During October, Breast Cancer Awareness Month, it’s important to consider the dangers posed by contaminated food and water to women undergoing treatment for what is the second-most deadly cancer in U.S. women.  

Cancer patients receiving chemotherapy have suppressed immune systems, making them part of the 20 percent of the U.S. population at increased risk of foodborne or waterborne illness.  The outcome of exposure to dangerous pathogens depends on multiple factors, including the patient’s ability to elicit an immune response.

Chemotherapy treatments affect the body’s ability to detect pathogens and produce appropriate immune responses because the drugs used to stop neoplastic growth also kill immune cells.  

Cancer treatment has three main medical interventions: radiation therapy, chemothereapy and bone marrow transplants.  The first two treatments target rapidly dividing cells.  However, other cells in the body also divide quickly and these, too, are killed as collateral damage.

The three main types of immune cells, lymphocytes, macrophages, and neutrophils, are among those destroyed.  The destruction of these cells leads to a period of increased vulnerability to pathogens usually 1 to 2 weeks after treatment, and lasting 3 to 5 days.

Enteric pathogens take advantage of the weakened immune systems and “set up persistent and generalized infections.”  These infections can be far more severe and endure for far longer in immunocompromised patients than in the general population.

For example, the case-fatality rate for adenovirus infection in immunocompromised cancer patients is 53 percent, whereas those with healthy immune systems rarely succumb to the virus.

In order to combat this increased risk of infection, those preparing food for immunocompromised cancer patients must use great care.  The main areas of protection that can reduce the risk of infection are:  proper personal hygiene, cooking foods to kill pathogens and avoiding cross-contamination, avoiding high-risk food.  

Personal hygiene includes frequent hand washing and use of protective clothing, such as gloves and hair nets.  Attention to kitchen hygiene requires clean tools, cooking, and preparation surfaces.  These precautions reduce contamination of raw foods by the food handler.  Pathogens often spread by ill food handlers include Shigella spp., Hepatitis A, Norovirus, and other viral pathogens.

Pasteurization and proper cooking of foods is particularly important.  Raw dairy products should be avoided by cancer patients.  These are ideal mediums for many bacteria to live and grow, including E. coli O157:H7, Campylobacter jejuni, and Listeria monocytogenes.  

Raw and undercooked beef can contain E. coli O157:H7 and Toxoplasmosis gondii, a parasite that attacks the central nervous system.  Undercooked meats in general should be avoided.

Specific foods have especially high risks of being susceptible to contamination.  Shellfish from contaminated waters can contain Vibrio spp. and Norovirus.  If shellfish must be eaten by the patient, ensure they come from licensed and inspected vendor and are not from contaminated waters.  Alfalfa sprouts and other sprouted seeds also have a high risk of containing pathogens and should not be eaten.

Because  raw foods can contain any number of pathogens, it may be necessary for immunocompromised cancer patients to avoid all raw foods.  Cooked or canned vegetables and fruits can supplement the diet during these periods.

Foods known to contain Listeria monocytogenes, such as deli meats, hot dogs, soft cheeses, and raw dairy products, should not be given to cancer patients during periods of decreased immunity.  Cancer patients with solid tumors are from 66 to 229 times more susceptible to infection with L. monocytogenes.

These food-handling and consumption guidelines show the importance of providing nutritious foods to cancer patients while protecting them from unintentional exposure to food pathogens.  It is a sad fact that those most vulnerable in society often suffer disproportionately.  The young, elderly and immunocompromised are far more likely to become ill from pathogens found in the food they trusted to be safe to eat.

For more information see: 
Gerba, Charles, Joan Rose, Charles Haas. “Sensitive populations: who is at the greatest risk?” International Journal of Food Microbiology. 30(1996).
Medeiros, Lydia, Gang Chen, Patricia Kendall, Virginia Hillers. “Food Safety Issues for Cancer and Organ Transplant Patients.” Nutritional Clinical Care. 7.4 (2004).