) Assessing prognosis of tumor growth potential in biopsy material is vital to choosing an appropriate therapy in prostate cancer. However, definitive molecular markers on which to base a prognosis are limited. Telomere DNA, the tandem six-base nucleotide repeats that cap and protect chromosome ends, are typically shorter in cancer cells. This suggests that telomere length may be an important determinant of tumor progression. A new slot blot assay which measures Telomere DNA Content (a proxy for telomere length) was developed by the Principal Investigator using tumor tissue. Results of this assay indicate that reduced telomere DNA content in breast cancer is correlated with aneuploidy (p less than 0.002) and metastasis (p less than 0.05) and in prostate cancer with reduced survival (p less than 0.004) and increased disease recurrence (p less than 0.0001). In Phase I, we will extend and refine the telomere DNA content assay to accommodate prostate needle-core biopsy specimens. In Phase II, we will utilize the assay to conduct a retrospective case-control study of archival prostate needle-core biopsies. The telomere DNA content data will be correlated to patient survival and the results evaluated to ascertain the predictive value of telomere DNA content in prostate biopsy samples.