A new Blood Advances study suggests that people with cancer and non-O blood types, such as types A, B, and AB, face an increased risk of developing venous thromboembolism (VTE), or blood clots in the veins, three months after their initial diagnosis. Scientists have long strived to understand the risk factors for VTE, the leading cause of preventable hospital deaths in the United States. Existing assessments use factors like tumor or cancer type to detect those at high risk of VTE. Yet, many patients without these diagnoses still develop life-threatening blood clots but go unidentified.