Understanding why this happens – and how we can treat tumours once they have spread – is crucial if we are to beat cancer.
Cancer is not just one but hundreds of different diseases, depending on where in the body it started and the underlying molecular faults that drive it.
Over the years, many researchers have poured their efforts into understanding individual types of cancer - such as the recent work from Cancer Research UK’s Professor Carlos Caldas showing that breast cancer can be divided into ten distinct types – as well as searching for the fundamental characteristics of cancer cells (for example, our very own Sir Paul Nurse and Sir Tim Hunt’s Nobel prize-winning work on understanding how all cells divide).
Much of the effort in developing new cancer treatments has focused on identifying and targeting specific molecules in cancer cells – good examples of this approach in action are revolutionary ‘targeted’ drugs like breast cancer drug trastuzumab (better known as Herceptin) and leukaemia drug imatinib (also called Glivec).
But as well as this focus on cancer cells themselves, it’s becoming increasingly clear that tumours are more than just collections of rogue cells. Blood vessels, immune cells and other healthy tissues are hijacked to support a tumour, helping it grow, spread and resist treatment.
Researchers are increasingly turning their attention to this ‘bad neighbourhood’ around a around a tumour, to understand how it can be brought back under control to treat cancer more effectively.
There’s more to cancer than cancer cells
Solid tumours (cancers excluding those affecting the blood) can be thought of as being a bit like a rogue organ in the body, rather than a growing cluster of identical cancer cells.
So modern-day cancer research often involves studying this whole system in order to further our understanding of cancer and tackle it effectively.
All the different types of cells within tumours, the proteins that surround them and the conditions they create together are referred to by scientists as the tumour microenvironment.
This ‘neighbourhood’ includes blood vessels and lymphatic vessels (which carry a fluid called lymph, containing many of the components of our immune system). There are also cells and molecules from the immune system itself, and wound-healing cells called fibroblasts, as well as a sticky protein ‘glue’ (known as the matrix) that supports all of the cells and stops them from drifting apart when they need to be held together.
Can we target the microenvironment to treat cancer?
All of the different parts of the microenvironment play their own roles in helping tumours to grow, and while their importance is still to be fully understood, research is going strong in this area. Through looking in greater detail at the tumour microenvironment, we’ll be able to understand more about how tumours grow and spread, and how we can stop them.
For a personal view from one of our researchers working in this area, check out this interview with Professor Fran Balkwill at the Barts Cancer Institute in London. Professor Balkwill gives us her views on why it’s important to think about treating cancer and its environment together, and why she’s excited about it.
But that’s not all. Because this is such a hot topic in research, we’ve got a series of postscoming up about the tumour microenvironment and its importance in cancer research today, covering blood vessels, cancer spread and inflammation.
Watch out for them over the coming weeks, to find out more about this fascinating and important area.
Marianne Baker did her PhD at Barts Cancer Institute, funded by Cancer Research UK