A low prostate-specific antigen (PSA) value continues to be a helpful prognostic marker in the setting of hormone-sensitive metastatic prostate cancer, even as standard treatment evolves.
The finding comes from a retrospective analysis published online December 20, 2017, in the Journal of Clinical Oncology.
Among oncologists and urologists, it is well known that a PSA level of 0.2 ng/mL or less in these men at 7 months after the initiation of androgen deprivation therapy (ADT) portends a significantly longer survival than seen in men with PSA values above this cutoff point.
But that insight comes from a study published more than 10 years ago, the Southwest Oncology Group 9346 trial (J Clin Oncol. 2006;24:3984-3990).
At that time, ADT alone was the mainstay of treatment. But times and treatments change.
Now, thanks to findings from the more recent CHAARTED and STAMPEDE trials, many of these patients receive chemotherapy with docetaxel in addition to ADT, especially if they have high-volume metastatic disease. Both of these major trials showed significantly improved overall survival when chemotherapy was added to androgen blockade in advanced prostate cancer.
But it has not been known, in the current treatment era, whether the PSA biomarker remained prognostic when docetaxel was added to ADT.
So the CHAARTED investigators performed a retrospective "landmark survival analysis" at 7 months using the database from their trial.
They conclude that "PSA ≤ 0.2 ng/dL at 7 months is prognostic for longer overall survival with ADT for metastatic hormone-sensitive prostate cancer irrespective of docetaxel administration."
Finding Provides Optimism and Guidance
For clinicians, the new findings provide both "optimism at the bedside and perhaps also guidance on how close to follow patients," said investigators Lauren Harshman, MD, and Christopher Sweeney, MD, from the Dana-Farber Cancer Institute in Boston, Massachusetts, in an email to Medscape Medical News.
The suggestion here is that for clinicians working with men whose PSA levels are below the cutpoint, there is positive news to share, while for men with PSA levels above that cutoff point, there is possible guidance for closer monitoring.
Study Details
In the study, 719 of the original 790 patients were eligible for the new subanalysis; 358 were treated with ADT plus docetaxel and 361 with ADT alone. The team used the three prognostic classifiers identified from the earlier SWOG 9346 trial: PSA level of 0.2 ng/dL or less, greater than 0.2 to 4 ng/dL, and greater than 4 ng/dL.
The median follow-up was 23.1 months.
Across all patients, median overall survival was significantly longer if the 7-month PSA level reached 0.2 ng/dL or less vs survival seen with levels greater than 4 ng/dL (median survival, 60.4 months vs 22.2 months, respectively; P < .001).
The paragraph that strikes me is:
"They conclude that "PSA ≤ 0.2 ng/dL at 7 months is prognostic for longer overall survival with ADT for metastatic hormone-sensitive prostate cancer irrespective of docetaxel administration."
Of course what do I know?