Sitnikova L et al. (2008) IMP3 predicts aggressive superficial urothelial carcinoma of the bladder. Clin Cancer Res 14: 1701–1706

Predicting the risk of tumor progression in superficial urothelial carcinoma is currently difficult. Sitnikova et al. have examined the utility of using IMP3—an oncofetal protein—as a biomarker to distinguish between tumors with a high probability of progression and those that are unlikely to become invasive.

The researchers examined the expression of IMP3 in 214 patients with superficial urothelial carcinoma. IMP3 expression was noted in 20% of primary superficial urothelial carcinomas and in 93% of metastatic urothelial carcinomas. IMP3 expression was significantly associated with disease recurrence (P = 0.029), tumor stage (P = 0.016) and tumor grade (P <0.0001). Progression-free and disease-free survival times were significantly longer in patients with non-IMP3-expressing carcinomas than in patients with carcinomas expressing this protein (P = 0.0002 and P = 0.0067, respectively). The 5-year progression-free and disease-free survival rates for IMP3-negative patients were 91% and 94%, compared with 64% and 76% for IMP3-positive patients. Multivariate analyses adjusted for age, tumor size, tumor stage and grade, multiplicity and treatment with bacillus Calmette-Guérin revealed IMP3 expression to be a strong independent predictor of clinical outcome. The hazard ratio for progression-free survival in IMP3-positive versus IMP3-negative patients was 6.46 (95% CI 2.19–19.05; P = 0.001), and the hazard ratio for disease-free survival was 2.82 (95% CI 1.18–6.71; P = 0.019).

The authors conclude that IMP3 expression has prognostic value in superficial urothelial carcinoma and could be used to identify those patients who are likely to show progression and who would, therefore, benefit from aggressive treatment.