Survivors from a wide range of cancers are more likely than people in the general population to be hospitalised or die from seasonal influenza even several years after their cancer diagnosis, warn researchers, including one of Indian-origin. The study, published in the journal EClinicalMedicine, suggests that cancer survivors are also likely to be at higher risk of severe Covid-19 outcomes. The research team from the London School of Hygiene & Tropical Medicine (LSHTM), analysed medical records from 1990 to 2014 of more than 630,000 people in the UK, including over 100,000 survivors of a range of cancers.

Comparing the rates of influenza hospitalisation and death between cancer survivors and the cancer-free population, they found that the risk of these outcomes was more than nine times higher in survivors from lymphomas, leukaemia, and multiple myeloma, compared to those with no prior cancer.

Crucially, this raised risk persisted for at least 10 years after cancer diagnosis.

Despite the risks being raised compared to the general population, the absolute risks of developing severe flu were still relatively low, with about 1 in 1000 survivors of these types of cancer hospitalised with flu each year.

Survivors from other types of cancer also had more than double the risk of severe influenza outcomes for up to five years from diagnosis.

These findings persisted even after accounting for other suspected risk factors such as old age, smoking, socioeconomic status, body mass index and other illnesses.

The researchers also found that cancer survivors were more likely to have other diseases that are associated with increased risk of severe Covid-19 outcomes, such as heart disease, diabetes, respiratory disease and kidney disease. “These findings have an immediate relevance as we enter the winter period: we have a flu vaccine available, and the likelihood of a Covid-19 vaccine in the near future,” said study author Krishnan Bhaskaran from LSHTM.