Key discovery about non-Hodgkin lymphoma

There is a surprise benefit to being either an only child, the oldest sibling or even enduring some allergies – you are significantly less likely to develop non-Hodgkin lymphoma (NHL), according to new research from the University of New South Wales (UNSW).

The key findings are that only children and eldest siblings are 50 percent less likely to develop NHL, while people with a history of food allergies have a 70 percent reduced risk. The presence of another allergic reaction, hay fever, indicates that a sufferer is 35 percent less likely to develop NHL. There is no protective effect for those with allergies to medicines.

“One of the reasons we did this study is because the incidence of NHL has been increasing rapidly over the past 20 to 30 years,” said the lead author of the report, UNSW Associate Professor Andrew Grulich from the National Centre in HIV Epidemiology and Clinical Research. “It is now the sixth most common cause of cancer death in Australia, yet we know very little about why people develop this disease.”

One of the things that is known about the disease is that immune deficiency is a strong risk factor for NHL, which arises from cells of the immune system. The investigators wanted to know whether other forms of immune dysregulation played a part.

“Allergies, or Atopy, are one type of immune disorder, but they have a protective effect,” said Professor Grulich. “In addition to allergy, I wanted to look at the effect of birth order of children because the ‘hygiene hypothesis’ clearly states that being a first-born child increases your risk of allergy.

“This seems to indicate that something important happens early in life – in the first year or so,” said Professor Grulich. “The reduction in NHL risk was very similar for both first-born and only children, and this points to something about being on your own for that first year or two.”

The paper Birth Order, Atopy, and Risk of Non-Hodgkin Lymphoma has just been published in the prestigious Journal of the National Cancer Institute.

The team carried out a population-based case-control study of NHL patients without immune deficiency in NSW and the ACT.

Researchers now hope that the finding will be confirmed by a proposed international collaborative study. If that study confirms these findings, laboratory research work would need to be conducted to find out why allergy and associated factors are associated with decreased NHL risk.