Continued growth of a kidney tumor after previously performed stereotactic radiation therapy

Abstract

Background. Until recently, kidney cancer was considered "radioresistant" in the context of traditional fractionated radiotherapy. However, the ability to accurately deliver high doses using stereotactic radiotherapy (SBRT) has changed this paradigm, and today its use has found its niche for patients who are denied surgery for one reason or another. Objective. To evaluate the results of overall survival and local control after the use of stereotactic radiotherapy (SBRT) in the treatment of inoperable patients with stage I kidney tumor, to assess the level of renal toxicity. Materials and methods. This study included 60 patients with verified kidney tumor who received SBRT courses at the State Autonomous Healthcare Institution "ChOKTsO i NM" in the period from 2011 to 2024. The average age of patients was 70±8.6 years (from 49 to 93). The ratio of men and women was 1:1. In 51 cases, STLT was performed on the primary tumor, in 8 cases - for recurrent kidney cancer after previous surgical treatment, including 1 patient - for recurrent cancer of both kidneys. The treatment was performed on the CyberKnife device with a total focal dose (TFD) of 30 to 45 Gy in 3 fractions. Results and discussion. The median overall survival (OS) was not reached, since most patients remain censored. The one-year OS rates were 97%, 5-year 68%, one-year progression-free survival (PFS) - 95%. In the analysis of local control, 7 patients (11.6%) showed a complete response according to RECIST 1.1 criteria, half of the patients (31 patients - 51.7%) showed stabilization of the process, in 28.4% of cases (17 patients) - a partial response, in 8.3% (5 cases) - progression of the process. As part of this study, a thorough analysis of patients with continued tumor growth after a course of STLT was carried out. The median occurrence of continued growth was 14 months (from 11 to 111 months). The initial size of the kidney tumor in these patients averaged 45 cm3 (from 21 to 80 cm3). In most cases (n = 3; 60%), a total focal dose of 45 Gy was administered. According to the RECIST1.1 criteria, the increase in the size of the tumor focus ranged from 28% to 80%. A decrease in the glomerular filtration rate and, as a consequence, renal excretory function was noted in 25% of patients 6 months after the treatment, but 2 years after the completion of STLT, renal function was completely restored in all cases. Conclusion. Conducting STLT in inoperable patients with local stages of kidney tumor allows achieving a high level of local control and is accompanied by the development of moderate renal toxicity.

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