Increased risk of incident primary cancer after Staphylococcus aureus bacteremia: A matched cohort study.

Susceptibility to infectious disease may be a marker of immunodeficiency caused by unrecognized cancer. To test the hypothesis, the risk of incident primary cancer was estimated among survivors of Staphylococcus aureus bacteremia (SAB) and compared to a random population cohort.Nation-wide population-based matched cohort study. Cases of SAB were identified from a national database and incident primary cancers were ascertained by record linkage. Incidence rate (IR) and ratio (IRR) with 95% confidence interval (CI) of 27 cancers was calculated by Poisson regression.During the first year of follow-up, 165 and 943 incident cases of cancer occurred in the case cohort (n = 12,918 (1.3%)) and the population cohort (n = 117,465 (0.8%)) for an IR of 3.78 (3.22-4.40) and 2.28 (2.14-2.43) per 100,000 person-years. The IRR was 1.65 (1.40-1.95). Of 27 cancers, 7 cancers occurred more frequently amongst cases than controls: cervical cancer (IRR 37.83 (4.23-338.47)), multiple myeloma (IRR 6.31 (2.58-15.44)), leukemia (IRR 4.73 (2.21-10.10)), sarcoma (IRR 4.73 (1.18-18.91)), liver cancer (IRR 3.64 (1.30-10.21)), pancreatic cancer (IRR 2.8 (1.27-6.16)), and urinary tract cancer (IRR 2.58 (1.23-5.39)). Compared to the control population, the risk of cancer was higher for those without comorbidity and with younger age. The overall risk of cancer during 2 to 5 years of follow-up was not increased (IRR 0.99 (95% CI: 0.89-1.11). However, the risk of pharyngeal cancer was increased (IRR 1.88 (1.04-3.39)) and the risk of liver cancer remained increased (IRR 3.93 (2.36-6.55)).The risk of primary incident cancer was 65% higher in the SAB cohort compared to the population cohort during the first year of follow-up and included 7 specific cancers. The risk was higher for those without comorbidity and with younger age. Screening for these specific cancers in selected populations may allow for earlier detection.

Prevalence and clinical significance of neutropenia discovered in routine complete blood cell counts: a longitudinal study.

BACKGROUND: Neutropenia, defined as an absolute blood neutrophil count (ANC) <1.5 G L(-1) , may accompany a variety of diseases. However, the clinical significance of neutropenia detected in a routine complete blood cell count is poorly understood. METHODS: Using a primary care resource, comprising more than 370 000 individuals, we assessed the association with a number of previously recognized conditions as well as all-cause mortality in the 4 years following the identification of neutropenia. By matching laboratory data with Danish nationwide health registers, risk estimates were assessed. RESULTS: Neutropenia was observed in approximately 1% of all individuals and was associated dose dependently with viral infections, haematological malignancies (but not autoimmune disorders or solid cancers) and mortality. Neutropenia was particularly associated with HIV, acute leukaemias and myelodysplastic syndromes. Odds ratios [95% confidence interval (CI)] for viral infections were 2.32 (1.84-2.91), 2.80 (2.20-3.57) and 4.77 (3.22-7.07) for subnormal (≥1.5-1.8 G L(-1) ), mild (≥1.0-1.5 G L(-1) ) and moderate-severe (≥0.0-1.0 G L(-1) ) neutropenic individuals, respectively (all P < 0.001). Likewise, odds ratios (95% CI) for haematological malignancies were 3.23 (2.35-4.45), 8.69 (6.58-11.47) and 46.03 (33.98-62.35 ), for the same neutropenia levels, respectively (all P < 0.001). Thus, the lower the ANC, the greater the likelihood of these diseases. The relative risk estimates observed for severe neutropenia corresponded to absolute risks of haematological malignancies and mortality from any cause of 40% and >50%, respectively. CONCLUSIONS: Neutropenia is an ominous sign necessitating careful follow-up. The risk estimates presented here support focusing attention to viral diseases and haematological malignancies when neutropenia is observed.