Prostate Cancer Could Increase Risk of DVT, Pulmonary Embolism by Nearly 50%

Men with prostate cancer were at a 50% greater risk of developing venous thromboembolism (VTE) in the first 5 years after their cancer diagnosis compared to men without prostate cancer, according to recent study in Sweden.

An analysis of data from a population-based cohort study of more than 550,000 men in Sweden, results of the study demonstrate those with prostate cancer were at a 48% greater risk of deep vein thrombosis and a 47% greater risk of pulmonary embolism after adjustment for patient characteristics.

“The magnitude of increased VTE risk among men with prostate cancer seen in our study is lower than that seen for other cancer types as seen in previous studies and is likely attributable to the high proportion of men with localized disease and at low risk of cancer progression,” wrote investigators. “Notwithstanding this, physicians treating men with prostate cancer should be aware of the marked increase in VTE risk in these men, particularly in the first six months following cancer diagnosis, to help ensure timely VTE diagnosis.”

With funding from Bayer AG, the current study was launched by investigators at the School of Cancer and Pharmaceutical Sciences at Uppsala University in Sweden and Bayer AG with the intent of assessing the risk of VTE among those with prostate cancer using data from the Nationwide Prostate Cancer data Base Sweden (PCBaSe). From PCBaSe, investigators identified 92,105 men with a first diagnosis of prostate cancer from 2007-2016 who were matched in a 5:1 ratio by birth year and residential region to 466,241 men without prostate cancer for inclusion in their analyses. Of note, men with T stage 0 or X and those with a previous record VTE were excluded from the study.

The primary outcome of interest for the investigators’ analyses were crude incidence proportion ratios (IPRs) for incidence of VTE in men with prostate cancer compared to men in the control cohort. Investigators pointed out Cox regression was used to calculate the hazard ratios for VTE, with adjustment for confounding factors, which included comorbidities, medication use, and sociodemographic factors.

Among the entire study cohort, 2955 men with prostate cancer and 9774 men without prostate cancer experienced a first VTE event during a median of 4.5 years of follow-up, with deep vein thrombosis accounting for 52% of the total VTE cases. Further analysis indicated the median time from start of follow-up to VTE was 2.5 (IQR, 0.9-4.7) years in the prostate cancer cohort and 2.9 (IQR, 1.3-5.0) years in the control cohort.

When assessing incidence rates, results demonstrate the crude incidence rates of VTE per 1000 person-years was 6.54 (95% CI, 6.31-6.78) in the prostate cancer cohort and 4.27 (95% CI, 4.18-4.35) in the comparison cohort. Further analysis indicated IPRs decreased from 2.53 (95% CI, 2.26-2.83) at 6 months to 1.59 (95% CI, 1.52-1.67) at 5 years. Additionally, in adjusted analyses, results indicated those with prostate cancer were at a 48% greater is of deep vein thrombosis (HR, 1.48 [95% CI, 1.39-1.57])and a 47% greater risk of pulmonary embolism (HR, 1.47 [95% CI, 1.39-1.56]) than their counterparts without prostate cancer.

In the latter portions of their study, investigators pointed out there were multiple limitations within the design of their study to consider when interpreting the results of their work.

“Although we were able to adjust our risk estimates for several patient variables, including comorbidities, medications and sociodemographic factors, lack of information on height, weight, smoking status and alcohol intake may have led to residual confounding,” investigators wrote.

This study, "Risk of venous thromboembolism in men with prostate cancer compared with men in the general population: a nationwide population-based cohort study in Sweden,” was published in BMJ Open.