Thrombosis Australia presented a webinar with Professor the Lord Kakkar (Professor of Surgery, University College London), and Associate Professor Dr Vivien Chen (University of Sydney) to discuss relevant information and current research related to Cancer and Thrombosis.

The session was moderated by Dr Harry Gibbs. Dr Gibbs is an Associate Professor of Medicine at Monash University, Deputy Director of General Medicine and the Medical Director of the Vascular Laboratory at the Alfred Hospital and Director of Medicine at Sandringham Hospital in Melbourne.

These are a few topics of interest covered during the webinar.

Professor the Lord Kakkar started the conversation with the important question about why cancer patients have an increased risk for the development of thromboembolic complications.

Research over the last 25-30 years has attempted to address this situation. There are tumour derived mechanisms for heightening thrombosis risk, there are treatment considerations and there will also be intrinsic issues to the patient. There is a complex interaction between coagulation biology and tumour biology but beyond that there will be anatomical reasons why cancer patients will develop thrombosis – a large tumour or mass in the pelvis compressing some of the great veins will result in venous obstruction and therefore a heightened risk for DVT in the legs. The mechanisms associated with increased post-operative thromboembolism risk among non-cancer patients are exaggerated in cancer patients – the immobility and trauma of surgery activating systemic coagulation. Other interventions – systemic therapies, genetic factors, mutations in tumour cells. There is a multifactorial explanation for the substantial risk seen in cancer patients. Some studies have suggested up to 20% of cancer patients, at some time through the natural history of their disease will experience a thromboembolic complication.

Dr Gibbs mentioned the development of thrombosis is a poor prognostic feature in cancer patients. Lord Kakkar discussed a number of pieces of evidence has established the validity of this observation. A study in Denmark approximately 20 years ago found that patients which presented with cancer and thrombosis had a poorer survival at 12 and 36 months compared to those with cancer alone. A New York study also found a similar observation with cancer patients who developed post-operative DVT or pulmonary embolism after major abdominal surgery for their malignant disease had a poorer disease-free survival and overall survival compared to those patients who did not develop thrombosis in the early post-operative period.

Dr Vivien Chen was asked if it is beneficial to look for cancers among patients who present with unprovoked VTE, under what circumstances would this occur and what investigations would be carried out? There is an association between unprovoked VTE and up to 10% have been found to have an active cancer within that 12-month period post first diagnosis of the unprovoked VTE. Dr Chen looks at the history and examination of her patients who present with unprovoked VTE. If there are any signs which would make you want to look for alarm symptoms, recommending appropriate malignancy screening. RCTs show that we don’t necessarily improve the outcomes for the patients by doing full screening of asymptomatic patients. Discussing with patients the risk of thrombosis and performing the appropriate cancer screening for the individual.

Are there patients with cancer associated VTE you would not prescribe a DOAC? The patients Dr Chen would not start on a DOAC would include those who would not be able to achieve adequate levels, for example drug-drug interactions or absorption may be an issue in some patients.

Is there real-world evidence which confirms the findings of the RCTs to provide some comfort in prescribing these drugs to patients with cancer? There are studies outside the RCT setting using a variety of methodologies and yes, these studies do confirm the efficacy of DOACs for managing cancer associated thrombosis.

The conversation also includes discussions regarding specific types of DOACs, the use of IVC filters, drug levels and bleeding, extended duration therapy.

To watch the webinar in its entirety, please click this link