ASCO GU 2020: Prognostic Factors that Affect Survival Outcomes in Men with Metastatic Castration-Resistant Prostate Cancer Treated with Radium-223

San Francisco, CA ( Radium-223 is a targeted alpha therapy. it is incorporated into areas of the bone where there is increased osteoblastic activity and increased bone turnover from skeletal metastasis. Bone metastases occur in approximately 90% of men with metastatic castrate-resistant prostate cancer and can cause significant morbidity. This can be in the form of pain, pathological fractures, spinal cord compression and bone marrow failure.

Radium-223 has been shown in a randomized Phase III study to cause a significant improvement in overall survival and symptomatic skeletal-related events. Furthermore, more than 30% reduction in PSA blood levels at week twelve was achieved in 16% of patients treated with radium-223.

To date, there are no clear clinicopathological prognostic factors that may guide the selection of radium-223 for mCRPC patients.

The primary objective of this study was to analyze the survival outcomes and progression-free survival of men with metastatic castration-resistant prostate cancer who were treated with radium-223 with longer follow up in the Princess Margaret Cancer Centre. The secondary objective was to determine the prognostic factors that may affect the overall survival and to define the optimum number of radium-223 cycles that can affect the survival outcomes.

This retrospective study included 114 patients treated between 2015 and 2018. Table 1 shows patient demographics and table 2 demonstrates the patient demographics of those receiving more than four cycles compared to those receiving 4 cycles or less. 

Table 1. Patient/treatment demographics (N=114)

patient treatment demographics

Table 2. Patient/treatment demographics for those received ≤ four cycles versus > four cycles

patient demogrpahics for more than 4 cycles

Figure 2 demonstrates the multivariable analysis of patient characteristics trying to predict overall survival. Figures 3 and 4 demonstrate Kaplan Meier curves for progression-free survival and overall survival, respectively, for patients who received one to four cycles versus five to six cycles of radium-223.

Multivariate analysis of patient characteristics

Figure 2
. Multivariate analysis of patient characteristics

kaplan meier curve of PFS

Figure 3. Kaplan Meier curve of progression-free survival for patients received 1-4 versus 5-6 cycles of radium-223

kaplan meier curve of OS

Figure 4. Kaplan Meier curve of overall survival for patients receiving 1-4 versus 5-6 cyclea of radium-223

The authors concluded that the median overall survival for all patients treated with radium-223 in this center was 12 months. Multivariable analysis demonstrated that baseline ALP less than 150 U/L, baseline PSA less than 70 ug/L and treatment administration of more than four cycles of radium-223 were all associated with improved overall survival. The authors suggest using these parameters to identify patients most likely to benefit from this type of treatment.

Presented by: Esmail Al-Ezzi, MBBS, University Health Network, Toronto, Canada

Written by: Hanan Goldberg, MD, Urology Department, SUNY Upstate Medical University, Syracuse, New York, Twitter: @GoldbergHanan at the 2020 Genitourinary Cancers Symposium, ASCO GU #GU20, February 13-15, 2020, San Francisco, California