Cancer signs can appear long before diagnosis

New research led by the Francis Crick Institute has claimed that early signs of cancer can appear years before diagnosis and developing tests for these genetic signs could provide new ways to spot cancer early.

Published in Nature, the study analysed 47 million genetic changes in more than 2,500 human tumours, across 38 cancer types. By looking at how many times a single change had been replicated and copied across chromosomes, the researchers were able to determine the order in which they happened and the relative timing between them.

The research discovered that just over 20 per cent of mutations can be considered early events in a tumour’s development, with some of these changes taking place years, even decades, before the cancer is found. Half of these fall within the same nine genes, meaning there is a small number of genes that are common drivers of early cancer development.

Peter Van Loo, co-lead author, said: “We’ve developed the first timelines of genetic mutations across the spectrum of cancer types. For more than 30 cancers, we now know what specific genetic changes are likely to happen, and when these are likely to take place. Unlocking these patterns means it should now be possible to develop new diagnostic tests, that pick up signs of cancer much earlier.”

The research identified cancer types in which mutations tend to happen particularly early, for example, ovarian cancer and two types of brain tumours, glioblastoma and medulloblastoma. It also revealed the specific changes that are likely to happen early in each of the more than 30 cancer types. One of the most common early changes in many cancers, including ovarian cancer, affects a gene called TP53. In glioblastoma, an extra copy of chromosome 7 is very frequently gained early, while for pancreatic neuroendocrine cancer a number of chromosomes are lost in the initial stages of tumour development.