Importance of PSA Kinetics as a Prognostic Factor in Locally Advanced/Metastatic Prostate Cancer Patients with Prior Androgen Deprivation Therapy

Abstract Background Prostatic cancer ranks 2nd amongst men in worldwide while 4th in Egypt. Many factors are used to predict patients’ survival. PSA kinetics are one of the main prognostic factors used for treatment response in advanced or relapsed cases. However, its application as prognostic marker is lacking in Egyptian clinical settings and research. Aim of Study In this retrospective study, we aimed to assess correlation between PSA kinetics among locally advanced and metastatic prostatic cancer patients and their survival status for prognostic aspects. Methods We conducted a retrospective cohort study at Clinical Oncology department, Ain Shams University hospitals from January 2013 till December 2022 (10 years). All prostate cancer patients who were initially hormonal sensitive locally advanced or metastatic that later developed biochemical failure during follow up period were included in our study. Results Our study included 77 patients with a mean age of 66.4±7.4 years. Three cases were locally advanced while 74 cases were metastatic. The most frequent mode of ADT monotherapy prior biochemical failure was GnRH analogue in 55 cases. Upon disease progression, most of the cases were shifted to abiraterone acetate. The initial median PSA value was 100 (49.1-193.9) ng/ml. It took about 9 (6-14) months (median TTN) with a median declining rate of 10.5 (3.75-35.1) % for their PSA values to reach nadir level of median 1.2 (0.21-5.27) ng/dl. When ADT failed, PSA levels increased again reaching a median value of 8.9 (3.75-35.2) ng/ml. The median PSA velocity after progression was 35.2 (2.8-208) ng/dl/yr while median PSA DT was 3.6 (1.3-7.25) months. Univariate analysis revealed PSA nadir <0.76 ng/dl level (P value= 0.003) and TTN >11 m (p value = 0) significantly associated with longer PFS and improved survival. However, PSA DT < 3.1 (p value=0.017) predicts higher mortality. Meanwhile, multivariate results showed that PSA declining rate (P value= 0.047) and age > 67 years (P value 0.016) were statistically significant as independent factors when associated to PFS. Conclusion TTN > 11 months and PSA nadir <0.76 during initial treatment was associated with prolonged PFS and OS. They were associated with better clinical response to treatment in castration resistant prostate cancer patients. Thus, it could be helpful for decision making of early treatment strategy in castration resistant cases.