A139: Radiotherapy and the risk of thromboembolic disease in men with prostate cancer
1King’s College London, London, UK,2Umea University, Umea, Sweden,3Skåne University, Malmö, Sweden,4Karolinska Institutet, Stockholm, Sweden
Using data from PCBaSe Sweden, we have previously shown that the risk of deep venous thrombosis (DVT) and pulmonary embolism (PE) is increased among men with prostate cancer (PCa), especially those who undergo surgery or are treated with androgen deprivation therapy. Interestingly, several case reports and experimental studies have now also suggested an association between radiotherapy (RT) and risk of thromboembolic disease (TED). The current study therefore investigates in detail the risk of TED following RT in a large cohort of men with PCa.
Apart from data on tumour characteristics and primary treatment for men with PCa, PCBaSe Sweden also contains a retrospectively collected RT database (RetroRad) with information on e.g. treatment technique and delivered dose. We identified all men who received RT as curative treatment (n=71,352) and grouped them into external beam RT (EBRT) or brachytherapy (BT). By comparing with an age and county-matched comparison cohort of PCa-free men (n=300,679), we investigated risk of TED following RT using Cox proportional hazard regression. The model was adjusted for tumour characteristics, demographics, comorbidities, PCa treatments, and known risk factors of TED such as recent surgery and disease progression
Between 2006 and 2013, 67,398 men with PCa received EBRT and 3,954 underwent BT. A statistically significant association was found between EBRT and risk of PE in the crude analysis HR: 1.65 (95%CI: 1.30-2.10). However, upon adjusting this association disappeared. A more detailed analysis investigating risk of TED by time since RT showed a decreasing trend over time for PE (HR: 1.93 (95%CI: 1.28-2.91) and 1.57 (95%CI: 1.20-2.06) at <1y and ?1y, respectively). However, upon adjusting for potential confounders, this association also disappeared.
In this large representative cohort of men with PCa, we did not find an increased risk of TED following RT with curative intent.