About the study

RAPSTAR is a phase III randomized, open-label clinical trial comparing two treatment approaches for localized renal cell carcinoma: robotic-assisted partial nephrectomy (RAPN) and stereotactic ablative radiotherapy (SABR).

The primary objective is to assess preservation of kidney function after treatment, measured by changes in estimated glomerular filtration rate (eGFR). The study aims to determine which approach better protects renal function while maintaining oncological effectiveness.

Why does it matter?

Renal cell carcinoma is the most common type of kidney cancer. In localized disease, treatment decisions are no longer focused only on tumour control. Preserving kidney function, reducing treatment burden and maintaining quality of life are also essential.

Partial nephrectomy remains the standard treatment for many localized kidney tumours, but surgery may be associated with complications, recovery time and possible deterioration of kidney function. SABR is a non-invasive approach that delivers a high dose of radiation very precisely to the tumour while limiting exposure of healthy kidney tissue.

To date, RAPN and SABR have not been directly compared in a randomized phase III trial in patients eligible for surgery. RAPSTAR aims to generate evidence that may help define the optimal treatment strategy for localized kidney cancer.

Treatment approaches compared in the study

Key features of the project

• the first randomized phase III trial directly comparing RAPN and SABR in localized kidney cancer;
• kidney function preservation as the primary study endpoint;
• evaluation of oncological outcomes, quality of life and cost-effectiveness;
• use of multiparametric MRI as a treatment-response biomarker;
• circulating tumour DNA (ctDNA) analysis for disease monitoring and recurrence prediction;
• multidisciplinary collaboration involving urology, radiation oncology, diagnostic imaging, nuclear medicine, biostatistics and health economics.

Study population

The study plans to enroll 164 adult patients with biopsy-confirmed renal cell carcinoma, a single kidney lesion and stage I disease. Participants will be randomized in a 1:1 ratio to one of two treatment arms: RAPN or SABR.

Eligibility is assessed individually, based on medical documentation, physician evaluation and the study protocol criteria.

What will be assessed?

The primary endpoint is preservation of kidney function after treatment compared with baseline. The study will also assess overall survival, local control, quality of life and treatment costs.

RAPSTAR also includes advanced imaging and molecular analyses, including multiparametric MRI, radiomic analyses and ctDNA assessment. These tools may help monitor treatment response and predict the risk of recurrence.

Quality of life

In addition to clinical and oncological outcomes, RAPSTAR evaluates how each treatment affects patients’ daily functioning, recovery and overall well-being.

Quality of life will be assessed using validated EORTC questionnaires, allowing researchers to compare the impact of surgery and stereotactic radiotherapy from the patient’s perspective.

Organizational information

The project is funded from the state budget by the Medical Research Agency (MRA). The study is conducted by the Medical University of Gdańsk and Nicolaus Copernicus University in Toruń in a multicentre collaboration.

• study type: randomized, open-label phase III clinical trial;
• planned enrollment: 164 patients;
• allocation ratio: 1:1 – RAPN or SABR;
• planned recruitment period: approximately 4 years;
• clinical follow-up: approximately 2 years after recruitment completion;
• funding value: approximately PLN 24 million.