Abstract: PD59-11
Sources of Funding: None

Introduction

The natural history of small renal masses (T1a) has been well defined leading to the recommendation of considering active surveillance as a viable option for the management of such masses in the elderly. Less clear, however, is the management of larger masses in such patients. The treatment of masses over 4 cm in the elderly and infirm is often contingent on a competing risk of death analysis with other comorbidities. The objective of this study is to define the natural history, including the growth rate and metastatic risk, of large and untreated renal masses in order to better council patients on their competing risks.

Methods

A search was conducted into the imaging database at our centre for renal masses between 2005 and 2016. The search results were then reviewed by a radiologist. Renal masses concerning for renal cell carcinoma by imaging measuring over 4 cm and that had at least 2 cross-sectional imaging studies greater than 6 months apart were included. The 3 dimensional measurements of each renal mass were performed by one radiologist. A retrospective review of each patient's clinical chart was also conducted. Growth rates of the maximal tumor dimension were calculated. 95% confidence intervals using t-test were completed. Metastatic rates, cancer specific and overall mortality were also evaluated.

Results

We found 68 patients who met the inclusion criteria. Mean age at study entry was 75.5 years, mean eGFR was 57.5 ml/min/1.73m2. Mean tumor maximal dimension at study entry was 5.6cm and mean follow up was 2.5 years. 46 patients did no develop metastasis during the follow-up period and showed a growth rate of 0.67 cm/year (95% CI: 0.34 cm/yr to 1 cm/yr). 15 patients (22%) developed metastasis during follow-up with a mean tumor growth rate of 0.98 cm/year (95% CI: 0.33 cm/yr to 1.63 cm/yr). 7 patients had metastasis at presentation and were not treated and they showed a growth rate of 1.47 cm/year (95% CI: 0.37 cm/yr to 2.57 cm/yr). _x000D_ 10 patients progressed to radical nephrectomy; 2 progressed to partial nephrectomy. 17 (25%) patients died of metastatic RCC, 17 (25%) died of other causes. Overall and cancer specific survival were 50% and 75%, respectively._x000D_

Conclusions

Large renal masses (> 4cm) have a higher growth rate than that reported for small renal masses. There is a tendency for the growth rate to increase in those who are likely to develop metastasis. Cancer specific survival in our cohort was 75% at a mean follow up of 2.5 years. Selection criteria for recommending observation of larger renal masses (>4cm) need to be more stringent than small renal masses reserving it only for much sicker and older patients. _x000D_ _x000D_

Funding

None