Cicatricial Changes in the Kidneys and Their Link to Renal Tumours. Summary of the Doctoral Thesis

Abstract

Over the last twenty years, the incidence of renal tumours has been increasing year on year by approximately 2%. A significant increase in tumour incidence can be seen in Latvia as well. In European countries, the overall mortality rates tend to decrease, while in Latvia the mortality rate is not decreasing. In accordance with data from the Centre for Disease Prevention and Control of Latvia, in 2012, the incidence of renal cancer in Latvia was 10.2 cases per 100,000 inhabitants (an 11% increase over seven years). So far, studies have not been carried out in Latvia into whether nephrosclerotic processes affect the incidence, morphological type and grade of renal tumours. Clear cell renal cell carcinoma, which accounted for 67.8% of the diagnosed tumours, was the most common morphological type of renal tumour in the present study. Renal oncocytary adenoma accounted for 9.9% of the cases, papillary renal cell carcinoma for 7.2% of the cases, and chromophobe renal cell carcinoma for 7.5% of the cases. When studying renal tissues adjacent to the tumours mentioned above, the author of the study found new tumors in them, and these were papillary renal adenomas (in 67 cases, or 22%), clear cell renal carcinomas (in 21 cases, or 6.3%), and oncocytary adenomas (in 10 cases, or 3.3%). There were pronounced nephrosclerotic changes in the tissues adjacent to these tumours, as well as cystic changes in the tubules. Also at the same time, while studying a group of kidneys with various degrees of nephrosclerosis, the author found that the most common tumours were papillary renal adenoma and clear cell renal carcinoma. In comparison to the control group, the author found that tumour incidence was 53 times higher among the group of nephrosclerotically altered kidneys and that the incidence of these tumors increased with greater severity of nephrosclerosis. Similarly, the author also found that in kidneys with tumours and nephrosclerosis, the incidence rates of the most common histological types of new tumours significantly differed from the incidence rates of histological types occurring randomly among the general population.This suggests that tumour initiating factors might have different effects on the emergence mechanisms of tumours of various histological types, and that these factors might also possibly affect prognostic factors. When comparing the immunohistochemical prognostic factor expression in three groups of different histological tumour types, differences were observed in prognostic factor expression in tumours of high levels and stages of malignancy. There was a different expression of protein p16 in the tumour groups with and without nephrosclerosis. An increased p16 expression in renal tumours with nephrosclerosis in adjacent tissues indicates a better prognosis. The author also observed changes in immunohistochemical reactions in nephrosclerotically altered kidneys outside of tumours, which suggests that background changes might play a role during the tumour formation stage. There is an increased risk of developing renal tumours in tissues altered by nephrosclerosis of any genesis type, and it increases rapidly when nephrosclerosis reaches more advanced stages.