Updated long‐term outcomes after carbon‐ion radiotherapy for primary renal cell carcinoma

Abstract

Long‐term oncological outcomes for primary renal cell carcinoma (RCC) treated with carbon‐ion radiotherapy (CIRT) are poorly understood. Patients with primary RCC were treated with 12 or 16‐fraction CIRT at The Hospital of the National Institute of Radiological Sciences outside of clinical trials. Outcome data were pooled and retrospectively analyzed for toxicity, local control, and disease‐free, cancer‐specific, and overall survival. From 1997 to 2014, 19 RCC patients (11 with T1aN0M0, 4 with T1bN0M0, and 4 with inoperable advanced stage [T4N0M0, T3aN1M0, and T1aN0M1]) were treated with CIRT and followed up for a median of 6.6 (range, 0.7‐16.5) years; 9 of these patients were inoperable because of comorbidities or advanced‐stage disease. Diagnoses were confirmed by imaging in 11 patients and by biopsy in the remaining 8. In 4 of 5 patients with definitive renal comorbidities, including diabetic nephropathy, sclerotic kidney or solitary kidney pre‐CIRT progressed to grade 4 chronic kidney disease (CKD). In contrast, the remaining 14 patients without definitive renal comorbidities did not progress to grade 3 or higher CKD. Furthermore, although 1 case of grade 4 dermatitis was observed, there were no other grade 3 or higher non‐renal adverse events. Local control rate, and disease‐free, cancer‐specific, and overall survival rates at 5 years of all 19 patients were 94.1%, 68.9%, 100%, and 89.2%, respectively. This updated retrospective analysis based on long‐term follow‐up data suggests that CIRT is a safe treatment for primary RCC patients without definitive renal comorbidities pre‐CIRT, and yield favorable treatment outcomes, even in inoperable cases.

Carbon Ion Therapy: A Modern Review of an Emerging Technology

“…CIRT has been used with good efficacy and safety for the treatment of primary renal cell carcinoma. The NIRS experience reported on 19 patients treated with 12 or 16 fractions CIRT, with 5-year cancer specific survival (100%) and LC rates (94.1%) (85). A non-randomized phase I/II study determined that 72 GyE was well-tolerated, with no dose limiting toxicity.…”

Proton Therapy for Primary Renal Cell Carcinoma: The First Nationwide Retrospective Study in Japan

“…Furthermore, the studies using a BED 10 range of 60-80 Gy with a median follow-up for ≥2 years reported a relatively low local control rates (range=85.7-89%) as shown in Table III (24,25). Conversely, local control rates in all the 3 studies and the in vivo 34: 2883-2889 (2020) present study using a BED 10 ≥90 Gy with a median followup of ≥2 years were higher than 90% (11,12,23). Taking the previous reports of SBRT and particle beam therapy together, BED 10 ≥90 Gy may be necessary and high-dose RT using advanced technology can accomplish good local tumor control.…”

“…Correa et al reported the latest systematic review of RT for RCC and showed a rate of grade 3/4 adverse events of 1.5% and an eGFR reduction of 7.7 ml/min after using mainly photon SBRT (10). On the other hand, Kasuya et al reported that renal function after carbon ion RT was maintained in all 14 patients evaluated, without pre-treatment definitive renal comorbidities, and the average reduction in the eGFR was 6.1 ml/min/1.73 m 2 (12). Taken together, PBT can be used without inflicting any severe damage to the body, including renal function, and appears to be sufficiently safe.…”

“…However, an analysis of nine international multi-institutional studies of SBRT using a BED 10 range of 80-87.5 Gy reported a 4-year local control rate of 97.8% (20). Table III summarizes the clinical outcomes of previous studies evaluating RT for primary RCC (8,11,12,(22)(23)(24)(25). Those studies used a wide range of dose fractionation schedules and BED 10 values (range=38-125 Gy), but local tumor control was achieved in almost all patients irrespective of the BED 10 .…”

“…Regarding particle beam therapy, carbon ion RT showed 5-year and 10-year overall survival (OS) rates of 89.2% and 58.7% in 19 patients, respectively (12). Proton beam therapy (PBT), which is another type of particle beam therapy, has since long been used to treat various cancers (13)(14)(15)(16), but there are no clinical reports of its use for RCC.…”