There have been reports of increased cancer risk in patients with Myotonic Dystrophy. another study was just published highlighting the risk of cancer in this disease. The conclusion of the study was 

Conclusion: There is an increased risk of death, and probably cancer, in relatives with DM1 and in those whose DM1 status is unknown. This suggests a
need to perform a careful history and physical examination, supplemented by
genetic testing, to identify family members at risk for DM1 and who might
benefit from disease-specific clinical care and surveillance.