Tackling antibiotic resistance – the impact for cancer patients

18 Dec 2014
Written by
Professor Peter Johnson

Last month marked the opening of Longitude Prize – competitors can now submit their innovative ideas to help tackle a global challenge: that of antibiotic resistance. This could pave the way to revolutionising healthcare for millions of people around the world. 

The emergence of bacteria that are resistant to antibiotics poses a major threat to human health – antibiotics are the main line of defence when our immune system is overwhelmed by bacteria. Bacterial infections can affect anyone, but the old, the young and the sick are particularly vulnerable. And that’s why this global prize could have a big impact for cancer patients. That’s a big group of people; there are more than 30 million people worldwide affected by cancer and this number is set to continue rising. 

People with cancer often become much more susceptible to infections for several reasons. Firstly, any type of cancer is a major cause of stress on the body, and this has the effect of lowering immune defences. Cancers of white blood cells, like leukaemia and lymphoma, have the greatest impact by directly affecting the immune system.   

On top of this, the treatments used to tackle cancer can often put the immune system under more pressure. Major surgery puts a great strain on the body: as well as leaving wounds which can harbour infection, there is a more general effect on the immune response, leaving people vulnerable to bacteria.

Radiotherapy – especially if it has to cover large areas of the body– and chemotherapy can both suppress the bone marrow cells that make our infection-fighting white blood cells.  This too can leave people with a reduced capacity to fight bacteria, something which is more of a risk if the natural barriers to infection such as the lining of the intestine and the skin are made fragile by treatment.  At the most extreme, a bone marrow transplant has to re-set the entire immune system, leaving patients vulnerable to many types of infection.

This lowering of immune defences can sometimes be life threatening for cancer patients. It also puts a great strain on the NHS; picking up an infection is the main cause of hospitalisation during chemotherapy treatment.

According to reported figures, as many as one in five cancer patients undergoing treatment are hospitalised due to infection. One way to lower the risk for some patients is with immune boosting drugs to encourage the bone marrow to make white blood cells faster, and there’s evidence this can reduce the number of patients needing to come into hospital1.  Sometimes, if we know a certain cancer treatment will make a person’s immune system dangerously low, we can pre-emptively give them antibiotics to reduce their risk of getting infected2. The trouble with this approach is that the more we use antibiotics, the more we favour growth of hardier strains – this is where antibiotic resistance comes from. So we need to use them sparingly and wisely.

So you can see susceptibility to infection is major concern for cancer patients, and our main line of defence against bacterial infections is antibiotics. The problem is that we’re more often seeing bacteria that are resistant. If a patient becomes infected with resistant bacteria and doesn’t have a strong enough immune system to fight them off, even aggressive antibiotics won’t be enough to save them, and there are no other effective options.

Most life-threatening infections in cancer patients are caused by common bacteria that would normally cause us no harm. These are the bacteria that happily live on our skin, in our throats, or in our bowel.  The biggest risk is when these bacteria make their way through a damaged area such as the lining of the intestine into the bloodstream, where they can overwhelm the body’s defences with dangerous and sometimes fatal results.

Hospitals take this threat very seriously and infection control measures are strict. For cancer patients, particularly those who have had surgery, have an IV line, a catheter, or a tracheostomy, precautions are taken to try and protect them from the bacteria that can colonise any point of weakness.

But to reduce the number of deaths from infections, we really need two things. Firstly, tests to speed up the accurate diagnosis of what infection a patient has – this way doctors could give them the most effective antibiotics earlier. And secondly, better treatments against antibiotic resistant bacteria – we need a last line of defence, something to give patients if all else fails. 

The war against bacteria is fairly balanced – we’re good at making new types of antibiotics when there’s the drive to do so. The trouble is, there’s been little commercial interest in antibiotic development and the field has been somewhat neglected. What we need now is a serious injection of time and money, and this is where the Longitude Prize could make a big difference. 

It’s important to nearly all areas of complex medicine that we galvanise interest in finding new ways to kill bacteria. As the population ages, chronic illnesses are becoming more common, increasing our need for antibiotics. And this includes cancer patients too. It’s crucial that we stay ahead of the game and invest in better antibiotics.  

Tackling the big picture questions and addressing the key problems the world faces is never going to be an easy task. But it’s something we need to aspire to do. At Cancer Research UK we’re also looking for innovative, Grand Challenge approaches to funding cancer research on a truly global scale: international, multi-disciplinary teams working together to tackle the biggest problems standing in the way of beating cancer. You’ll hear more details from us next year.

  

References:

Pfeil AM, Allcott K, Pettengell R, Minckwitz G, Schwenkglenks M, Szabo Z, 2014, Supportive Care in Cancer, Support Care Cancer. 2014 Oct 7

Leibovici L, Paul M, Cullen M, Bucaneve G, Gafter-Gvili A, Fraser A, Kern WV, Cancer. 2006 Oct 15;107(8):1743-51