Elsevier

Journal of Infection

Volume 72, Issue 6, June 2016, Pages 650-658
Journal of Infection

Infection-related hospitalizations in breast cancer patients: Risk and impact on prognosis

https://doi.org/10.1016/j.jinf.2016.04.003Get rights and content

Highlights

  • Infection-related hospitalizations are not uncommon in breast cancer patients.

  • Infection rates are highest within the first year of diagnosis.

  • Site-specific risks are most pronounced for sepsis and skin infections.

  • Patient, tumor and treatment characteristics define the infection risk profile.

  • Infection-related hospitalizations are an independent marker of poor prognosis.

Summary

Objectives

Infections are a common cause of hospitalization in breast cancer patients. We studied the risk, clinical characteristics and outcomes of infection-related hospitalizations in this patient population.

Methods

A Swedish registry-based study including 8338 breast cancer patients diagnosed between 2001 and 2008, followed prospectively for infection-related hospitalizations until 2010. Standardized incidence ratios (SIRs) were calculated using background rates from the general female population. Associations with clinical characteristics and mortality were analyzed using flexible parametric survival models.

Results

In total, 720 patients experienced an infection-related hospitalization during a median follow-up of 4.9 years. Infection rates were highest within the first year of diagnosis (SIR = 5.61, 95% CI; 4.98–6.32), and site-specific risks were most pronounced for sepsis (SIR = 3.14, 95% CI; 2.66–3.71) and skin infections (SIR = 2.80, 95% CI; 2.24–3.50). Older age at diagnosis, comorbidities, markers of tumor aggressiveness, chemotherapy and axillary node dissection were independent predictors of infectious disease risk. Infection-related hospitalizations were also independently associated with overall and breast cancer-specific death.

Conclusions

A significant number of breast cancer patients are hospitalized with an infection following diagnosis, which in turn predicts poor prognosis. The risk profile of infection-related hospitalizations is multifactorial, including patient, tumor and treatment-related factors.

Introduction

Breast cancer is the most common malignancy diagnosed in women worldwide and the number of prevalent cases is increasing due to the overall rise in breast cancer incidence and improved survival rate.1 As a result of the increased life expectancy, morbidity after a breast cancer diagnosis has become more important from a clinical and public health perspective.2 Infections are a common complication in breast cancer patients and result from immunosuppression due to treatment and the malignancy itself.3, 4 Most infections are transient in nature, but their consequences may last longer. Severe infections, for instance, have been associated with prolonged hospitalization and treatment delay,5, 6 and are a major cause of future morbidity and mortality.3, 7

Despite the considerable impact on patient outcome and health care use, limited data are available on the incidence of serious infections in breast cancer patients. Previous studies have primarily focused on infection-related hospitalizations during periods of chemotherapy-induced neutropenia8, 9 and data beyond the initial treatment period are scarce. Moreover, breast cancer and its treatment may predispose to infections at certain organ sites, but no studies to date have reported risk estimates for site-specific infections. Also, little is known about the tumor and treatment dependent risk profile and the impact of infection-related hospitalizations on mortality.

In the present study we aimed to assess the risk and prognostic implications of serious infections in breast cancer patients. Using registry-based data, we studied the incidence of infection-related hospitalizations in breast cancer patients as compared to the general female population, by time since diagnosis. We also examined associations with patient, tumor and treatment characteristics as well as the impact of infection-related hospitalizations on overall and breast cancer-specific survival.

Section snippets

Study population

The Stockholm Gotland Breast Cancer Register is a population-based clinical register recording all breast cancer diagnoses occurring in the Swedish counties of Stockholm and Gotland since 1976. The register has more than 95% completeness for women aged less than 75 years at diagnosis and contains detailed information on tumor characteristics and primary breast cancer treatment, as well as routine follow-up information on locoregional recurrence and distant metastasis.10, 11 For the present

Results

Descriptive characteristics of the breast cancer cohort are summarized in Table 1. Mean age at diagnosis was 57.4 years and the median length of follow-up was 4.9 years. In total, 720 patients experienced an infection-related hospitalization following diagnosis. When comparing rates of site-specific infections, respiratory infections and sepsis were most frequently reported. The largest group of other infections was unspecified and not classifiable according to organ site (Supplementary Table S2

Discussion

Infections are a common cause of hospitalization in breast cancer patients, but estimates of the actual risk and prognostic implications of infection-related hospitalizations are scarce. This is the first study reporting risk estimates by time since diagnosis and infection site. In total, 720 patients experienced an infection-related hospitalization during a median follow-up of 4.9 years. Infection rates were highest within the first year of diagnosis, and site-specific risks were most

Conflicts of interest

The authors declare no conflict of interest.

Author contributions

Study concept and design: JSB, EC, PH, KC.

Acquisition, analysis or interpretation of data: All authors.

Statistical analyses: JSB, ALVJ, MC.

Drafting of the manuscript: JSB, KC.

Critical revision and approval of the manuscript: All authors.

Acknowledgments

This work was financed by the Swedish Research Council (grant no: 2014-2271); the Swedish Cancer Society CAN (grant no: 2013-469) and FORTE (grant no: 2013-0474). The funders had no role in the study design; in the collection, analysis, and interpretation of the data; or the decision to submit the manuscript for publication. The study sponsors had no role in the design of the study, the collection, analysis or interpretation of the data, the writing of the manuscript or the decision to submit

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