Introduction/background: Neurodegeneration has in the last years been associated with a lower incidence of cancer, raising the question that there might be common mechanisms in the pathogenesis of both diseases, which can make patients with neurodegenerative diseases protected against cancer-development. This project thesis focuses on the subgroup polyglutamine diseases, and how this group of patients is affected by cancer. Method: This project thesis is a literature study that used the medical database PubMed to search for articles that were relevant for the issue of the thesis. The search words were “cancer AND polyglutamine diseases”, which gave 197 articles. Out of these, 8 articles were included in the thesis, and the rest were excluded based on title, abstract or full text. Results: The results showed that several studies had found a lower incidence of cancer among patients with either polyglutamine diseases in general or just one type of polyglutamine disease. Every study found a lower incidence of cancer in Huntington’s disease patients. One study that investigated the risk of cancer in patients with Huntington’s disease, hereditary ataxia and spinobulbar muscular atrophy, only found a reduced risk of cancer in HD and not in the other two groups. Discussion: All results support the theory that there might be protective mechanisms of cancer in patients with polyglutamine diseases. Whether this only applies to patients with HD or polyglutamine diseases in general is not completely understood. There are still only a few studies exploring this association, so more research is needed to make a proper conclusion.