Androgen deprivation therapy for prostate cancer and the risk of hospitalisation for community-acquired pneumonia.

BACKGROUND:
Androgens have been shown to influence both the immune system and lung tissue, raising the hypothesis that androgen deprivation therapy (ADT) for prostate cancer may increase the risk of pneumonia. Thus, the aim of this study was to determine whether ADT is associated with an increased risk of hospitalisation for community-acquired pneumonia in patients with prostate cancer.

METHODS:
This was a population-based cohort study using the United Kingdom Clinical Practice Research Datalink linked to the Hospital Episode Statistics repository. The cohort consisted of 20 310 men newly diagnosed with non-metastatic prostate cancer between 1 April 1998 and 31 March 2015. Time-dependent Cox proportional hazards models were used to estimate adjusted HRs and 95% CIs for hospitalisation for community-acquired pneumonia associated with current and past use of ADT compared with non-use.

RESULTS:
During a mean follow-up of 4.3 years, there were 621 incident hospitalisations for community-acquired pneumonia (incidence rate: 7.2/1000 person-years). Current ADT use was associated with an 81% increased risk of hospitalisation for community-acquired pneumonia (12.1 vs 3.8 per 1000 person-years, respectively; HR 1.81, 95% CI 1.47 to 2.23). The association was observed within the first six months of use (HR 1.73, 95% CI 1.23 to 2.42) and remained elevated with increasing durations of use (≥25 months; HR 1.79, 95% CI 1.39 to 2.30). In contrast, past ADT use was not associated with an increased risk (HR 1.23, 95% CI 0.95 to 1.60).

CONCLUSIONS:
The use of ADT is associated with an increased risk of hospitalisation for community-acquired pneumonia in men with prostate cancer.