Radiotherapy or Cryoablation (Freezing Treatment) for Early-Stage Kidney Cancer?

Kidney cancers account for approximately 3% of all cancers, and more than 90% of these cases are classified as renal cell carcinoma (RCC) . RCC incidence increases by approximately 2% annually worldwide, particularly in developed countries. Approximately two-thirds of patients have localized or locally advanced disease at diagnosis, meaning that the tumor is confined to the kidney or may have spread to nearby lymph nodes. Surgery is the most common and effective treatment for these patients.

However, approximately 20-30% of patients with RCC may be unsuitable for surgery. It can be risky for older patients, those with serious comorbidities, or those with severely impaired kidney function. Minimally invasive or noninvasive ablative treatments are therefore increasingly important. Alternatives for patients with localized RCC who cannot undergo surgery include radiofrequency ablation (RFA), microwave ablation, cryoablation, and the newer option of stereotactic body radiotherapy (SBRT). SBRT is also described as precisely targeted radiation treatment .

Ablation is particularly preferred for small tumors (<4 cm), although it has also been considered effective for larger tumors (≥4 cm) in recent years. SBRT is a newer noninvasive approach attracting attention because of its high local control rates in larger tumors. How do these approaches compare?

Lancet Analysis Suggests Greater Effectiveness With SBRT

Lancet Oncology published a meta-analysis in March 2025 suggesting that SBRT is as safe as other ablative treatments and potentially more effective as an option.

Dr. Srinivas Raman and colleagues from the Department of Radiation Oncology at Princess Margaret Cancer Centre in Toronto, Canada, wrote: “Our findings suggest that SBRT provides higher local control rates, particularly for larger tumors, and may have lower rates of serious complications than other ablative methods.”

Experts who emphasize a greater role for SBRT in early-stage RCC also support these findings. Radiation oncologist Prof. Shankar Siva of the Peter MacCallum Cancer Centre said: “With its noninvasive nature, low toxicity, and advantages in preserving kidney function, SBRT should be adopted more widely.”

The analysis provides strong data for multidisciplinary kidney tumor boards to consider SBRT as an alternative to other ablative techniques.

Renal Cell Carcinoma and Treatment Options

Available ablation techniques include:

• RFA and microwave ablation: Minimally invasive thermal ablation methods that destroy tumors using heat.

• Cryoablation: A method that freezes and kills tumor cells using extreme cold.

US and European guidelines recommend these treatments particularly for tumors smaller than 4 cm.

What Does the Meta-Analysis Show?

Dr. Raman's team systematically reviewed 8910 patients treated for localized RCC across 133 studies in a meta-analysis. The patients' mean age was 68.

• 1-year local control rates: Cryoablation 95%, SBRT 99%

• 2-year local control rates: Cryoablation 94%, SBRT 97%

• 5-year local control rates: SBRT 95%, RFA 92%, cryoablation 90%, microwave ablation 86%

SBRT had the highest local control rates particularly in tumors larger than 4 cm:

• SBRT: 93%

• RFA: 79%

• Microwave ablation: 82%

• Cryoablation: 85%

Cancer-specific survival:

• 1 year: 100% across all treatments

• 5 years: Small tumors: SBRT and RFA 100%, microwave ablation 97%, cryoablation 98%

• Large tumors: Microwave ablation 100%, SBRT 95%, cryoablation 94%

Patients treated with SBRT were older and had larger tumors than those receiving other ablative methods, both factors associated with a less favorable disease course. Despite this, SBRT maintained high effectiveness even at 5 years of follow-up.

SBRT in Clinical Practice

Despite these strong findings, SBRT remains relatively underused. The meta-analysis also found it to be the least commonly used ablative method:

• Cryoablation: 3726 patients

• RFA: 2503 patients

• Microwave ablation: 2069 patients

• SBRT: 612 patients

Prof. Siva said: “The impressive efficacy and safety data support wider use of SBRT in patients with early-stage RCC who are unsuitable for surgery. It provides excellent long-term local control, particularly for large tumors.” The FASTTRACK II study led by Siva achieved, in patients with a median tumor size of 4.6 cm, 100% local control after SBRT, with no cancer-related deaths.

Conclusion and Commentary

The findings suggest that SBRT deserves increasing consideration as a strong option for localized RCC. High local control and a low risk of serious complications make it an important alternative, particularly for patients who cannot undergo surgery or have large tumors. The meta-analysis shows the best local control outcomes with SBRT even over follow-up extending to 5 years. Nevertheless, it remains less widely used than other ablative techniques, and reservations about clinical adoption persist.

The choice of ablative treatment depends on patient characteristics, tumor size, access, clinician experience, and other factors. Although SBRT has clear advantages, large randomized controlled trials are needed to clarify critical outcomes such as long-term survival and metastasis rates. More research is also needed to establish its role in patients suitable for surgery.

Future studies should examine not only oncological efficacy but also cost-effectiveness, quality of life, and overall health outcomes. In appropriately selected groups, SBRT could become a strong standard for patients with RCC who cannot undergo surgery. Wider acceptance in clinical practice, however, requires multidisciplinary assessment and further evidence.