Many Patients With Cancer Lack Protection Against Measles, Mumps

A fourth of adult patients with cancer lacked antibodies to measles and almost 40% tested negative for mumps antibodies, according to a retrospective analysis of almost 1,000 patients.

Antibody-negative rates were higher among patients with hematologic malignancies and in younger adults, exceeding 50% for measles and mumps among patients younger than 60. Subgroup analyses showed similar age- and disease-related patterns of seroprevalence for both of the infectious diseases.

The results highlight cancer patients’ increased risk during outbreaks of measles and mumps and the need for community-based efforts to increase herd immunity to protect the vulnerable population, said Elizabeth M. Krantz, MS, of Fred Hutchinson Cancer Research Center in Seattle, and co-authors in JAMA Network Open.

“To our knowledge, this study is one of the first studies to measure measles and mumps seroprevalence among patients with cancer in the modern era of cancer treatment,” the authors stated. “These data suggest an increased risk for this patient population compared with the general population, in which approximately 8% lack protective antibodies to measles and 13% for mumps.”

“The highly contagious nature of measles and mumps, combined with the vulnerability of patients with cancer observed in this study, highlight the need to increase community immunity in the United States,” the researchers added. “Efforts to increase vaccine education across diverse populations and to improve vaccine policy and support of childhood vaccination can help protect those who either have limited benefit from or cannot receive MMR [measles, mumps, rubella] vaccination. In addition, findings from this study underscore the need for national standards that require MMR vaccination or documented seropositivity among healthcare practitioners who work with patients with cancer.”

Assessment of immune status is not routine for the general population of patients with cancer, particularly those with solid tumors, said Sonali Smith, MD, of the University of Chicago, who was not involved with the study.

“One of the interesting aspects of this study is that it is one of the larger analyses to show what the seroprevalence against measles and mumps is in patients with cancer at a point in time,” she told MedPage Today.

The potentially large number of patients without protective antibodies raises questions about how to protect the patient.

“In general, I would reimmunize, but I don’t think there are any guidelines,” said Smith, a clinical/scientific expert for the American Society of Clinical Oncology. “I’m sure some other physicians would try to reimmunize, but I think there is a bigger issue. As a country, we have eliminated mumps and measles through vaccine, but if [the protection] is beginning to fall, then we need to reinforce our herd immunity.”

Missing Data

Patients with cancer have an increased risk of infection-related complications. However, few studies have investigated the patients’ vulnerability to measles and mumps, Krantz and co-authors noted. Better understanding of measles and mumps immunity in patients with cancer has acquired new significance as a result of recent outbreaks and increased vaccine hesitancy nationwide.

Investigators sought to determine a point prevalence estimate for protective antibodies against measles and mumps in ambulatory patients with cancer. Toward that end, the team collected plasma samples from consecutive patients seen at Seattle Cancer Care Alliance/Fred Hutchinson during August 2019. Each sample was tested for measles and mumps immunoglobulin G (IgG) by means of a commercially available assay. The primary outcome was measles and mumps IgG seroprevalence, measured overall and among various subgroups.

The 959 patients included in the study had a mean age of 60, and men accounted for 510 of the total study population. A majority of the patients (60%) had solid tumors, and 146 of 383 patients with hematologic malignancies had a history of transplantation. The most common solid malignancies were gastrointestinal (16%), breast (13%), and genitourinary (11%); the authors did not describe the distribution of hematologic malignancies.

About a third of the patients had received some form of chemotherapy within the 30 days before plasma collection.

Variable Seroprevalence

The 75% overall antibody seroprevalence rate for measles included 63% for patients with hematologic malignancies and 83% for those with solid tumors. The lowest rates by tumor type were among patients who had a transplantation history (46%).

Seropositivity for measles varied considerably by age, ranging from 49% for patients ages 30 to 39 to 95% among patients 80 and over. In general, patients born before 1957 had higher seropositivity rates, presumably because they were older than 5 and eligible for the MMR vaccine when it was introduced in 1963, when measles and mumps infections were still common.

The 38% overall seroprevalence rate for mumps antibodies included 71% among patients with solid tumors, 48% in patients with hematologic malignancies, and 29% in the transplant subgroup. Similar to the age-related seroprevalence distribution pattern for measles, patients ages 30 to 59 had lower a lower prevalence rate (41%) as compared with rates ranging from 65% to 83% for older age groups.

Smith noted several study limitations, beginning with the lack of a cancer-free comparator group: “They have a lot of information about age, type of treatment, and a little bit less about the type of cancer, but I think what would have really strengthened the study is to know what is the relative seroprevalence in people who don’t have cancer,” she said.

The study also did not address the potential impact of intervention, such as reimmunization, Smith continued. The study population was overwhelmingly Caucasian, which limits generalizability to the U.S. population at large. Additionally, the investigators included all hematologic malignancies into a single category, even though blood cancers differ substantially, she said.