Renal cell carcinoma: prognostic significance of incidentally detected tumors.

PURPOSE: We determined the prognostic significance of incidentally discovered renal cell carcinoma in the era of increased incidental detection.
MATERIALS AND METHODS: We reviewed the records of 633 consecutive patients who underwent radical or partial nephrectomy for renal cell carcinoma at our institution between 1987 and 1998. Patients were divided into those who were asymptomatic and tumor was diagnosed incidentally and those diagnosed after presenting with any of the classic symptoms of renal cell carcinoma or subsequent metastasis. All renal cell carcinoma lesions were assigned a stage and grade according to 1997 TNM criteria. All patients were followed postoperatively to assess survival rates, and monitor recurrence and metastasis.
RESULTS: Of the 633 patients 95 (15%) were treated for incidentally discovered renal cell carcinoma and 538 (85%) presented with symptoms secondary to renal cell carcinoma at diagnosis. Patient age and sex distribution were similar in the 2 groups. Stage I lesions were observed in 62.1% of patients with incidental renal cell carcinoma and in 23% with symptomatic renal cell carcinoma. In contrast, stage IV lesions were present in 27.4% of patients with incidental versus 54% with symptomatic renal cell carcinoma. Thus, incidental lesions were of significantly lower stage than those causing symptoms (p <0.001). Similarly 15.8% of incidental but 42.4% of symptomatic lesions were grade 3 or 4 (p = 0.006). Patients were followed postoperatively for a mean of 47 months plus or minus 40 months. The 5-year cancer specific survival rate was significantly higher for incidental than for symptomatic tumors (85.3% versus 62.5%). Likewise, the local and distal recurrence rates were higher for symptomatic lesions. When adjusted for stage, no difference in survival was noted in the 2 groups for stages I to III disease and a minimally significant difference was noted for stage IV cancer. Multivariate analysis of stage and grade attributed the survival difference in stage IV disease to the significantly higher grade of symptomatic lesions.
CONCLUSIONS: At presentation incidental tumors are of significantly lower stage and grade than tumors producing symptoms. Subsequently these clinically and histologically less aggressive lesions lead to better patient survival and decreased recurrence. Thus, the detection of renal cell carcinoma before symptom onset enables treatment of less aggressive tumors and provides a better prognosis for patients. Given these data efforts should be directed toward the development of a screening protocol to detect these lesions early, so that they may be prevented from progressing to the point when symptoms are apparent and prognosis becomes worse. In addition, the significant correlation of tumor grade with survival in our study further demonstrates the prognostic value of tumor grade and molecular markers for the future evaluation and treatment of renal cell carcinoma.