by Mikail Gögenur, PhD student, MD

Surgery is the only treatment that today can cure patients with colorectal cancer. However, up to 30% of patients experience a relapse of their cancer following curative-intended surgery. Relapse is the leading cause of death after cancer surgery, while a surgery-induced dysfunction in the immune system is hypothesized to be the cause of it. Research into modulating the immune system so this dysfunction is lessened has revealed an unlikely candidate, the influenza vaccine, which can induce changes in the immune system in favour of anti-cancer activity.

We sought to investigate this in a nationwide register-based study to see if indeed receiving an influenza vaccine in close relation to curative surgery for cancer had an association with risk of all-cause and cancer-related death. We included over 20.000 patients where 2.500 patients received the vaccine with six months after surgery. Interestingly, we found that patients that received an influenza vaccine within six months after surgery were associated with an 11% reduced risk of all-cause death and a 18% reduced risk of cancer-specific death compared to patients that did not receive a vaccine. When only looking at patients receiving the vaccine within 30 days after surgery, the association was 18% and 30% reduced risk of all-cause and cancer-specific mortality, respectively. There was no association when looking at patients receiving the vaccine one to six months after surgery.

This indicates that the well-known influenza vaccine has an association with key outcomes for patients with cancer when given in close relation to curatively intended surgery.

The prospect of being able to induce favourable changes in the immune system with, the influenza vaccine is very interesting, as current immunotherapy regimes have frequent and serious side effects while only being effective in a subset of patients. The influenza vaccine is already recommended to patients with cancer, so concerns of side effects or complications are minimal.

To further argue that the influenza vaccine should be investigated for its anti-cancer immune properties, are the recent mouse studies showing that local intratumoral application of the influenza vaccine shrinks both treated and untreated tumors, thus indicating that local influenza vaccine treatment creates a systemic response against cancers.

We have, therefore, decided to take the important step and investigate whether an intratumoral application of the influenza vaccine in patients with colorectal cancer is, first of all safe, but also if we can detect immune changes that favor the patients. We look forward to this study and expect to report the results within the next year.