Chronic fatigue syndrome and subsequent risk of cancer among elderly US adults
– Source: Cancer, May 30, 2012
by Cindy M Chang, Joan L Warren, Eric A Engels
[Note: an OR (odds ratio) of 1.0 would signify no difference in average risk between CFS & non-CFS populations. An OR of 1.88, for example, would indicate an 88% greater average risk for the CFS population. OR of 1.51 would be 51% greater average risk, and so on.]
Summary: Using US linked registry data on 1.2 million cancer cases and 100,000 population-based controls, risk was evaluated for a wide range of cancer types following a diagnosis of chronic fatigue syndrome. A strongly significant elevated risk was found for non-Hodgkin lymphoma associated with chronic fatigue syndrome, and in particular, associations for 2 specified non-Hodgkin lymphoma subtypes (diffuse large B cell lymphoma and marginal zone lymphoma).
Background: The cause of chronic fatigue syndrome (CFS) is unknown but is thought to be associated with immune abnormalities or infection.
Because cancer can arise from similar conditions, associations between CFS and cancer were examined in a population-based case-control study among the US elderly.
Methods: Using linked Surveillance, Epidemiology, and End Results (SEER)-Medicare registry data, approximately 1.2 million cancer cases and 100,000 controls (age range, 66-99 years; 1992-2005) were evaluated.
CFS was identified in the period more than 1 year prior to selection, using linked Medicare claims. Unconditional logistic regression was used to estimate the odds ratios (ORs) comparing the CFS prevalence in cases and controls, adjusting for age, sex, and selection year. All statistical tests were 2-sided.
• CFS was present in 0.5% of cancer cases overall and 0.5% of controls [1 in 200 people in Medicare database].
• CFS was associated with an increased risk of non-Hodgkin lymphoma (NHL) (OR = 1.29, 95% confidence interval [CI] = 1.16-1.43, P = 1.7 × 10?6th).
• Among non-Hodgkin lymphoma subtypes, CFS was associated with diffuse large B cell lymphoma (OR = 1.34, 95% CI = 1.12-1.61), marginal zone lymphoma (OR = 1.88, 95% CI = 1.38-2.57), and B cell NHL not otherwise specified (OR = 1.51, 95% CI = 1.03-2.23).
CFS associations with non-Hodgkin lymphoma overall and NHL subtypes remained elevated after excluding patients with medical conditions related to CFS or non-Hodgkin lymphoma, such as autoimmune conditions.
CFS was also associated, although not after multiple comparison adjustment, with cancers of the pancreas (OR = 1.25, 95% CI = 1.07-1.47), kidney (OR = 1.27, 95% CI = 1.07-1.49), breast (OR = 0.85, 95% CI = 0.74-0.98), and oral cavity and pharynx (OR = 0.70, 95% CI = 0.49-1.00).
Conclusions: Chronic immune activation or an infection associated with CFS may play a role in explaining the increased risk of non-Hodgkin lymphoma.
Source: Cancer, May 30, 2012. DOI: 10.1002/cncr.27612, by Chang CM, Warren JL, Engels EA. Division of Cancer Epidemiology and Genetics, National Cancer Institute, Rockville, Maryland; Division of Cancer Control and Population Sciences, National Cancer Institute, Rockville, Maryland, USA. [Email: Eric A. Engels MD, MPH (firstname.lastname@example.org)] National Cancer Institute Senior Investigator Eric Engels, MD, MPH, specializes in study of immunosuppression, infection and inflammation in cancer; Cindy Chang, PhD, MPH, specializes in non-Hodgkin lymphoma research; and Joan L Warren, PhD, specializes in Medicare data analysis for cancer-related research.
The authors note: This study used the linked Surveillance, Epidemiology, and End Results (SEER)-Medicare database. The interpretation and reporting of these data are the sole responsibility of the authors. The authors acknowledge the efforts of the Applied Research Program, National Cancer Institute; the Office of Research, Development, and Information, Centers for Medicare and Medicaid Services; Information Management Services, Inc.; and the SEER Program tumor registries in the creation of the SEER-Medicare database. We thank Winnie Ricker (Information Management Services, Rockville, MD) for assistance with database management.