- New research suggests hay fever sufferers are less likely to get certain cancers
- They back up other, smaller studies carried out since the link was first made
- One theory is that hay fever promotes something called immune surveillance
For around one in five of us, hay fever is an annual scourge that can ruin spring and summer. Some 13 million Britons suffer runny noses, incessant sneezing and itchy or streaming eyes triggered by pollen.
But for all the discomfort it brings, could there be an unexpected upside to hay fever (or allergic rhinitis, as doctors call it)?
New research suggests sufferers may be significantly less likely to develop certain cancers than those who breeze through the season unaffected by pollen-induced misery.
The research could lead to new treatments, such as drugs that rev up immune cells that are extra-active in those with hay fever [File photo]
The study, by a team at the U.S. National Cancer Institute, found rates of cancers of the throat, gullet, cervix and tonsils were reduced by up to a third in patients with a history of hay fever, compared with those who do not suffer.
The findings come from one of the largest studies ever to investigate the possible anti-cancer benefits of the common allergy.
They back up other, smaller studies carried out since the link between hay fever and protection against cancer was first made more than a decade ago.
The researchers monitored nearly 1.7 million people in the U.S. diagnosed with different cancers between 1992 and 2013 and compared them with hundreds of thousands of tumour-free volunteers of a similar age and sex.
Scientists think this high level of immune surveillance may mean the body’s defences are able to snuff out fledgling cancer cells before they can get a foothold [File photo]
They then matched hay fever rates in both groups and found significantly more cases among the cancer-free group.
The study, reported in the journal Cancer Epidemiology, Biomarkers & Prevention, also found asthma was linked with a small reduction in liver cancer risk.
Quite why hay fever, out of all the common allergic conditions, might have this effect is still not clear — nor why the condition seems to reduce the risk of some types of cancer and not others.
But one theory is that hay fever, more than other common allergies, promotes something called immune surveillance — in which the immune system scans the body for, and then destroys, cancerous cells.
When hay fever is triggered, the immune system mistakes harmless pollen as a threat and pumps out the chemical histamine to try to rid the body of the perceived intruder. Most people manage the resulting symptoms by taking anti-histamines.
These dampen the effects of the histamine ‘rush’, but the near constant exposure to pollen during spring and summer means the immune system remains on constant high alert, scanning the body for threats.
Scientists think this high level of immune surveillance may mean the body’s defences are able to snuff out fledgling cancer cells before they can get a foothold.
It’s well known that the immune system has the power to kill cancer cells; indeed, drugs that ramp up its response to tumour cells are at the forefront of modern immunotherapy cancer treatments.
Nobody is suggesting that those who experience hay fever should leave their symptoms untreated in order to potentially lower their risk of certain types of tumour, but the research could lead to new treatments, such as drugs that rev up immune cells that are extra-active in those with hay fever.
‘Harnessing the body’s immune system to fight cancer is already revolutionising treatment for patients,’ says Professor James Spicer, a drug development expert on Cancer Research UK’s New Agents Committee.
‘But studying the way people develop allergies could mean we can enlist a whole new family of immune cells to tackle cancer.’
Other researchers may have already identified one of the immune cells that could be enlisted to fight cancer.
A team at Tel Aviv University, in Israel, has shown that an immune cell called an eosinophil has anti-cancer properties.
Eosinophils are infection-fighting white blood cells thought to have evolved to fight parasitic infections. But they also have a destructive side and cause inflammation and swelling throughout the body during an allergic response — such as that seen in hay fever.
Professor Ariel Munitz, from Tel Aviv’s Sackler School of Medicine, says: ‘We wondered if, since eosinophils are capable of killing parasites, they might also be able to kill tumour cells.’
The professor’s team wanted to see if the eosinophils’ destructive power could be harnessed to fight cancer. They chose bowel cancer, since the digestive system is one of the places eosinophils readily populate once released from bone marrow, where they are made.
To begin with, they analysed bowel cancer samples from 275 patients and found the higher the number of eosinophils cancer cells contained, the less severe the tumour in terms of rate of growth. This suggested they were at least slowing tumour development.
In the second part of their research, scientists found that tumours in mice were destroyed when they were exposed to higher levels of eosinophils.
The researchers now hope to work with drug companies to develop a treatment that can direct eosinophils to kill tumours without triggering unwanted allergic reactions.