Venous thromboembolism and cyproterone acetate in men with prostate cancer: a study using the General Practice Research Database.
OBJECTIVE
To evaluate the risk of venous thromboembolism (VTE) associated with the use of cyproterone acetate (CPA) amongst men with prostate cancer.


METHODS
Using data from the General Practice Research Database, cases of VTE were identified amongst men with prostate cancer. Four controls with no evidence of a VTE were selected for each case. The time from diagnosis of prostate cancer to first hormonal treatment, and from first hormonal treatment to VTE, was compared for different treatments. Adjusted risk estimates for VTE were derived from further analysis using a nested case-control study design amongst all men with advanced prostate cancer, qualified by evidence of hormonal treatment.


RESULTS
The time between diagnosis and first treatment was significantly shorter for men first treated with CPA than for men first treated with a luteinizing hormone releasing hormone (LHRH) analogue (adjusted hazard ratio 1.33, 95% confidence interval, CI, 1.06-1.67). When the first treatment was CPA, the treatment-free period after diagnosis was significantly shorter for men who later had a VTE than for those who did not. The case-control study yielded an adjusted risk estimate for VTE amongst CPA users that was significantly higher than amongst men who were prescribed an LHRH analogue or who had had an orchidectomy (adjusted odds ratio 5.23, 95% CI 3.12-8.79).


CONCLUSIONS
There was a greater risk of VTE associated with CPA, which might be due to differences in disease severity between users of different products. The clinical significance of this finding is unclear.
Seaman
Helen E
HE
Department of Pharmacoepidemiology, Postgraduate Medical School (University of Surrey), Guildford, UK. h.seaman@surrey.ac.uk
Langley
Stephen E M
SE
Farmer
Richard D T
RD
de Vries
Corinne S
CS
D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000009:adverse effects*; D016022:Case-Control Studies; D015331:Cohort Studies; D017373:Cyproterone Acetate / Q000009:adverse effects*; D019992:Databases as Topic; D005194:Family Practice; D006801:Humans; D008297:Male; D008875:Middle Aged; D009919:Orchiectomy; D011471:Prostatic Neoplasms / Q000188:drug therapy* / Q000601:surgery; D012307:Risk Factors; D012720:Severity of Illness Index; D016019:Survival Analysis; D013923:Thromboembolism / Q000139:chemically induced* / Q000401:mortality; D020246:Venous Thrombosis / Q000139:chemically induced* / Q000401:mortality
D000970:Antineoplastic Agents; D017373:Cyproterone Acetate