This study examined tumor volume, tumor percentage and number of tumor foci as predictors of prognosis in prostate cancer.

Multiple variables are often used to predict prognosis among prostate cancer patients. These including PSA levels (prostate specific antigen; a protein produced by prostate cells whose levels rise with growing prostate cancer), Gleason score (a scale of cancer aggressiveness based on the microscopic appearance of the cancer cells) and tumor stage (determined by the extent of tumor growth and spread).

However, the prostate cancer tumor staging system does not always reflect the actual size of the tumor. Researchers therefore hypothesized that tumor volume and tumor percentage (the percentage of the prostate gland filled by the tumor) may present as more accurate predictors of prognosis. The number of tumor foci (the number of growing tumors present in the prostate gland) was also assessed as a third possible predictor of prognosis.

This study included 758 localized prostate cancer patients treated by radical prostatectomy (surgical removal of the prostate). Prior to surgery, PSA, Gleason score, tumor stage, tumor volume, tumor percentage and the number of cancer foci were recorded. Patients were followed for an average of 62 months following surgery. PSA levels were measured every six months as surveillance for possible recurrence (referred to as biochemical recurrence).

598 men were designated as high-risk for recurrence, based on higher PSA levels, Gleason scores and tumor staging. 22.9% of these patients experienced a rise in PSA levels during follow-up. Of the 160 men considered low-risk, 9.9% experienced biochemical recurrence during follow-up. Among high-risk patients, tumor percentage was found to be an independent predictor of biochemical recurrence. Patients with a tumor percentage of greater than 20% were 1.5 times more likely to experience biochemical recurrence than patients with lower tumor percentages. Among low-risk patients tumor percentage was not predictive of biochemical recurrence. Neither tumor volume, nor the number of tumor foci were found to be reliable predictors of prognosis.

This study concluded that tumor percentage is an independent predictor of prognosis among high-risk prostate cancer patients.