Abstract 354P
Background
Mixed subtype adenocarcinoma of the prostate is a rare and aggressive form of prostate neoplasm. Despite its clinical significance, it remains underexplored, with limited available data. This study aimed to investigate its clinicopathological features and survival outcomes to provide updated evidence to the literature about the nature of this rare type.
Methods
We extracted data for 397 patients with mixed subtype prostate adenocarcinoma from the SEER database (2000–2021). Patients were subgrouped by treatment: surgery with systemic therapy, surgery without systemic therapy, and primary systemic therapy. Overall survival (OS) and cancer-specific survival (CSS) were calculated using survival analysis with Kaplan-Meier curves and Log-Rank tests. Cox regression identified predictors of OS.
Results
The median age for mixed subtype prostate adenocarcinoma was 66 years (IQR= 61-73). The overall age-adjusted incidence rate was 0.218 per 1,000,000 population. The 3-year and 5-year OS were 80.8% and 75.9%, while CSS at these intervals were 86.7% and 84.5%. The group treated surgically without systemic therapy had better 5-year survival compared to those who received surgery with systemic therapy and primary systemic therapy (93.8%, 80.3%, and 71.6%, respectively; P < 0.001). Cox regression identified primary systemic therapy, age, and marital status as independent survival factors. Primary systemic therapy doubled the risk of death compared to surgery with no systemic therapy (HR = 1.954, 95%; P = 0.008). Adjuvant therapy had no association with survival (HR = 1.34; P = 0.27). Patients aged 65+ had a higher risk of death (HR = 1.972; P = 0.002), while married individuals had a 53.5% lower risk than unmarried counterparts (HR = 0.535; P = 0.004). PSA level, race, residence status, year of diagnosis, and tumor grade were not associated with survival.
Conclusions
Prostate adenocarcinoma with mixed subtypes has a good overall survival outcome. Surgery without systemic therapy is the optimal treatment modality, offering significant survival benefits and avoiding the complications of systemic therapy. These findings are vital for developing tailored treatment plans for this rare and aggressive tumor subtype.
Clinical trial identification
Editorial acknowledgement
Legal entity responsible for the study
The authors.
Funding
Has not received any funding.
Disclosure
All authors have declared no conflicts of interest.