Zoster risk elevated before and after haematological cancer diagnosis
Older adults who are diagnosed with cancer appear to have an elevated risk of developing zoster, particularly those diagnosed with haematological cancers, according to findings of an Australian study.
“[W]e found that a diagnosis of cancer was associated with about a 40 percent higher risk of developing zoster compared [with] those without cancer [with a] substantially greater [risk] among those with haematological cancers compared [with] those with solid organ cancers,” said the researchers.
The risk of zoster was higher among patients with cancer compared with those without (adjusted hazard ratio [adjHR], 1.41, 95 percent confidence interval [CI], 1.32–1.52), with a higher risk among those with haematological cancers (adjHR, 3.74, 95 percent CI, 3.11–4.51) than those with solid cancers (adjHR, 1.30, 95 percent CI, 1.21–1.40; pheterogeneity<0.001). [J Infect Dis 2018;doi:10.1093/infdis/jiy625]
Among those who developed haematological cancers, the risk for zoster was elevated 1–2 years prior to their cancer diagnosis compared with those who had not developed cancer by end of follow up (adjHR, 2.01, 95 percent CI, 1.31–3.09), though this elevated risk did not extend to individuals who developed solid cancers (adjHR, 0.90, 95 percent CI, 0.75–1.07).
The risk of zoster was particularly elevated within the first year after cancer diagnosis (adjHR, 5.09, 95 percent CI, 3.83–6.75 for haematological cancer and adjHR, 1.44, 95 percent CI, 1.26–1.64 for solid cancer), with the risk reducing over time. Three years after cancer diagnosis, the risk of zoster remained elevated among patients with haematological cancers (adjHR, 2.13, 95 percent CI, 1.37–3.30), though the risk among those with solid cancers was akin to those without cancer.
Compared with patients without cancer, the risk of zoster among patients with solid cancers who were treated with chemotherapy was higher (adjHR, 1.83, 95 percent CI, 1.60–2.09) than those who did not receive chemotherapy (adjHR, 1.16, 95 percent CI, 1.06–1.26; pheterogeneity<0.001). The risk of zoster was also elevated among patients with solid cancers who received radiotherapy only (adjHR, 1.38, 95 percent CI, 1.17–1.63) but not among those who did not receive chemo- or radiotherapy (adjHR, 1.10, 95 percent CI, 0.99–1.21).
The results were based on a prospective cohort study of 241,497 adults from New South Wales, Australia (mean age at baseline 62 years, 54.5 percent female) who were followed up for 1,760,481 person-years, during which time, a total of 20,286 new cancer cases and 16,350 first zoster cases were diagnosed.
Unlike those with solid cancers in whom the increased zoster risk appeared to be driven by chemotherapy treatment, the elevated risk pre-haematological cancer diagnosis points to a potential role played by “immune dysfunction from the haematological cancer” in activating the zoster infection, with cancer treatment increasing the risk as evidenced by the continued elevated risk post-diagnosis, said the researchers.
The findings also call attention to the role of zoster vaccination in patients with cancer, they added. “Clinical guidelines recommend antivirals for zoster prevention in patients with haematological cancer receiving specific chemotherapies; [J Natl Compr Canc Netw 2016;14:882-913] however, they are less clear for solid organ cancer patients receiving conventional chemotherapy.”
With newly developed zoster vaccines demonstrating safety and immunogenicity in patients with HIV and those who have undergone haematopoietic stem cell transplantation, [J Infect Dis 2015;211:1279-1287; Blood 2014;124:2921-2929] “zoster vaccination now holds promise as a preventive strategy considered for cancer patients, particularly those expected to receive chemotherapy,” they said.