Abstract
BACKGROUND
A proportion of patients diagnosed with pathologic T1 (pT1) clear cell renal cell carcinoma (CC‐RCC) will experience disease progression and death after surgery, whereas the majority remain disease free. The authors conducted a case–cohort investigation to examine the association of insulin‐like growth factor I receptor (IGF‐IR) expression and disease‐specific survival in patients who underwent surgery for pT1 CC‐RCC.
METHODS
Eligible patients included those diagnosed with solitary, nonfamilial pT1 CC‐RCC who underwent radical nephrectomy at the Mayo Clinic‐Rochester between 1970 and 2000 (n = 886 patients). Among this group, 136 patients died of CC‐RCC (cases). Archived tumor blocks were not available for 62 patients, leaving a final study group of 74 cases. Stratified, random sampling was used to select a cohort of at least 3 year‐matched controls (no CC‐RCC death) for each case (n = 263 patients). Detection of IGF‐IR was performed using a commercially available monoclonal antibody. Cox proportional hazards models were fit to assess the association between IGF‐IR expression and disease‐specific survival.
RESULTS
After adjustment for age, the risk of death from CC‐RCC was greater for patients who had tumors that stained positive for IGF‐IR compared with patients who had tumors that showed no IGF‐IR expression (hazard ratio [HR], 1.5; 95% confidence interval, [95% CI], 0.9–2.4). In a stratified analysis, the risk was stronger among patients who had high‐grade tumors (HR, 2.2; 95% CI, 1.1–4.3) compared with patients who had low‐grade tumors (HR, 0.7; 95% CI, 0.3–1.5). Multivariate adjustment for tumor size and histologic tumor necrosis attenuated the association among all patients (HR, 1.3; 95% CI, 0.8–2.1) but strengthened the association among patients with high‐grade tumors (HR, 2.7; 95% CI, 1.3–5.6).
CONCLUSIONS
The current data suggest that IGF‐IR expression is associated with poor survival in patients who are diagnosed with early‐stage CC‐RCC, especially among those with high‐grade disease. Cancer 2004. © 2004 American Cancer Society.