A population based study on Kidney Cancer in Norway (2008 - 2013). Aspects of biopsy use, surgical treatment and outcome

Abstract

Aims: The aim of this study was to explore whole nation data, reveal trends and obtain updated numbers on kidney cancer (KC) treatment in the six-year period from 2008- 2013. The field of KC management has undergone substantial changes over the last few decades regarding surgical approaches, the use of pretreatment biopsies, surveillance and management of metastatic disease. We wanted to evaluate patient outcomes, and to see if new guidelines were implemented. Material and methods: Data on 4,449 patients diagnosed with KC (ICD10 code 64) was extracted from the Cancer Registry of Norway for all three articles. In Paper I, an analysis is performed on patients with data on biopsies (n=4,051). For Paper II, the data subset constitutes all patients with a surgically treated localized kidney cancer ≤7cm (n=2,420). Paper III includes all surgically treated Norwegian patients (n=3,273), both with localized and advanced disease, operated on in hospitals performing more than 4 KC surgeries/year. Results: Paper I: A renal mass biopsy (RMB) was performed in 20.2% of all patients. From the first to the second half of the study period, the use of RMB increased from 9.1 to 11.5 % for localized disease, and was doubled among patients for observation. Predictors of RMB were older patients, tumor < 4 cm, multiple tumors and second primary cancer. Fewer patients with metastatic disease were without histopathology verification in the second period. Those without RMB had poorer survival. The majority of biopsies were performed in patients who had a cytoreductive nephrectomy (CN), and CN was performed in 35% of all patients. Paper II: There was a 28% increase in surgically treated patients, with tumors ≤ 7 cm and the rates of partial nephrectomy (PN) increased, while the rate of radical nephrectomy (RN) decreased. PN was performed for 58% of tumors ≤ 4cm and for 14% of tumors 4.1-7cm. There was also an increase for minimally invasive (MIM) approaches. The regional differences in the distribution of PN and RN were less pronounced at the end of the study period. Furthermore, our results indicate a possible survival benefit for a patient undergoing PN vs. RN. Paper III: RN was performed in 69% of the patients and PN in 31%. Overall, the 30- day mortality (TDM) was 0.89%, whereas the rate for localized and metastatic disease was 0.73% and 2.6%, respectively. TDM was higher in older patients and lower for PN and MIM procedures. The odds ratio for TDM in a low-volumecompared to a high-volume hospital was 3.35 and 4.98 for patients with localized and metastatic disease, respectively Conclusion: These studies demonstrate that trends in KC diagnostics and treatment are in line with international recommendations, and that Norwegian urologists seem to adapt to changes in guidelines. Lastly, patient outcomes in regard to TDM are in line with previous reports.