title: Increased risk of active tuberculosis after cancer diagnosis.
abstract: Cancer may increase risk of active tuberculosis but evidence is sparse. We therefore examined tuberculosis risk in patients with incident cancer using Danish nationwide medical databases.
  
  
  
  We conducted a matched follow-up study comparing risk of active tuberculosis in cancer-exposed individuals to that in a general population comparison cohort, matched on gender, age, and country of origin, in different follow-up intervals using Cox regression.
  
  
  
  We identified 290,944 patients with incident cancer and 871,147 matched comparison cohort members during 1 January, 2004-30 November, 2013. After adjusting for comorbidities, the overall adjusted hazard ratio (aHR) for tuberculosis among cancer patients was 2.48 (95% confidence interval [CI]: 1.99-3.10). The highest tuberculosis risks were observed following cancers of the aerodigestive tract (aHR = 8.12; 95% CI: 4.33-15.22), tobacco-related cancers (aHR = 5.01; 95% CI: 3.37-7.44), and hematological cancers (aHR = 4.88; 95% CI: 2.27-10.48). Tuberculosis risk was highly elevated within the first year after cancer diagnosis (aHR = 4.14; 95% CI: 2.88-5.96), with a 6.78-fold increased aHR for cancer patients receiving cytostatics or radiotherapy. Beyond five years of observation, the overall aHR for tuberculosis remained at 2.66 (95% CI: 1.22-5.81).
  
  
  
  Cancer is a clinical predictor for increased risk of active tuberculosis, probably related to decreased infection barriers, immunosuppression, and shared risk factors.
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark. Electronic address: simonsendennis@gmail.com.
authors.forename: Dennis F
authors.initials: DF
authors.lastname: Simonsen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Dóra K
authors.initials: DK
authors.lastname: Farkas
authors.affiliation: Department of Epidemiology, Boston University School of Public Health, Boston, MA, USA.
authors.forename: Charles R
authors.initials: CR
authors.lastname: Horsburgh
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Reimar W
authors.initials: RW
authors.lastname: Thomsen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark; Department of Epidemiology, Boston University School of Public Health, Boston, MA, USA.
authors.forename: Henrik T
authors.initials: HT
authors.lastname: Sørensen
mesh_terms: D000293:Adolescent; D000305:Adrenal Cortex Hormones / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D015897:Comorbidity; D054697:Cytostatic Agents / Q000627:therapeutic use; D016208:Databases, Factual; D004198:Disease Susceptibility; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007165:Immunosuppression Therapy / Q000009:adverse effects; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000150:complications* / Q000175:diagnosis / Q000382:microbiology* / Q000628:therapy; D016016:Proportional Hazards Models; D012307:Risk Factors; D014376:Tuberculosis / Q000150:complications* / Q000453:epidemiology* / Q000382:microbiology; D055815:Young Adult
chemical_list: D000305:Adrenal Cortex Hormones; D054697:Cytostatic Agents
keywords: Cancer; Cohort study; Epidemiology; Immunosuppression; Tuberculosis