UroToday - Accurate prediction of outcome after hormonal treatment for localized prostate cancer is important for patient counselling, follow-up, treatment planning and research protocol design. Few prognostic tools incorporating pre-therapeutic parameters are available to increase disease relapse predictions and survival. Many studies have highlighted the correlation between the importance of PSA decrease following androgen deprivation therapy (ADT) - mainly nadir PSA - and survival time. This important prognostic information lacks obviously at the onset of ADT.

This is what makes the percentage of positive biopsy cores of such interest. Taking into account the pre-therapeutic, readily available, potential predictors of prostate cancer, we found that the percentage of positive biopsy cores was a significant predictor of time to castrate resistant prostate cancer, as well as specific and overall survivals. Multivariate analyses showed that it was an independent predictor of survival when considering the whole study group, although the percentage of positive biopsy cores was significantly associated with Gleason score and PSA level at diagnosis.

Several studies found that this percentage was an independent predictor of all pathologic or biochemical outcomes following radical prostatectomy, external beam radiotherapy and brachytherapy. However, these treatments are indicated when prostate cancer is considered as localized. As the percentage of positive biopsy cores can be considered as a surrogate for tumour volume and stage, the association between percentage of positive biopsy cores and outcome could be expected. This is not the case for non-localized prostate cancer, which makes our results less obvious to explain. Only 6% of the patients included in our study had a low to intermediate risk localized prostate cancer and yet the percentage of positive biopsy cores was as an independent factor of progression and survival. We have then to admit that the volume of the prostatic tumour has an independent prognostic effect even if the tumour is already disseminated. Interaction between the primary tumor and its metastasis is complex and goes beyond simple cell seeding. Distant tumor cells respond to an array of growth factors produced by the primary tumor. In many cancers, such as ovarian and breast cancers, removal of the primary tumor improves overall survival in metastatic patients. Thus, indirectly, our findings raise a poorly investigated issue in urology: the role of primary tumor treatment in metastatic prostate cancer.

Our findings have some limits, the most obvious being its retrospective characteristic. It spanned a period of nearly 2 decades. Also, the total number of cores that we obtained ranged from 2 to 7 with a median of 6. Currently, the standard number of extracted cores is between 8 and 12. Still our study of 403 patients with an overall mean follow-up of 5 years supports the concept of a significant association between the proportion of positive biopsy cores and the prognosis of prostate cancer treated by hormonal therapy. To our knowledge, this was brought up for the first time by this study and warrants further investigations to be validated and refined, using contemporary biopsy schemes.

Jacques Irani, MD as part of Beyond the Abstract on UroToday.

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