Relics of ancient viruses - that have spent millions of years hiding inside human DNA - help the body fight cancer, say scientists.

Axar.az reports that the study by the Francis Crick Institute showed the dormant remnants of these old viruses are woken up when cancerous cells spiral out of control.

This unintentionally helps the immune system target and attack the tumour.

The team wants to harness the discovery to design vaccines that can boost cancer treatment, or even prevent it.

The researchers had noticed a connection between better survival from lung cancer and a part of the immune system, called B-cells, clustering around tumours.

B-cells are the part of our body that manufactures antibodies and are better known for their role in fighting off infections, such as Covid.

Precisely what they were doing in lung cancer was a mystery but a series of intricate experiments using samples from patients and animal tests showed they were still attempting to fight viruses.

"It turned out that the antibodies are recognising remnants of what's termed endogenous retroviruses," Prof Julian Downward, an associate research director at the Francis Crick Institute, told.