A preliminary study published in The Journal of Urology, an Official Journal of the American Urological Association, found that for patients with early-stage renal cell carcinomas (RCCs) measuring 3 to 4 centimetres, a procedure called cryoablation that destroys cancer by freezing yields a lower risk of cancer-related death compared to heat-based thermal ablation (AUA). Wolters Kluwer publishes the journal as part of the Lippincott portfolio.

"In contrast, for patients with RCCs smaller than 3 centimetres, either cold-based or heat-based therapy is just as effective in reducing cancer-specific mortality," comments lead author Gabriele Sorce, MD, of IRCCS San Raffaele Scientific Institute, Milan.

"The findings may help us to better tailor the choice of ablation technique for patients with small RCCs." Cryoablation has a lower risk of cancer death than heating.

The most frequent type of kidney cancer is renal cell carcinoma. For patients with early-stage RCCs less than 4 cm in size, freezing or heating the tumour is an increasingly common therapy option. This cancer-destroying therapy, known as ablation, can provide high survival rates for patients with clinical stage T1a RCCs without the need for more comprehensive kidney surgery.

However, ablation appears to be "less beneficial" for a subset of individuals with clinical stage T1a RCCs whose tumours are between 3 and 4 cm in size.

For these malignancies measuring 3 to 4 cm, current European guidelines advocate cryoablation over heat-based thermal ablation, although US guidelines state that either treatment can be employed. Both sets of guidelines state that either freezing or heating can be used for T1a RCCs measuring 3 cm or smaller.

A multinational research team examined patients with stage T1a RCCs treated with freezing or heating between 2004 and 2018. Patients were taken from the Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute in the United States.

The study focused on two matched groups of patients with tumours measuring 3 to 4 cm in size: 757 who had cryoablation and 388 who received heat-based thermal ablation.

The median age at the time of therapy was 71 years. For 422 patients treated with freezing and 238 treated with heating, follow-up data on cancer-specific mortality - the risk of dying from kidney cancer excluding other causes of death - were available.

Eight years following treatment, the estimated cancer-specific mortality rate for individuals with RCCs measuring 3 to 4 cm treated with cryoablation was 8.5 per cent against 12.9 per cent for those treated with heat-based thermal ablation. In both cases, approximately 40 per cent of patients died from causes other than cancer.

Treatment implications for small, potentially curable kidney tumours

Patients having heat-based thermal ablation for RCCs between 3 and 4 cm were twice as likely to die of kidney cancer after controlling for non-cancer-related death and other factors.

In contrast, for patients with tumours less than 3 cm in size, the predicted cancer-specific mortality was comparable between groups: 6.8 per cent after cryoablation and 6.1 per cent following heat-based thermal ablation.

The study is one of the first to directly compare clinical outcomes for freezing versus heating in patients with stage T1a RCCs measuring between 3 and 4 cm.

The results suggest that heat-based thermal ablation has "a highly statistically significant and clinically meaningful" disadvantage in terms of the long-term risk of death from kidney cancer, compared to cryoablation.

"Conversely, in patients with tumour size 3 centimetres or smaller, either ablation technique is equally valid," says Dr Sorce. "We believe our findings have important implications for clinical decision-making and informed consent for patients with these small, potentially curable kidney cancers."