Clinical T1a Renal Cell Carcinoma, Not Always a Harmless Disease-A National Register Study.

Background: T1a renal cell carcinoma (RCC) is typically considered a curable disease, irrespective of the choice of local treatment modality. Objective: To identify factors associated with the risk of local and distant recurrence, and overall survival (OS) in patients with primary nonmetastatic clinical T1a RCC. Design setting and participants: A population-based nationwide register study of all 1935 patients with cT1a RCC, diagnosed during 2005-2012, identified through The National Swedish Kidney Cancer Register, was conducted. Outcome measurements and statistical analysis: Outcome variables were recurrence (local or distant) and OS. Possible explanatory variables included tumor size, RCC type, T stage, surgical technique, age, and gender. Associations with disease recurrence and OS were evaluated by multivariable regression and Cox multivariate analyses, respectively. Results and limitations: Among 1935 patients, 938 were treated with radical nephrectomy, 738 with partial nephrectomy, and 169 with ablative treatments, while 90 patients had no surgery. Seventy-eight (4%) patients were upstaged to pT3. Local or metastatic recurrences occurred in 145 (7.5%) patients, significantly more often after ablation (17.8%). The risk of recurrence was associated with tumor size, upstaging, and ablation. Larger tumor size, disease recurrence, and older age adversely affected OS, whereas partial nephrectomy and chromophobe RCC (chRCC) were associated with improved survival. Limitations include register design and a lack of comorbidity or performance status data. Conclusions: Upstaging and recurrence occurred, respectively, in 4.0% and 7.5% of patients with nonmetastatic RCCs ≤4 cm. Tumor size upstaging and ablation were associated with the risk for recurrence, while tumor size and recurrence were associated with decreased OS. Patients with chRCC and partial nephrectomy had prolonged OS in a real-world setting. Patient summary: We studied factors that may influence the risk of disease recurrence and overall survival, in a large nationwide patient cohort having nonmetastatic renal cell carcinoma ≤4 cm. Tumor size, tumor type, and treatment were associated with the risk of recurrence and overall death. Partial nephrectomy prolonged overall survival.