Application of cyberknife in treatment of retroperitoneal lymph node metastatic tumors in 81 cases

Abstract

Objective To evaluate the clinical efficacy and side effects of cyberknife therapy in the treatment of retroperitoneal lymph node metastatic tumor. Methods Among the 81 patients presenting with postoperative retroperitoneal lymph node metastases, 33 cases suffered from abdominal pain or low back pain, 7 had unilateral hydronephrosis and ureteral dilatation, and 8 developed unilateral or bilateral lower limb swelling. Using stereotactic radiotherapy with a cyberknife, DT was delivered at 33-45 Gy/3-6 F. The improvement of symptoms, objective tumor response rate, and irradiation-induced side effects were observed. Results At 4 weeks after treatment, pain and swelling of the lower extremities were completely mitigated, and hydronephrosis was fully healed in all patients. Enhanced CT or MRI was performed every 2 to 3 months. After 6-month follow-up, the complete response (CR) rate was calculated as 77%(62/81), 21%(17/81) for the partial response (PR) rate, 3%(2/81) for the stable disease (SD) rate and the effective rate (CR+ PR) was 98%.No case progressed. The main side effect was intestinal injury, including grade 1 in 16%(13/81), grade 2 in 9%(7/81). Multivariate analysis demonstrated the CR rate was not correlated with the type of the primary tumor or the size of the tumor (P>0.05), but was significantly associated with the distance of>0.5 cm between the tumor and intestine and the BED (α/β=10)>70 Gy of the tumor irradiation (P 5 cm and the distance of<0.5 cm between the tumor and intestine (P<0.01). Conclusion Cyberknife is an efficacious and safe approach in the treatment of retroperitoneal lymph node metastatic tumors. Key words: Retroperitoneal lymph node metastatic neoplasms/stereotactic radiotherapy; Radiotherapy, cyber knife