Are We Aware of the Increased Risk of Thrombosis (Clotting) in Cancer Patients?

More than 70% of cancer patients do not know that they are at greater risk of deep vein thrombosis (clotting in deep veins—DVT) than the general population. This is because specialists do not discuss the issue with them.

What Is Thrombosis?

A mass of clotted blood forming inside a blood vessel is called thrombosis. In Turkish, the term thrombus is also used. This blockage inside a blood vessel consists roughly of platelets, red blood cells, and fibrin fragments.

Above is a scanning electron microscope image of a thrombus (clot)—platelets, red blood cells, and fibrin fibers—at approximately 5500 times magnification.

The Tendency Toward Thrombosis Increases in Cancer

This link between cancer and thrombosis, and awareness among patients and healthcare professionals, was explained by the results of a survey conducted by the European Cancer Patient Coalition (ECPC).

The researchers wrote about their study: “The aim of this pan-European patient survey was to assess patients' awareness and knowledge of cancer-associated thrombosis (CAT), including risk factors, signs, symptoms, and interventions, to improve CAT prevention and treatment.”

A group including oncology healthcare professionals, policymakers, and patient representatives met to discuss and review continuing concerns about the high morbidity (illness) and mortality (death) associated with thrombosis in cancer patients.

These discussions showed that there had been very little improvement over the years in awareness of thrombosis risk in cancer, and that healthcare professionals and patients still needed more information about CAT, particularly regarding primary and secondary prevention of thrombosis.

The idea for a pan-European survey emerged from this starting point. The European Cancer Patient Coalition (ECPC), broadly representing a collective voice for cancer patients in Europe, led the survey. It was conducted in six countries (France, Germany, Greece, Italy, the United Kingdom, and Spain) and included 1365 patients and healthcare professionals. The original ECPC survey results were published on World Thrombosis Day in late 2018.

Thrombosis Occurs in 1 in Every 5 Cancer Patients

A professor of hematology at the University of Milano-Bicocca in Italy and one of the study authors, Dr Anna Falanga, assessed the findings in an interview and explained how knowledge of CAT could be improved among cancer patients.

“The data tell us that approximately 20% of cancer patients will experience venous thromboembolism (VTE), which is about 4–5 times the rate in the general population.”

Falanga also said of the relationship between cancer and thrombosis:

“We have known about the link between cancer and thrombosis since the 19th century, but it took until the middle of the last century to reach our current level of understanding and awareness of the problem. Initially, it was limited to basic research, with major advances in understanding the mechanisms linking the two; only recently have we had clinical studies attracting healthcare professionals who had not previously been interested in the subject.”

• Related topic: What Is Trousseau's Sign? Where Does Its Name Come From?

What Do Patients Know About Cancer-Associated Thrombosis?

Some data from the European survey showed that nearly three-quarters of respondents (72%) had not known before taking the survey that people with cancer were at greater risk of developing thrombosis than people without cancer.

According to the authors, “We asked participants to rate their knowledge of CAT on a scale from 1 to 10, and obtained an average score of 4.1. Only 21% of patients gave a score of 7 or above (quite knowledgeable). The results were very similar across surveys in different countries .”

They also reported that the survey assessed how much information their own doctors had given them about the subject. Approximately 35% of patients had been informed about CAT either immediately before or at cancer diagnosis. Particularly worryingly, a quarter of respondents (26%, a substantial proportion) reported first learning about CAT when they experienced a blood clot problem. These proportions were also very similar on average across the countries surveyed.

Falanga explains, “Remember that cancer and cancer treatments cause a range of side effects, some of which can be quite serious; in some situations, a clot may be seen as a minor problem. In reality, it is not. A clot can be a serious cause of illness or death in cancer patients .”

Do You Know How to Prevent Thrombosis?

When discussing prevention:

• most participants (87%) knew that going for a walk could reduce the risk
• ; a slightly smaller proportion (75%) knew that quitting smoking,
• a somewhat smaller proportion (63%) knew that avoiding dehydration and drinking plenty of water, and
• 55% knew that stretching the legs could reduce the risk

Participants appeared relatively well informed about CAT symptoms:

• 73% of survey participants identified swelling in the feet, ankles, or legs as a possible sign of DVT, while
• 71% identified shortness of breath as a possible sign of pulmonary embolism (PE, a blockage of a blood vessel in the lung).

However, the authors say other symptoms were less well known.

“Just over half of participants (57%) knew that pain, cramping, and tenderness could be symptoms of DVT, and approximately one-third (33%) knew that an irregular heartbeat could be a symptom of PE. These results vary between countries.”

The survey indicated that more than one-third of participants were already taking anticoagulants (blood thinners), but almost all (96%) said they knew anticoagulants could be effective in treating thrombosis. Only 41% of those taking anticoagulants said they had been informed about possible side effects.

Survey Results in Italy

The report containing the full European survey results provided further detail. The overall results also included findings for each individual country.

Italian data from 246 people showed that only 27% of patients and healthcare professionals were aware of the increased thrombosis risk after a cancer diagnosis. Although the score for Italy on a 10-point scale was lower (3.3/10 vs. 4.1/10), it was similar to the overall survey results.

Results differed more in knowledge of risk factors. Most participants (89%) knew that remaining inactive was one of the main thrombosis risks. However, just over half said they knew radiotherapy was a risk factor. Meanwhile, 75% of participants knew that cancer surgery and chemotherapy were risk factors.

Falanga says, “For all intents and purposes, all types of cancer drugs significantly affect the risk of developing blood clots, and this also applies to modern types of treatment such as immunotherapy .”

Answers to questions about symptoms showed that 58% of Italian patients and healthcare professionals knew swelling in the lower legs could be a symptom of DVT, and the same percentage knew shortness of breath could be a symptom of PE.

The picture in Italy was somewhat mixed for preventive actions: 74% of participants knew the importance of walking, but a slightly smaller proportion (57%) knew they should stop smoking, and fewer (35%) knew they should stretch their legs. Among Italians, 41% said they took anticoagulants, and 53% of these said they were informed about the potential adverse effects of such drugs.

Where Are We Heading? What Can Be Done?

The researchers write that “the high CAT rate indicates that CAT prevention and recognition remain low among healthcare professionals, despite clinical evidence and clear guideline recommendations for cancer patients .”

The ECPC survey results also confirm previous studies highlighting patients' lack of knowledge about CAT and the need for more extensive discussions between doctors and patients.

So what can be done? As emphasized in previous studies, “Patients' experiences are an education in themselves, particularly for the oncology care team. When a patient experiences a thrombosis problem, the opportunity to prevent thrombosis—which should be a major focus of care clinics (surgery, oncology, and palliative care)—is lost.”

Falanga said, “Oncologists, as well as other teams responsible for patient care (such as surgeons and nurses), must do their best to promote CAT awareness and awareness of the risk of developing blood clots at every stage of the patient's cancer journey .” Falanga explained that doctors should be the first people to communicate in this group. “These professionals are on the front lines of treatment: they are among the first healthcare workers to raise the possibility of a suspected clot, so they must be fully aware of the increased risk in oncology patients.”

As oncology professionals, we agree that a multidisciplinary approach is extremely important here, but the team's different roles must be clear. It is also necessary to establish who does what in informing and educating the patient. Oncology nurses can fill an important gap in education on this subject.