Intensity modulation radiation therapy as alternative primary non‐surgical treatment of upper tract urothelial carcinoma

Abstract

DOI: 10.1111/iju.14166 According to the European Association of Urology, the most commonly accepted standard treatment for localized UTUC is RNU. Another procedure listed by many guidelines is a nephron-sparing surgical procedure whereby the tumor is removed, but the kidney is left intact. These methods are invasive and require general anesthesia, and might be unsuitable for patients in overall poor health, those with one kidney only or those with a high anesthesia risk unable to receive RNU or nephron-sparing surgery. For such patients, conservative treatment or palliative care is usually carried out. Currently, chemotherapy or chemotherapy combination radiotherapy is used for metastatic UTUC patients, and adjuvant therapy for locally advanced UTUC is used after RNU. Limited research has been carried out of local UTUC patients who are unsuitable for operation using chemotherapy or chemotherapy combination radiotherapy. In addition, because of impaired renal function and overall poor health, these patients were also not suitable for cisplatin-based chemotherapy, which is first-line chemotherapy for UTUC. The PTCOG 2017 Committees once reported that medically inoperable ureter cancer treated with carbon ion radiotherapy might be a useful treatment option. However, due to the limited research and accessibility to this expensive equipment, the cost-effectiveness and viability of carbon ion radiotherapy need to be considered. In a study sharing experience using SBRT to treat renal tumors, Staehler et al. reported the procedure to be safe and efficacious in the short-term. However, because SBRT requires large doses of radiotherapy in every fraction, it is important to minimize organ movement during treatment to reduce exposure to nearby organs. This might be difficult, because UTUC does not occur in the renal parenchyma, but in the renal pelvis and ureter, both close to the easily damaged small intestine. The dose must be large enough to treat the tumor, but low enough to protect nearby organs, especially the small intestine, making planning very difficult. Hence, we considered the use of IMRT as a possible primary radiotherapy option for patients with localized UTUC unsuitable for surgery. Between January 2012 and December 2015, 16 patients were diagnosed as having localized single lesion UTUC by ureteroscopy and abdominal CT, and were found to be unsuitable for surgery at Kaohsiung Medical University Hospital, Kaohsiung Taiwan. We only used IMRT to treat these patients. No chemotherapy or immunotherapy was used. The eligible patient was set-up in the supine position with their arms overhead. An abdominal immobilization device of either a thermoplastic cast or a vacuum bag was used to immobilize the patient during simulation and throughout the course of treatment. The renal pelvis tumor or ureter tumor was targeted. Target volume was expanded by 0.5 cm, and radiotherapy at the isodose line aimed at covering >95% of the target volume (Fig. 1a,b; Fig. S1). Radiotherapy was delivered 5 days/week, with a total dose of 70 Gy in 35 fractions within 2 months. Dose–volume histograms were created for nearby normal organs, with dose constraints set at Dmax <45 Gy, V30 Gy <120 cc, V20 <30%, V30 <30% and Dmax <40 Gy in the spinal cord, small intestine, functional kidney, liver and stomach, respectively (Fig. 1c,d; Table S1; Appendix S1). In these 16 patients, the mean age was 78 years (range 51–93 years), mean BMI 24.8 kg/m (range 16.2–34 kg/m) and mean eGFR before treatment 32.3 mL/min/ 1.73 m (range 12–56.3 mL/min/1.73 m). Six of the patients were men. A total of 13 patients were diagnosed as having a high-grade tumor using the World Health Organization grading system. Nine patients had tumors in the renal pelvis and seven had tumors in the ureter. Five of the patients had locally advanced invasive tumors extending beyond the genitourinary system or lymphadenopathy, as observed by abdominal CT scan.