for multiple liver lesions died of radiation induced liver disease (RILD). Most common acute toxicity is fever (62%), nausea and vomiting (76%) and pain (86%) which was well controlled with medications. No significant subcapsular bleeding seen during and after procedure. No patient needed blood transfusion. In one lesion that had PD, the D99%, D95% and D90% was 23.64Gy, 27.27Gy and 30.02Gy respectively. This patient had systemic chemotherapy for metastatic colorectal cancer prior to the liver HDR-IBT and it was a marginal recurrence. Results:

Conclusion:

We conclude that image-guided interstitial brachytherapy is feasible and effective in patients with primary and secondary liver malignancies up to approximately 10 cm. We did not identify the upper limit of the tumour size. Single fraction, CT-guided HDR brachytherapy generated results similar to RFA or TACE even in lesions either too large or inaccessible to these techniques.

Keywords: liver cancer, brachytherapy, CT-guided

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