Significantly lower incidence of cancer among patients with Huntington disease: An apoptotic effect of an expanded polyglutamine tract?

BACKGROUND: The authors of this study have previously observed that cancer is rarely reported on the death certificates of patients with Huntington disease. This study was undertaken to investigate whether this disorder is associated with a lower incidence of cancer.

METHODS: A total of 694 patients with Huntington disease who had survived at least to age 45 years during the period 1943-1993, and 695 individuals at risk and at least age 55 years during the same period, were selected from the Danish Huntington Disease Registry. The occurrence of cancer was determined from the files of the Danish Cancer Registry and compared with national incidence rates for various categories of tumors.

RESULTS: The overall incidence of cancer was significantly lower among patients with Huntington disease, but not among their healthy relatives. The standardized incidence ratio for the Huntington patients was 0.6 with a 95% confidence interval of 0.5-0.8. The lower incidence was seen for cancers of all major tissues and organs except the buccal cavity and the pharynx.

CONCLUSIONS: The lower incidence of cancer among patients with Huntington disease seems to be related to intrinsic biologic factors. One explanation may be that the modified protein, huntingtin, encountered in Huntington disease protects against cancer by inducing or increasing the rate of naturally occurring programmed cell death in preneoplastic cells.