Active monitoring of contrast-accumulating kidney tumours
Authors: Keln A. A. , Schmidt S. S. , Kupchin A. V. , Berdichevsky B. A. 
Published: December 2020

Introduction. The incidence of kidney cancer (KC) in the world is increasing and today is about 3%, but the death rate from this type of malignancy does not increase proportionally. According to research by many authors, more than half of the patients are over 65 years old at the time of diagnosis. Patients at this age have a high incidence of high comorbidity and risk of death from cardiovascular or other intercurrent pathology that exceeds the risk of death from KC. Recently, there has been a positive trend in the detection of the disease in the early stages up to 61.80%. Most of the primary detected kidney tumours are diagnosed randomly as asymptomatically small (less than 4 cm) tumours without signs of visceral metastasis. These tumours have a high degree of differentiation and rarely require surgical treatment in addition to their small size, and in the case of surgery, these pathomorphological results are benign. Due to the slow progredient growth of kidney formations and an asymptomatic course, the method of dynamic observation of kidney tumours is relevant in elderly patients and avoids unnecessary risks of surgical treatment of localized KC.Purpose of the study. To trace the growth rate of kidney tumours accumulating contrast agent using the method of dynamic observation. This study will allow us to differentially approach the choice of surgical treatment, which is optimal for elderly patients with low somatic status.Materials and methods. In the Multidisciplinary clinical medical centre «Medical City» (Tyumen) database all cases of radiographically verified space-occupying lesions of the kidneys that accumulate contrast were selected in the period from 2009 to 2019. We studied 50 people: 23 women (46%) and 27 men (54%), aged from 58 to 90 years. The study group included patients with kidney neoplasms of size < 7cm. Patients whose follow-up period was less than 12 months were excluded from the analysis. Regularly, every 3 to 6 months, patients underwent computed tomography to assess the growth dynamics. The size of the tumour, which was assumed to be its diameter in the largest dimension, was carefully studied. The growth rate of the tumour was calculated as the average change in diameter for 1 year during the entire observation period.Results. The average age of patients was 74.8 ± 7.4 years according to the results of the study. The age of patients at the time of diagnosis also had no prognostic significance for the rate of growth of kidney tumours (p > 0.05). The primary diagnosis was made in 32 patients (64%) using CT, in 18 (36%) using ultrasound. The average size of the tumou at the time of detection was 35.0 ± 6.9 mm. Percutaneous kidney biopsy was performed in 2 patients for morphological verification of the tumour type. Moderate-differentiated light-cell renal cell carcinoma pT1bN0M0 was detected in both patients according to the results of histological differentiation. The average linear growth rate of the tumour was 6.6 ± 2.4 mm / year. The size of the tumour at the time of diagnosis was not correlated with the growth rate (p > 0.05). There was no correlation between the rate of increase in the size of formations depending on their structure — solid (median 6 mm / year; average — 10 mm / year) or cystic-solid (median 7 mm / year; average 9 mm / year; p > 0.05). The absence of tumour growth dynamics during the entire observation period was detected in 22 (44%) people, including 10 (20%) men and 12 (24%) women. Visceral metastasis was diagnosed in 3 cases: to the liver, spleen, and the appearance of a second tumour on the contralateral kidney. Surgical treatment was performed in 4 patients (8%), in 2 (4%) cases, the indication for surgery was the progression of the tumour in the form of the appearance of visceral metastases. One patient had chromophobic KC pT1bN0M1, the other had renal cell carcinoma, a light-cell variant of pT1bN0M1. The operation in the volume of kidney resection was performed in 2 (4%) patients, in both cases, morphologically confirmed renal cell carcinoma, light-cell variant pT1aN0M0. The presence of a cystic-solid component and the initial size of the tumour were potential radiographic signs that could predict the dynamics of an increase in renal parenchyma neoplasm.Conclusion. The tactic of actively observing the growth rates of kidney tumours that accumulate contrast material allowed us to better understand the biological behaviour of KC. It was found that most kidney malignancies have a slow growth rate when determining the linear growth rate of the tumour. This conclusion allows us to differentially approach the choice of surgical treatment, which is optimal for elderly patients with low somatic status. Because prognostic signs of KC have not yet been identified and are not fixed in international treatment protocols, all patients who are suitable candidates for surgery are shown operative treatment.