BACKGROUND: The ongoing approval of adjuvant systemic therapy in high-risk kidney tumor will increase the demand for prognostic assessment in these tumors. 9p21 deletion has been suggested as a possible prognostic feature in clear cell kidney cancer.
MATERIAL AND METHODS: To learn more on the prognostic relevance of 9p21 deletions in clear cell and other kidney tumors, 1,809 kidney tumor specimens were analyzed by dual-labeling fluorescence in situ hybridization (FISH) with probes for 9p21 and centromere 9 in a tissue microarray format. Results were compared to histologic tumor type, pT stage, grade, and patient outcome.
RESULTS: A total of 1,341 (74%) of tumor samples had interpretable FISH results. 9p21 deletion was found in 4.4% of 894 clear cell, 5.1% of 197 papillary, and 4.2% of 71 chromophobe carcinomas. 9p21 deletions were not found in 112 oncocytomas and in 21 clear cell tubulo-papillary cancers. In clear cell carcinomas, 9p deletions were associated with advanced stage (P = 0.009) and nodal metastasis (P = 0.0067), but not with ISUP grade (P = 0.1039) and distant metastasis (P = 0.4809). Also, in papillary carcinomas, 9p deletions were associated with advanced stage (P = 0.0008) and nodal metastasis (P = 0.0202) but not with ISUP grade (0.0904) and distant metastasis (P = 0.2022). Follow-up data were available for 789 clear cell and 177 papillary cancers. In both tumor entities, 9p21 deletions were associated with shortened overall survival, tumor-specific death, and progression-free survival in univariate analysis (P < 0.02 each). In a multivariate analysis, 9p21 deletion was an independent predictor of early tumor recurrence (P = 0.04).
CONCLUSION: 9p21 deletions, 9p21 deletions identify a small subset of aggressive renal carcinomas. 9p deletion assessment may be clinically useful to identify high-risk renal cell carcinomas.