Factors associated with response to Androgen Deprivation Therapy in patients with Metastatic Prostate Cancer at the University Teaching Hospital Lusaka, Zambia

Abstract

Background: Prostate cancer in most cases is dependent on the presence of androgens (testosterone) produced either by the testis or adrenal gland. The major risk factors for development include aging, ethnicity and genetic predisposition. Organ confined prostate cancer is curable by surgery or radiotherapy while metastatic disease is treated by androgen deprivation therapy (ADT). ADT can be achieved medically (gonadotropin releasing hormone agonists or antagonists) or surgically (bilateral orchiectomy).  A decrease in serum prostate specific antigen (PSA) is used as a marker of response to ADT. Metastatic prostate cancer has been found to be the most common cause of death in the urology department at the University Teaching Hospitals – Adult Hospital even after ADT, therefore, the aim of this study was to identify the pre-treatment factors that can be used to determine the response to ADT.

Methodology: This was a cross section study conducted at the University Teaching Hospitals- Adult Hospital and Cancer Diseases Hospital. It was carried out between December 2017 and September 2018. Patients with metastatic prostate cancer were recruited. Socio-demographic characteristics, clinical presentation and histopathological findings were elicited by detailed history and file review. PSA and Eastern Cooperative Oncology Group (ECOG) performance status score were obtained prior to ADT commencement. ADT was done and patients were scheduled for a three month post ADT review where PSA and ECOG performance status score were reobtained.

Results: 50 patients were recruited into the study. The total patient retention was 88% (n=44). The average age was 71. Majority, 89% (n=39) had some level of education; 98% (n=43) had lower urinary tract symptoms (LUTS); 11% (n=5) had paraplegia. 98% (n=43) had bone metastasis. Duration of symptoms at presentation was > 6 months in 75% (n=33) patients. ECOG score was above 1 in 75% (n=33). Initial PSA was above 100ng/ml in 75% (n=38). All patients had Gleason scores above 7. All patients had a drop in PSA after ADT. The average PSA percentage drop in men below 60 years was 80.5% whereas the average percentage drop in PSA with regards to other factors was 91.19%.

Conclusion: All patients had androgen dependant cancers. These patients also had high risk prostate cancer with initial PSA values above 100ng/ml and Gleason scores above 7. Of all the factors analysed, age below 60 years was found to be the only clinically significant factor associated with poor response to ADT.