Most cancers kill by spreading to other organs. Breast cancer, for instance, if it stayed at the original site, would cause a nasty ulcer, but this would not cause death. Surgery could cure every case. The problem comes when it seeds secondaries in places like the lungs or liver, co-opts the blood supply and eventually prevents an essential organ from doing its job. Result - another cancer death. Not surprising then that one branch of cancer research is trying to find out how this process takes place. How do those marauding cells break away and travel to far-flung parts of the body?
Surgery, radiotherapy and chemotherapy are a bit like tackling an overgrown garden - you can slash the weeds down, burn them off or spray them with weedkiller. Trouble is that you might also destroy attractive plants and helpful creatures in the process. These combined methods have saved many lives, including mine, but we all know that they are far from ideal and can cause a fair bit of collateral damage to healthy tissues.
So research these days delves into the most detailed, molecular level. Until you know the exact molecular interactions, you can't devise a treatment that could halt the progress of cancer in a focussed way, with limited side effects.
A team in Germany has just made progress in this area. They have discovered that some cancer cells use an immune system chemical to break through artery walls and gain access to the body's high-speed transport system - the blood.
There are many of these immune chemicals, known as chemokines or cytokines. Together they form a complex communication system that allows our millions of immune cells to communicate with the other cells in the body. When the immune system sets up an area of inflammation, some of these chemicals act on the walls of blood vessels, opening up gaps and allowing immune cells to move out of the blood and attack bacteria in the surrounding tissues. Normally blood vessels will allow simple molecules to pass through them, but not relatively huge objects like cells. During inflammation however, some of the body's largest cells can travel out of the blood system and into the tissues.
It seems that some cancer cells use this mechanism in reverse, using a specific immune chemical, opening up holes in nearby blood vessels and creating a route into the blood.
Painstaking research like this opens up the possibility of blocking the action of such chemicals and so outwitting more and more cancers.
Wolf et al. Endothelial CCR2 Signaling Induced by Colon Carcinoma Cells Enables Extravasation via the JAK2-Stat5 and p38MAPK Pathway. Cancer Cell, 2012; 22 (1):