Risk for VTE Persists Over the Long Term for Survivors of Childhood Cancers

Survivors of childhood cancers appear to be at an increased risk for venous thromboembolism (VTE) across their lifespan, and a diagnosis of VTE increases mortality risk, according to a study published in the Journal of Clinical Oncology.  Researchers found that due to an increased risk for VTE, healthcare providers should discuss interventions that target potentially modifiable comorbidities, such as obesity. They suggest that healthcare teams develop individualized prophylaxis strategies.¹

“These results relate to the long-term risk of VTE in cancer patients out to 35 years from treatment,” said study corresponding author Christopher B. Weldon, MD, PhD, of the Department of Surgery, Boston Children’s Research Hospital, Boston, Massachusetts.

THE STUDY

Dr Weldon and his colleagues conducted a multi-institutional cohort study of 24,355 5-year survivors of childhood cancers, entitled The Childhood Cancer Survivor Study. All the patients’ diagnoses were made between 1970 and 1999, and 5051 sibling participants were also included. The median age at last follow-up was 28.7 years (range, 5.6 to 58.9 years) and the median follow-up since diagnosis was 21.3 years (range, 5.0 to 39.2 years). In this cohort, 19% of the cancer survivors were of an ethnic or racial minority and 46% were female.

The primary outcome was self-reported late VTE occurrence 5 years or later after cancer diagnosis. The secondary outcome was nonexternal cause late mortality. This was defined as a death not due to a result of external causes, such as accidents, injuries, or suicide.

Within 5 years of a primary cancer diagnosis, the researchers reported 229 VTE occurrences in 24,355 survivors, and 451 late VTE occurrences. Late VTE incidence among survivors was 1.1 events per 1000 person-years and 0.5 events per 1000 person-years for siblings (relative risk [RR]: 2.2). There were 2.5 excess events per 100 survivors over 35 years of follow-up.

When the investigators looked at risk factors, they found that female sex (RR, 1.3), cisplatin (1 to 199 mg/m² (RR, 3.0), cisplatin 200 to 399 mg/m² (RR, 1.9), cisplatin greater than 400 mg/m² (RR, 2.0) were significant risk factors. L-asparaginase (RR, 1.3), obesity or underweight (increasing risk with increasing body mass index), and late cancer recurrence or subsequent malignant neoplasm (RR, 4.6) were also significant risk factors.

Limb salvage (reference amputation; RR, 3.1) and cisplatin 200 to 399 mg/m² (RR, 4.0) and cisplatin more than 400 mg/m² (RR, 2.9) were independently associated with late VTE among lower-extremity osteosarcoma survivors. The researchers also found that patients who experienced a VTE were at an increased risk of non-external cause late mortality (RR, 1.9).