Association between PSA values and surveillance quality after prostate cancer surgery

Bayesian Spatio-Temporal Multilevel Modelling of Patient-Reported Quality of Life following Prostate Cancer Surgery

BACKGROUND

Globally, prostate cancer is the second leading cause of cancer deaths among males. It is the most commonly diagnosed cancer in Australia. The quality of life of prostate cancer patients is poorer when compared to the general population due to the disease itself and its related complications. However, there is limited research on the geographic pattern of quality of life and its risk factors in Victoria. Therefore, an examination of the spatio-temporal pattern and risk factors of poor quality of life, along with the impact of spatial weight matrices on estimates and model performance, was conducted.

METHOD

A retrospective study was undertaken based on the Prostate Cancer Outcome Registry-Victoria data. Patient data (n = 5238) were extracted from the Prostate Cancer Outcome Registry, a population-based clinical quality outcome assessment from 2015 to 2021. A Bayesian spatio-temporal multilevel model was fitted to identify risk factors for poor quality of life. This study also evaluated the impact of distance- and adjacency-based spatial weight matrices. Model convergence was assessed using Gelman-Rubin statistical plots, and model comparison was based on the Watanabe-Akaike Information Criterion.

RESULTS

A total of 1906 (36.38%) prostate cancer patients who had undergone surgery experienced poor quality of life in our study. Belonging to the age group between 76 and 85 years (adjusted odds ratio (AOR) = 2.90, 95% credible interval (CrI): 1.39, 2.08), having a prostate-specific antigen level between 10.1 and 20.0 (AOR = 1.33, 95% CrI: 1.12, 1.58), and being treated in a public hospital (AOR = 1.35, 95% CrI: 1.17, 1.53) were significantly associated with higher odds of poor quality of life. Conversely, residing in highly accessible areas (AOR = 0.60, 95% CrI: 0.38, 0.94) was significantly associated with lower odds of poor prostate-specific antigen levels. Variations in estimates and model performance were observed depending on the choice of spatial weight matrices.

CONCLUSION

Belonging to an older age group, having a high prostate-specific antigen level, receiving treatment in public hospitals, and remoteness were statistically significant factors linked to poor quality of life. Substantial spatio-temporal variations in poor quality of life were observed in Victoria across local government areas. The distance-based weight matrix performed better than the adjacency-based matrix. This research finding highlights the need to reduce geographical disparities in quality of life. The statistical methods developed in this study may also be useful to apply to other population-based clinical registry settings.

A Refinement of Clinical Tumor Marker Monitoring: Why Not Use an Inverse Value of Doubling Time?

OBJECTIVES

The aim of this study was to compare prostate-specific antigen (PSA) kinetics - half-life time (HT), doubling time (DT), and elimination rate PSA (ePSA) in prostate cancer (PCa) monitoring. Implementation of ePSA in clinical practice could help simplify patient monitoring in the remission phase.

MATERIALS AND METHODS

A total of 49 PCa patients were examined by their PSA tests before prostatectomy and after 30 days, 91 days, and 24 months. Conventional PSA rate of change parameters (HT and DT) were compared to a new clinically understandable ePSA parameter.

RESULTS

We observed that implementation of inverse value (ePSA) rather than HT or DT has distinct advantages: (1) values are valid when PSA is unchanged (ePSA equals zero), (2) the concept of ePSA can be easily understood, as it is a growth fraction, (3) ePSA fluctuates within a narrow range and is thus easy to interpret, and (4) there are no mathematical flaws (no positive skewing).

CONCLUSION

Exploring ePSA norm as ≤0% could help spot biochemical recurrence in a timely manner. Primary health care providers tend to use an irrelevant PSA threshold, that is, 4.0 ng/mL, in postoperative follow-up. The delayed referrals of patients in remission might be reduced if ePSA testing is adopted.

Association between PSA values and surveillance quality after prostate cancer surgery

BACKGROUND

Although prostate-specific antigen (PSA) testing is used for prostate cancer detection and posttreatment surveillance, thresholds in these settings differ. The screening cutoff of 4.0 ng/mL may be inappropriately used during postsurgery surveillance, where 0.2 ng/mL is typically used, creating missed opportunities for effective salvage radiation treatment. We performed a study to determine whether guideline concordance with annual postoperative PSA surveillance increases when PSA values exceed 4 ng/mL, which represents a screening threshold that is not relevant after surgery.

METHODS

We used US Veterans Health Administration data to perform a retrospective longitudinal cohort study of men diagnosed with nonmetastatic prostate cancer from 2005 to 2008 who underwent radical prostatectomy. We used logistic regression to examine the association between postoperative PSA levels and receipt of an annual PSA test.

RESULTS

Among 10 400 men and 38 901 person-years of follow-up, annual guideline concordance decreased from 95% in year 1 to 79% in year 7. After adjustment, guideline concordance was lower for the youngest and oldest men, Black, and unmarried men. Guideline concordance significantly increased as PSA exceeded 4 ng/mL (adjusted odds ratio 2.20 PSA > 4-6 ng/mL vs PSA > 1-4 ng/mL, 95% confidence interval 1.20-4.03; P = .01).

CONCLUSIONS

Guideline concordance with prostate cancer surveillance increased when PSA values exceeded 4 ng/mL, suggesting a screening threshold not relevant after prostate cancer surgery, where 0.2 ng/mL is considered treatment failure, is impacting cancer surveillance quality. Clarification of PSA thresholds for early detection vs cancer surveillance, as well as emphasizing adherence for younger and Black men, appears warranted.