Objective:

To determine if the time to achieve a PSA nadir is related to a delay in the progression of the disease.

Material and methods:

A retrospective study of 36 patients treated with abiraterone acetate in our facilities between January 2014 and May 2018 in CPRC M1 phase. PSA levels are evaluated at the beginning of the treatment, after 4, 8 and 12 weeks, as well as in the successive periods according to our protocol. PSA response is defined as a decrease of ≥30% from the start of treatment and PSA progression as an increase of ≥25% from the beginning. It is considered as 'progression that supposes withdrawal of treatment' the one that associates at least two of the following criteria: PSA progression, clinical progression and radiological progression. We performed a linear regression analysis for PSA variables at diagnosis, PSA nadir, time at nadir, PSA doubling time and decrease of at least 30% of the nadir.

Results:

In our series, time to nadir in linear regression is positively associated with progression, obtaining better progression-free survival when a longer-term nadir PSA is achieved (p <0.018); so that for every month of delay in reaching the nadir, a 0.8 months belated progression is expected.

Conclusion:

In our series, achieving a belated PSA nadir is related to an improvement in progression-free survival.

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