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Stereotactic ablative radiotherapy for renal cell carcinoma safe in patients with solitary kidney
Stereotactic ablative radiotherapy for renal cell carcinoma produced comparable outcomes among patients with solitary and bilateral kidneys, according to findings presented at the American Society for Radiation Oncology Annual Meeting.
“Stereotactic ablative radiotherapy is actually an emerging treatment for renal cell carcinoma,” Rohann J.M. Correa, MD, PhD, a radiation oncology resident at London Health Sciences Center in London, Canada, said at a press conference. “Solitary kidney renal cell carcinoma represents a unique situation and a challenging management scenario. Patients are at high risk for renal dysfunction due to prior nephrectomy. There is a lack of renal function reserve.”
Correa and colleagues sought to compare oncologic outcomes and renal function among patients with solitary kidneys and bilateral kidneys who underwent stereotactic ablative radiotherapy.
Management options for patients with solitary renal cell carcinoma tend to be invasive and limited, according to Correa. “Stereotactic ablative radiotherapy, on the other hand, is a noninvasive, outpatient strategy,” he said.
Mark A. Hallman, MD, PhD, assistant professor in the Department of Radiation Oncology at Fox Chase Cancer Center and another investigator on the study, added that any option for this patient population comes with risk. “Both surgical resection and stereotactic ablative radiotherapy pose the potential risk of complications, including renal failure requiring dialysis,” Hallman told HemOnc Today.
The cohort included 223 patients from nine centers in Australia, Germany, Japan and North America. Among them were 81 patients (mean age, 62.5 years; 69% male) with solitary kidneys who underwent renal stereotactic ablative radiotherapy.
Baseline data show 97.5% of patients had an ECOG status of 0-1, and 14.8% (n = 12) had metastatic disease.
Pathological confirmation was obtained from 91.4% of the cohort, revealing a median tumor diameter of 3.7 cm (interquartile range, 2.5-4.3) among patients with solitary kidneys and 4.3 cm (IQR, 3-5.5) among patients with bilateral kidneys (P < .001).
Patients received a median radiotherapy dose of 25 Gy (range, 14-70) in a median fraction of 1 (range, 1-10).
Both total dose and number of fractions were significantly lower among patients with solitary tumors (P .001). However, there was no difference reported in median biologically effective dose between the two groups, with patients in the solitary group receiving 87.5 Gy (range, 33.6-125) and those in the bilateral group receiving 87.5 Gy (range, 37.5-125; P = .103).
Mean eGFR at baseline was higher among the solitary kidney group (64.6 ± 21.7 mL/min) than the bilateral group (57.2 ± 21.6 mL/min; P = .016). Declines in mean eGFR following stereotactic ablative radiotherapy were similar among the solitary group (-5.8 mL/min) and bilateral group (-5.3 mL/min; P = .984).
Follow-up data through 2.57 years indicated a local control rate of 98%, a PFS rate of 77.5%, a cancer-specific survival rate of 98.2%, and a 2-year OS rate of 81.5%. There was one local failure in the solitary kidney group and two local failures in the bilateral group.
“These results are comparable to similar series of partial nephrectomy,” Hamilton said.
Univariable analysis results from the solitary kidney group revealed an association between moderate chronic kidney disease — defined as eGFR of at most 60 mL/min — and poorer PFS (HR = 2.66, P = .043).
No solitary kidney patients required dialysis, compared with six (4.2%) in the bilateral cohort.
“These data pose stereotactic ablative radiotherapy as an effective and relatively safe option for treatment of early stage renal cell carcinoma in a solitary kidney, particularly among inoperable patients,” Hamilton said.
“We conclude that stereotactic ablative radiotherapy can provide excellent local control with acceptable impact on renal function in patients with a solitary renal cell carcinoma,” Correa said. “We suggest a referral for kidney stereotactic ablative radiotherapy is worthy of consideration in this population.” — by Rob Volansky
Reference:
Correa RJM, et al. Abstract 222. Presented at: American Society for Radiation Oncology Annual Meeting; Oct. 21-24, 2018; San Antonio.
Disclosures: Correa reports no relevant financial disclosures. Hallman reports consulting for New Century Health.
Perspective
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Impaired kidney function and dialysis can significantly impact the health and survival of patients whose renal cell cancer may otherwise have a long natural history. In the especially vulnerable solitary kidney population, kidney-sparing treatment approaches are obviously advantageous. Correa and the IROCK group have assembled a growing international cohort of patients with renal cell carcinoma treated safely and effectively with stereotactic radiation. Remarkably, none of the 81 patients with a single kidney in this cohort required dialysis after stereotactic ablative radiotherapy. On the contrary, disease control and kidney function were excellent and comparable to results seen in patients with both kidneys intact. This work is an important step forward and has meaningful health and quality-of-life implications for patients with renal cell carcinoma. As evidence continues to mount behind the tolerability and efficacy of stereotactic ablative radiotherapy in renal cancer, one hopes the oncology community will consider wider adoption of this patient-friendly approach in appropriate individuals, who now include patients with a solitary kidney.