Surgery and risk of venous thromboembolism in women with cancer: a UK-based prospective cohort study
It is known that the incidence of venous thromboembolism (VTE) is increased in people with cancer and that surgery is also a major risk factor. However, less is known about how the risk varies by cancer type or how much of this increased risk is due to cancer-related surgery. This study aims to describe the incidence of VTE in relation to cancer type, taking different types of surgery into account.
METHODS:
1.3 million UK women were recruited into the Million Women Study through the NHS Breast Screening Programme in 1996-2001. These women are being followed by record linkage to routinely collected inpatient and day-case NHS hospital admissions data, cancer registrations and death records. The relative risks (RRs) and 95% confidence intervals (CIs) of an inpatient/day-case hospital admission or death record for VTE (ICD10 codes I26,I80-I82) were estimated in relation to a variety of malignancies. Further analyses will investigate how different surgical procedures can affect these risks.
RESULTS:
Among 1,198,848 women with no previous VTE or cancer and an average of 11.7 years of follow-up per woman, 108,607 (9%) had a hospital admission for incident cancer and 21,501 (1.8%) had a hospital admission or death from VTE, including 5,251 women whose VTE followed cancer. Overall, women were more than eight times more likely to have a hospital admission for VTE after cancer than without (or before) any cancer diagnosis (adjusted RR=8.7, 95%CI:8.4-9.0). A preliminary analysis by cancer type found the highest relative risks (over 60-fold) associated with cancers of the brain and pancreas. Results will also be presented taking surgical procedures into account.
CONCLUSIONS:
The risk of VTE is significantly increased following a cancer diagnosis. This study has sufficient power to investigate in detail how these risks differ by type of cancer, whilst allowing for the risks associated with surgery.