A large Danish follow-up study shows that using minimally invasive ablation to treat small and early stage kidney tumors can be as effective as more invasive surgery over time.

The standard of care for stage T1a renal cell carcinoma, where tumors are less than 4cm in diameter, is to cut them out surgically as well as a margin of tissue around the tumor. However, ablation therapy using heat or cold to destroy the tumor in place is becoming more common, particularly as diagnosis is occurring at an earlier stage.

Ablation is less invasive for patients, as a doctor places one or more thin probes through the skin and into the tumor under the guidance of computed tomography or ultrasound imaging rather than carrying out open surgery. The tumor is then most commonly destroyed by freezing it using cryoablation or applying heat using radiofrequency ablation.

“Previous studies have shown that patients treated with ablation have fewer complications, shorter hospital stays, and less decline in kidney function than patients who undergo tumor resection, positioning ablation as a less invasive option,” write lead author Iben Lyskjær, PhD, an associate professor at Aarhus University in Denmark, and colleagues in the article describing the work in the journal Radiology.

To try and collect more evidence about the efficacy of ablation versus more invasive surgery for treatment of early kidney cancer, the retrospective nationwide-registry cohort study carried out by Lyskjær and colleagues analyzed data from 1862 patients with T1a renal cell carcinoma diagnosed between 2013 and 2021. The group were aged 64 years on average and were mostly male (1305 patients).

Of the patients in the study, 540 underwent ablation of their tumors, 1002 had resection surgery to remove the tumor and 329 had the affected kidney removed. The patients were monitored until the end of 2023, and had between two and 10 years of follow-up.

The analysis showed no significant difference in progression risk between patients in the ablation group versus the surgical group. There was a slightly increased risk of local recurrence in the ablation group versus the resection group, at 2.4% versus 1.2%, respectively. But cancer metastasis risk was lowest in the ablation compared with the resection and nephrectomy groups at 1.7% versus 1.9% and 4.4%, respectively.

“Although the local recurrence rate was slightly higher in the ablation group, tumors that recur can be successfully treated with another ablation or surgery,” said Lyskjær in a press statement. “Importantly, patients in the study who had local recurrences did not have worse overall survival.”