Brachytherapy reirradiation with hyaluronate gel injection of paraaortic lymphnode metastasis of pancreatic cancer: paravertebral approach--a technical report with a case.

Paraaortic lymph nodal (PALN) recurrence is not a rare scenario of abdominal malignancies including pancreas cancer, even after radiotherapy. The role and indication of reirradiation is limited because it is often associated with significant late toxicity in the surrounding normal organs. We developed a new approach and technique of brachytherapy to overcome this difficult situation, with a paravertebral approach and hyaluronate gel injection (HGI). We encountered a patient with pancreatic cancer who developed PALN metastasis as in-field recurrence, 6 months after resection of pancreatic cancer with 50 Gy of preoperative radiotherapy. The applicator brachytherapy needles and gel injection needles were advanced by percutaneous paravertebral approach under local anesthesia, and by injection of a hyaluronate gel to separate the surrounding small intestines and the target. A single fraction of 18 Gy was delivered to the tumor (75.6 Gy equivalent in conventional schedule calculated with LQ model at α/β = 3) and total estimated D2cc (the minimum dose to the most irradiated volume of 2 cc, calculated at α/β = 2) in the small intestines was 61.6 GyE with HGI and 80.6 GyE without. No complications have been observed for six months. Three months later, FDG accumulation had disappeared, the tumor size was reduced, and serum CA-19-9 value decreased from 5150 U/mL to 36.6 U/mL (normal range < 37.5). Conclusively, the brachytherapy with the HGI procedure by paravertebral approach was thought safe and effective in reirradiation of PALN recurrence.