Cancer in machado joseph disease patients – low frequency as a cause of death

Publication date: Available online 30 March 2017
Source:Cancer Genetics
Author(s): Gabriele Nunes Souza, Nathália Kersting, Thomaz Abramsson Gonçalves, Daphne Louise Oliveira Pacheco, Maria-Luiza Saraiva-Pereira, Suzi Alves Camey, Jonas Alex Morales Saute, Laura Bannach Jardim
BackgroundSince polyglutamine diseases have been related to a reduced risk of cancer, we aimed to study the 15 years cumulative incidence of cancer (CIC) (arm 1) and the proportion of cancer as a cause of death (arm 2) in symptomatic carriers of spinocerebellar ataxia type 3/Machado Joseph disease (SCA3/MJD).MethodsSCA3/MJD and control individuals from our state were invited to participate. A structured interview was performed. CIC as published by the Brazilian National Institute of Cancer, was used as populational control. Causes of death were obtained from the Public Information System on Mortality.ResultsWe interviewed 154 SCA3/MJD patients and 80 unrelated controls: CIC was 7/154 (4.5%) and 5/80 (6.3%), respectively. The interim analysis for futility showed that the number of individuals required to detect a significant difference between groups (1,938) would be three times larger than the existing local SCA3/MJD population (625), for an absolute risk reduction of 1.8%. Then this study arm was discontinued due to lack of power. In the same period, cancer was a cause of death in 9/101 (8.9%) SCA3/MJD and in 52/202 (26.2%) controls, with an absolute reduction risk of 17.3% (OR 0.27, 95%CI 0.13 to 0.58, p=0.01).DiscussionA significant reduction of cancer as cause of death was observed in SCA3/MJD, suggesting a common effect to all polyglutamine diseases.



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