Let’s start with a quick wake-up call : multiple myeloma is associated with a 9-fold increase in the risk of having a venous thromboembolism (VTE) or in layman’s terms a blood-clot that forms in a vein and that migrates to another location. Blood-clots cause all sorts of problems with the best known probably being stroke. Both the Association of Clinical Oncologists (ASCO) and the International Myeloma Working Group (IMWG) have recommended in the past that select MM patients be given ‘thromboprophylaxis’. This dynamite Scrabble word means therapy to prevent blood-clots from forming. ASCO recommends low-molecular-weight heparin injections (brand name Lovenox or generic name enoxaparin) or low-dose aspirin in patients receiving immunomodulatory drugs (IMIDs) in combination with chemotherapy and/or dexamethasone. The IMWG has recommended low-dose aspirin for MM patients with one or no VTE risk factors including those on lenalidomide in combination with low-dose dexamethasone, melphalan or doxorubicin. A paper presented at ASH 2017 has now raised some questions about the adequacy of aspirin. The authors reviewed records of nearly 5,000 MM patients that had been treated for myeloma within the US Veterans Health Administration System of whom 582 developed VTE. Risk factors for VTE after a myeloma diagnosis included : history of prior VTE, lenalidomide and thalidomide. Some patients were treated with warfarin to prevent blood-clots, others had been given low dose aspirin. Key results are :

• ‘ … aspirin was not associated with a decreased risk of VTE.’
• ‘Warfarin use was associated with a trend towards reduction in risk of VTE.’
• ‘Lenalidomide, thalidomide, and a prior VTE increased the risk of VTE after MM diagnosis. Patients with such history should be considered high risk for VTE. In this high-risk population, aspirin may not provide adequate thromboprophylaxis.’ [Emphasis added]

offers an additional perspective about the potential use of rivaroxaban (brand name Xarelto) as an alternative. There are some interesting comments made in this paper :

• ‘Unlike low-molecular weight heparins (LMWHs) which represent the current standard-of-care for cancer-associated venous thromboembolism (CAT) management, rivaroxaban can be administered orally, avoiding the need for uncomfortable injections.’ [emphasis added]
• ‘Event rates observed in this rivaroxaban treated cohort were consistent with those observed in prior studies of LMWH- and rivaroxaban-managed CAT patients. Our data may provide some reassurance to clinicians regarding the effectiveness and safety of rivaroxaban in treating CAT patients in routine outpatient practice.’

In a nutshell: injections of enoxaparin (low molecular heparin) is considered the current standard of care for cancer associated blood-clots, low dose aspirin may not do the trick but Xarelto may be an option. So, the question for the patient is: do you want to mess with a proven standard-of-care and its daily bee-sting or migrate to something else that you can pop with all the other oral drugs you already take, just for the sake of convenience? Something to discuss with your physician.