INTRODUCTION
Abiraterone acetate (AA) has demonstrated increased overall survival in patients with metastatic castration-resistant prostate cancer (mCRPC). The appearance of AA in 2012 was a revolution. AA offered a more therapeutic alternative to chemotherapy. In addition, AA was especially relevant in patients unfit for chemotherapy because it was possible to offer them a treatment with impact on the overall survival.
MATERIAL AND METHODS
We performed a retrospective review of chemotherapy-naïve mCRPC patients treated with AA in our center. Patients were divided in two groups: patients who started treatment in the period 2012-2014 and others who began treatment in 2015-2016.
The objective was to demonstrate that the early detection of the metastasis in CRCP and the early initiation of treatment with a smaller metastatic volume had an impact on overall survival and clinically-radiographic progression-free survival.
RESULTS
A total of 28 patients chemotherapy-naïve mCRPC received AA between 2012 and 2016. Of these, 11 patients started treatment in the period 2012-2014 and 17 between 2015-2016. The mean follow-up was 12.65 months. 13 patients remain alive (9 continue treatment with AA), 10 died due to prostate cancer and 5 for other causes.
The median overall survival was higher in the 2015-2016 group (13.81 months vs. not yet reached, p = 0.037). The median of clinically-radiographic progression-free survival was higher in the 2015-2016 group (5.19 vs. 12.64 months, p = 0.064), although statistical significance was not reached.
Although the population of 2015-2016 was younger (mean age 84.27 vs. 77.88 years, p=0.044), this period had more patients diagnosed with initial mCPRC (22.2 vs. 66.6%, p=0.035) . Morover, patients from 2012-2014 presented higher tumor volume expressed in median PSA at the beginning of AA (74.3 vs. 14.5 ng/ml, p=0.007) and a higher percentage of patients with ≥10 bone metastases (72.7 vs. 31.3%, p=0.034).
Patients in the group of 2015-2016 had a greater proportion of Gleason ≥8 (44.4 vs. 80 %; p=0.074) despite statistical significance was not reached. We found no differences in relation to ECOG ≥1 (45.5 vs. 47.9%, p=0.934) or BPI≥1 (30 vs. 29.4%, p=0.974).
The median time from diagnosis of mRCPC to the beginning of AA was higher in the period 2012-2014 (3.5 vs. 0 months, p = 0.006).
CONCLUSION
In our series, patients treated in the 2015-2016 period had a greater median survival than in the period 2012-2014. This benefit in survival could be explained because it was a younger population and with a smaller metastatic tumor volume (assessed in relation to PSA and the proportion of patients with ≥ 10 bone metastases). Additionally, in the period 2012-2014, a group of elderly patients who were not receiving chemotherapy were rescued with AA(represented at time from mRCPC to the beginning of AA).
If we evaluate the impact of the response to AA as a function of the median of clinically-radiographic progression-free survival and thus excluding the effect of age, the 2015-2016 period has a tendency towards a longer response.
In our series, we conclude that the fact of starting treatment early and, therefore, with a lower tumor volume has an impact on survival. These results should be evaluated taking into account the low population of the sample and the fact that it is a retrospective review.
