Patients with myotonic muscular dystrophy (MMD) - a form of muscular dystrophy are at an increased risk of cancer, reveals study published in the December 14 issue of JAMA.
Case reports have suggested that patients with MMD may be at increased risk of benign and malignant tumors, according to background information in the article.
Shahinaz M. Gadalla, M.D., Ph.D., of the National Cancer Institute, National Institutes of Health, Bethesda, Md., and colleagues conducted a study to evaluate the risk of cancer for patients with MMD. The researchers identified 1,658 patients with an MMD discharge diagnosis in the Swedish Hospital Discharge Register or Danish National Patient Registry between 1977 and 2008. These patients were linked to their corresponding cancer registry. In both countries, approximately half of the patients were men, 40 percent died during follow-up, and 6 percent developed cancer. Patients were followed up from date of first MMD-related inpatient or outpatient contact to first cancer diagnosis, death, emigration, or completion of cancer registration.
During follow-up, 104 patients with a diagnosis of MMD developed cancer, compared with what would be 52 expected cases (from cancer rates of the general population). The researchers found that MMD patients did have an increased overall cancer risk. "Most notably, we observed significant excesses of endometrial cancer, brain cancer, ovarian cancer, and colon cancer. Our data also suggested possible excesses of eye cancer, other female genital organ cancer, thyroid cancer, and pancreatic cancer. Close similarity in overall and site-specific cancer excess was observed in both Swedish and Danish MMD patients," the authors write.
No statistically significant sex difference was observed in overall cancer risk between women and men after excluding genital organ cancers. In age-stratified analyses (less than 50 vs. 50 years of age or older), there was also no statistically significant difference in overall cancer risk.
"Our findings have implications for the clinical management of MMD patients, including at a minimum the implementation of appropriate validated routine population-based cancer screening strategies, particularly for colon cancer, and careful assessment of therapy-related risks and benefits. The incidence rates for a number of the excess cancers are relatively low, despite their large relative risks. Screening for these uncommon cancers should not be implemented in the absence of demonstrated clinical utility," the researchers conclude.