DNA footprints of ancient viruses may boost cancer treatment

London, April 17 Remnants of ancient retroviruses passed down in our DNA could be an effective target for antibodies against lung cancer, according to researchers.

The early genetic clues could indicate where and when cancer cells might spread next, said researchers from the Francis Crick Institute and University College London and Cancer Research UK.

The study, published across seven papers in the journal Nature and Nature Medicine, could pave the way for doctors to use blood tests to predict cancer's future, monitor it in real-time and adapt treatments accordingly.

It also offers the possibility of clinic being able to analyse the disease's risk of returning following surgery.

The study, analysed the tumours of 421 patients with non-small cell lung cancer the most common form of the disease from when they were diagnosed to monitor how the tumours changed over time.

In the papers, the researchers describe how changes to cancer cells' DNA are enabling them to anticipate how those cells will behave in the future. This includes where and when cancer will spread to other parts of the body in a process known as metastasis, which is responsible for most cancer deaths worldwide.

While the research was carried out on patients with lung cancer, the findings can be applied to other cancer types, such as skin cancer or kidney cancer.

The study "recognises that cancer is not static and the way we treat patients shouldn't be either," said lead researcher Professor Charles Swanton from UCL Cancer Institute, the Francis Crick Institute and Cancer Research UK.

"By looking at the tumour in its entirety, we can observe how these cell populations interact and even compete with one another, which is helping us to glean valuable insights into the likelihood that a tumour will return and when this might happen.

"We can also observe how the tumour is likely to evolve over time, spread and respond to treatment, offering hope to millions of patients in the future," Swanton said.

Currently, the best option to monitor a patient's tumour is to extract tissue either through a biopsy or during surgery. Both are invasive and time-consuming options which give a limited snapshot of how that tumour is behaving at a given point in time.

In the study, analysing DNA released into the bloodstream from tumour cells, known as circulating tumour DNA (ctDNA), researchers found that the presence of ctDNA in the blood before or after surgery suggested that the patient's cancer was highly likely to return in the future.

The presence of tumour DNA in the blood isn't the only indicator that cancer might spread or come back. Researchers found the microscopic patterns created by the arrangement of tumour cells are also linked with the risk of cancer returning.

"A blood test that reads ctDNA could let doctors track someone's cancer in real time, allowing them to personalise treatments to that patient," said Dr Iain Foulkes, Executive Director of Research at Cancer Research UK.