Petri dishes pictured in an unknown location in a Cancer Research UK laboratory on an unknown date (Reuters)

A new study found that remnants of ancient viruses that have been passed down by humans over thousands or even millions of years may aid in the fight against cancer.

To understand why some patients respond to immunotherapy more favorably than others, researchers at the Francis Crick Institute were examining lung cancer, the biggest cause of cancer-related deaths worldwide.

They discovered through their study, which was just published in Nature, that malignant cells can trigger the dormant remnants of ancient cells. This could unintentionally assist the immune system in identifying and attacking the tumor.

The "fascinating" discoveries, according to scientists, could be used to improve cancer treatment or possibly prevent lung cancer in some cases.

The immune response in question featured white blood cells called B lymphocytes (B cells), which gathered near tumors. According to the researchers, this happens because cancer reactivates the viral DNA, which draws the immune system's attention.

"The immune system is tricked into believing that the tumor cells are infected and it tries to eliminate the virus, so it's sort of an alarm system," Professor George Kassiotis, head of the Laboratory of Retroviral Immunology at the Francis Crick Institute, said as quoted by a British media outlet.