Practical guidelines to assist in the treatment of cancer-associated thrombosis (CAT) have been developed by an expert working group of haematology, oncology and pharmacology clinicians.

Consensus recommendations, published in Critical Reviews in Oncology/Haematology were reached for managing patients with: gastrointestinal impairment; impaired renal function; impaired liver function; those at increased risk of bleeding; patients at risk of drug-drug interactions; those with very high or low body weight and CAT; anticoagulation for VTE in presence of primary or secondary brain tumours; extended duration of anticoagulation beyond 6 months; and management of recurrent VTE.

Explaining the rationale behind the move, the authors said treatment decisions for CAT had become increasingly challenging with the introduction of direct oral anticoagulants (DOACs).

Also, existing guidelines “are limited to evidence from patients meeting stringent trial-entry criteria”, thus omitting those with complex and multiple co-morbidities, such as low platelet count, drug interactions and renal impairment, as encountered in real-life settings.

Given that CAT remains a leading cause of death in cancer patients, the authors sought to develop a “user-friendly and practical algorithm” for both the treatment and secondary prevention of CAT, following a series of virtual meetings in which the group considered the most pertinent clinical questions that needed addressing.

For example, for anticoagulation in the presence of thrombocytopenia, the authors recommend that patients with a platelet count of more than 50 × 109/L should be fully anti-coagulated, while for those with a high risk of further thrombosis (eg, a VTE event in the prior 4 weeks) and platelets of less than 50 × 109/L, clinicians should consider platelet transfusion support and full anticoagulation with low molecular weight heparins (LMWH). For lower risk patients (eg. more than 4 weeks from the VTE event), a 50% dose reduction in LMWH should be considered if platelets are 25-50 × 109/L and withheld if less than 25×109/L.

Elsewhere, patients who have no absolute bleeding risk contraindication should be fully anticoagulated, with anti-Xa DOAC the preferred option. However, LMWH are the preferred choice for patients with gastrointestinal tract or genitourinary malignancy that remains in situ. For CAT patients with an absolute bleeding contraindication, such as the presence of active bleeding, and a high risk of thrombosis, physicians should consider use of a retrievable IVC filter, which should be removed and anticoagulation resumed once the bleeding is resolved.

With regard to longer-term anticoagulation, the group recommended that patients with CAT should undergo “expert clinical review” after six months’ treatment with therapeutic anticoagulant therapy, “to determine whether continuation of anticoagulant treatment is warranted”. Factors such as the type of cancer, life expectancy, bleeding risk and quality of life should be taking into account when making the decision.

“These algorithms and recommendations provide a scaffold for healthcare professionals to tailor their anticoagulation choices, and identify areas of uncertainty where shared decision making, such as with the multi-disciplinary team, may be appropriate,” the authors concluded, but also stressed that “prioritising patient choice must be central” to CAT related treatment decisions.