Study strengthens link between smoking and Hodgkin’s disease

Latest research has shown that people who smoke are almost twice as likely to develop Hodgkin’s Disease, a type of cancer that strikes a component of the body’s immune defenses. The amount that people smoke and how long they have maintained the habit is also a factor according to Dr Nathaniel Briggs of Meharry Medical College in Nashville, Tennessee and colleagues.

‘Overall, men who were current smokers had a significant, nearly twofold increase in risk of Hodgkin’s disease, with risk increasing linearly with increasing years of smoking and number of packs-per-day of cigarettes smoked,’ Briggs said.

Researchers stated however that quitting the habit makes a difference. ‘The good news is that, among former smokers, the risk of Hodgkin’s disease decreased linearly with increasing time since cessation of smoking,’ Briggs said.

Previous research has investigated whether cigarette smoke increases the risk of this type of cancer, but studies have produced mixed results. Briggs attributed this to the fact that the study was relatively small and there was not a clear distinction between past and present smokers.

In this current study, Briggs and his colleagues collected detailed information on the smoking histories of 343 men between the ages of 32 and 60 with Hodgkin’s disease and almost 2,000 others who were free from cancer. The disease-free men were discovered by randomly dialing telephone numbers until the investigators were able to match people of the same age and background to the Hodgkin’s patients.

During interviews, the authors classified men as smokers if they said they had ever smoked at least a half a packet of cigarettes per week for at least a year during their lives. Current smokers were those who said they had smoked within two years before the interviews. Smokers provided information about how much they smoked, when they started, and, if and when they had quit.

Briggs and his team discovered that current smokers were almost twice as likely as people who had never smoked to develop Hodgkin’s disease. In people who smoked at least two packets each day or had maintained the habit for at least 30 years, the risk rose to 2.5 times that of someone who had never smoked.

However, people who had stopped smoking at least 10 years before had a lower risk of the cancer than both current smokers and those who had kicked the habit more recently.

The link between smoking and Hodgkin’s appeared strongest for one type of the disease, known as mixed cellularity, the most aggressive and common form diagnosed in patients 50 years or older. ‘Men who currently smoked two or more packs-per-day of cigarettes had a significant, greater than sevenfold increase in risk for mixed cellularity Hodgkin’s disease,’ Briggs said.

Although the means by which cigarettes could increase the risk of the cancer remain unknown, Briggs noted that certain ingredients of tobacco and cigarette smoke have been implicated as risk factors for Hodgkin’s. Alternatively, he suggested that smoking could also decrease the functioning of certain immune system cells, indirectly leading to the cancer.

Briggs’ report has been published in the American Journal of Epidemiology. For more information of Hodgkin’s disease, go the Haematology Suite of Virtual Cancer Centre.

(Source: ASCO)