Approximately 48 million people, per year, are estimated to contract some form of foodborne disease[1], but foodborne infection is a risk which can be mitigated with appropriate food safety behaviors. [2]. Cancer patients experience a compromised immune system, both due to the mechanisms of cancer and due to the means by which treatments for cancer act upon the body[3]. This means that patients receiving treatment are at significantly higher risk of acquiring a foodborne infection than people living without cancer[4], and the Centers for Disease Control (CDC) has issued specialized guidelines for immunocompromised people [5]. Currently, approximately 5% of the US population are cancer survivors, with the raw number anticipated to increase from the current 16.9 million to 22.2 million, by 2030[6].
A person’s risk of developing foodborne disease depends on a number of factors related to the host, their environment, and the pathogen is question. In 1998, Coleman et al. posited the design of the Disease Triangle, a framework whereby microbial risk analysis could be performed by assessing the host, pathogen, and environment[7]; an updated version of this model, now called the Health Triangle, expands upon what, explicitly, might be controlled within each of these three categories[8]. Environmental factors include aspects such as diet, nutrition, exposure (i.e., through air, occupational exposure, and the indoor/outdoor environment). Host factors depend on the general host of the health, with factors such as age, genetics, immune system, and underlying illness being harder or even impossible to change. Coleman et al. add a third aspect to the Health Triangle, which includes the microbiota and modulators. Use of antibiotics, chemotherapy, fecal transplants, and pre-, pro-, and syn-biotics can all impact the microbiome, and some can be modulated with diet or treatment.
By performing appropriate food safety behaviors, cancer patients are able to decrease their risk of foodborne pathogen exposure. However, to be able to implement these behaviors, patients must, first, be aware of their increased risk and of the appropriate behaviors to take. In 2019, a cross-sectional survey study was performed, in which cancer patients receiving treatment were asked about their food safety knowledge, behaviors, attitudes, and risk perception. Nearly half of patients were unaware that they were at increased risk of foodborne infection (49.4%, n=139), and most participants reported consumption of high-risk foods (97.9%, n=276). Specific gaps were identified in food safety knowledge, particularly concerning appropriate food preparation, food acquisition, and cold storage.
Upon determining which knowledge areas fall short of recommendations, appropriate educational materials were designed and distributed. Using the results of the 2019 study, as well as information gathered by Evans et al., in a focus group centering the food safety educational preferences of patients and their caregivers[9], an educational module was crafted which specifically addressed gaps in the knowledge of cancer patients receiving treatment. The construction of the presentation was based on the Health Belief Model and viewing the intervention took approximately ten minutes. This module was tested for feasibility, accessibility, and efficacy by surveying patients for the targeted constructs immediately before, immediately after, and five weeks after participation in the intervention. Participant risk perception (p<0.001) significantly improved and was retained, and self-efficacy increased (p<0.001). Attitudes (p=0.025) improved initially but were not significantly different from baseline by follow-up (p=0.16). Knowledge scores improved from pre- to post-intervention (p<0.001), but follow-up scores were not significantly different from either post-intervention (p=0.397) or from baseline (p=0.549). Intent to implement appropriate food behaviors, at post-intervention, was significant (p<0.001) but there were no significant differences in reported behaviors between baseline and follow-up (p=0.987).
The microbiome is an important facet of the Health Triangle, both for its ability to impact the immune system[10], as well as its reciprocal relationship with diet[11–13]. Using mice as a model system, a study was performed to assess how diet composition, disease progress, and toxin exposure impact the microbiome during cancer. Mice were divided into dietary and treatment cohorts, wherein they received one of four diets (high omega-3, low sucrose; high omega-3, high sucrose; low omega-3, low sucrose; low omega-3, high sucrose) and either chemotherapy treatment or a saline vehicle. Fecal samples were taken at pre-determined timepoints, in the experiment, to determine baseline, effects of diet, cancer onset, surgical treatment, and cancer treatment. Microbial DNA was isolated from samples and amplicon sequence variants (ASVs) were analyzed to assess changes in the microbiome population. Richness significantly decreased over time (p< 0.001), Akkermansia muciniphila was negatively correlated with overall richness (r(64) = -0.55, p = 3e-08), and alpha-diversity and abundance were impacted by diet, treatment, disease progression, and associated interactions.
These three chapters provide a more holistic view of how food safety and the microbiome are important factors in achieving positive cancer treatment outcomes.