FASTRACK II: High-Dose Radiation Effective in Older Patients With Inoperable Kidney Tumors

Older adults who are diagnosed with kidney tumors that are not suitable for surgery may benefit from targeted, high-dose radiation, according to results of the multi-institutional phase 2 Trans-Tasman Radiation Oncology Group Focal Ablative Stereotactic Radiotherapy for Cancers of the Kidney (FASTRACK II) study.

Results of FASTRACK II were presented at the American Society for Radiation Oncology 2023 Annual Meeting.

While previous single-institution studies have shown promise for stereotactic radiation treatments in patients with inoperable kidney tumors, FASTRACK II is the first study to assess the efficacy of stereotactic ablative body radiotherapy (SABR) in a large, multi-institutional clinical trial. The nonrandomized, prospective study sampled 70 patients with inoperable, high-risk tumors. Patients received SABR in 1 or 3 sessions at 7 Australian centers and 1 center in the Netherlands.

Patients with tumors smaller than 4 cm (n=23) received a single fraction of radiation, and those with tumors larger than 4 cm (n=47) received 3 fractions.

After a median follow-up of 43 years, researchers reported that none of the patients experienced local progression, nor did any patients die from cancer. Overall survival 1 year after SABR was 99%, and it was 82% after 3 years. Only 1 patient experienced a distant recurrence of their cancer.

Additionally, they noted that side effects were “relatively modest,” with no grade 4 or 5 toxicities observed. Fifty-one patients (73%) had a grade 1-2 treatment-related adverse event, and 11 patients (16%) experienced no adverse events. Only 1 patient required dialysis following treatment.

“Our study demonstrated that a novel treatment delivered in an outpatient setting is able to achieve unprecedented efficacy for patients with inoperable kidney cancer,” said lead study author Shankar Siva, PhD, a radiation oncologist at the Peter MacCallum Cancer Centre. “There’s an unmet need for curing this type of cancer, and our findings point to the potential of radiation therapy to address that need.”

Dr. Siva credited rigorous quality control and the effectiveness of stereotactic radiation for the high efficacy rate and preserved kidney function observed in the trial. He added that there is a need for a further phase 3 trial to compare stereotactic radiation versus surgery as the optimal treatment option for patients with inoperable kidney cancer.

“Given a choice between the 2, I believe a lot of patients would opt for noninvasive radiation,” he said.