By Dr Ananya Mandal, MD
Those suffering from Huntington's disease, a debilitating brain condition, seem to have a “protection” from cancer, according to a study in Sweden.
Dr Jianguang Ji, Lund University, and Skåne University Hospital, Malmö, Sweden, and colleagues investigated data from the Swedish Cancer Registry. Researchers analyzed Swedish hospital data from 1969 to 2008. They found 1,510 patients with Huntington's disease. During the study period, 91 of those patients subsequently developed cancer. The authors said that was 53% lower than the levels expected for the general population.
Researchers describe identifying 1,510 patients with Huntington’s disease (HD) and other PolyQ conditions: spinobulbar muscular atrophy (SBMA), dentatorubral and pallidoluysian atrophy, and six types of spinocerebellar ataxia. All patients with polyglutamine diseases or polyQ diseases present with progressive degeneration of a population of neurons in the central nervous system that are involved in motor control.
Cancer was diagnosed in 91 HD patients (6%), 34 SBMA patients (7%), and 421 HA patients (12%). The chances of being diagnosed with cancer were 53% lower in HD patients, 35% lower in SBMA patients, and 23% lower in HA patients compared with the general population.
The authors said, “We found that the incidence of cancer was significantly lower among patients with polyglutamine diseases than in the general population. The mechanisms behind the protective effects against cancer are unclear and further research is warranted.” Before diagnosis of a polyQ disease, the risk of cancer was even lower. Cancer risk in the unaffected parents of patients with polyQ diseases was similar to that in the general population. PolyQ diseases belong to a group of rare neurodegenerative disorders that are characterized by the expansion of certain amino acid sequence repeats (Cystosine-Adenine-Guanine or CAG) in specific genes.
Dr Jianguang Ji, from the Center for Primary Health Care Research at Lund University, told the BBC, “Clarification of the mechanism underlying the link between polyglutamine diseases and cancer in the future could lead to the development of new treatment options for cancer.” The authors conclude, “Our findings suggest a common mechanism in patients with polyQ diseases that protects against the development of cancer, and expansion of the polyglutamine tracts seems likely… Future studies should investigate the specific biological mechanisms underlying the reduced cancer risk in patients with polyQ diseases.”
Eleanor Barrie, senior science information officer at Cancer Research UK, said, “These are interesting results. It's not clear how the genetic changes that cause Huntington's and other similar diseases could protect against cancer, and research in the lab will help to find out more. Scientists at Cancer Research UK and around the world are probing the genetic faults that contribute to cancer in their quest to beat the disease, and this is another potential avenue to explore.”