Session Item

Stereotactic body radiotherapy (SBRT) is emerging as a low-toxicity treatment for prostate cancer (PCa) localizations allowing to postpone androgen deprivation therapy (ADT) in oligometastatic setting. In the phase II randomized clinical trial RADIOSA (NCT03940235, estimated primary completion date April 2022) the biology task comprises the identification of predictive and prognostic biomarkers in the setting of oligorecurrent-castration-sensitive PCa in order to discriminate poly- from oligo-metastatic patients, who could benefit from metastases-directed-therapies. This preliminary subgroup analysis aims to evaluate the change at 3 months of serum derived biomarkers after SBRT +/- ADT.

Patients matching the inclusion criteria of the study were stratified in two treatment groups according to ADT administration and site of metastases. The present analysis comprises all the enrolled patients with a minimum follow-up of 3 months. Common serum-derived biomarkers (albumine, total cholesterol, neutrophil and lymphocyte count) were collected at baseline and 3 months after RT. Controlling nutritional status (CONUT) score, a scoring system used to assess patient nutritional status, and prognostic nutritional index (PNI), an immunity and nutrition based prognostic score, were calculated according to available literature. Neutrophil-lymphocyte ratio (NLR) and NLR-albumine ratio (NLRAR) were evaluated as inflammatory status scores.  Significant changes in collected samples were evaluated for ADT administration (yes vs no) and site of metastases (bone vs lymph node) with univariate non parametric Wilcoxon signed-rank test.

Fifty-four patients were included in the following preliminary analysis. When stratified by ADT administration, statistically significant differences in PNI were observed in favor of the ADT-free group (p= .046). As expected, differences in the total cholesterol count showed an increasing trend in the group receiving ADT (p= .003). When patients were stratified by site of metastases, inflammatory scores (NLR and NLRAR) showed a higher inflammatory status in patients with bone localizations (p = .006 and p= .030 respectively). It is well-known that higher inflammatory status is associated with a worse prognosis such as bone localization is slightly worse in terms of response compared to lymph nodes only sites.

Nutritional status appears to be affected by ADT addition, a well-known factor for quality of life worsening. Moreover, inflammatory status seems to be related with site of metastatic localization. Analyzed parameters would appear to represent interesting candidate to be possibly included in clinical decision-making in order to stratify patients who would benefit from more or less aggressive treatments. Further evaluations and correlations with clinical outcomes and longer follow-up are needed for the validation of these candidate biomarkers.