Chemotherapy kills fast growing cells and hence can be effective against cancer. But it does not discriminate between healthy and malignant cells. Hence, the trade-off for killing cancer cells is killing fast-growing, healthy cells as well.
The most serious side effect may be chemotherapy’s impact on the immune system. It drives down white and red blood cell counts as well as platelets. Low platelets can lead to unusual bleeding and low red blood cell counts can bring fatigue. Perhaps most important, low white blood cell counts leave us vulnerable to infectious agents we might normally resist and never even notice.
To counter this heightened susceptibility to infection, patients receiving chemotherapy must take various precautions to minimize their exposure to infection. Wearing masks, washing hands, limiting contacts, and even isolation rooms are just some of the precautions that patients routinely take.
As important as these practices are, they rest on the premise that infections arise from external sources. This was how I interpreted an E-coli infection I acquired several weeks after receiving induction chemotherapy for my leukemia. I blamed the hospital environment for my misfortune until my doctors offered an even more plausible explanation.
Much to my surprise, most of us have E-coli bacteria peacefully residing in our gut throughout our lifetimes. With a healthy immune system, these bacteria are well controlled and produce no troublesome symptoms. It is only when we are immunosuppressed that these bacteria can morph into major infections requiring aggressive, antibiotic treatment.
The same dynamic played out after my transplant. I was given anti-rejection medication to allow my transplanted stem cells to take root and construct a new immune system. This also caused immunosuppression and opened the door to another critter known as the cytomegalovirus. It is a common virus that resides in many of us but is usually well controlled by a healthy immune system. When that system is compromised by anti-rejection medication, the virus can break out and require proactive treatment with anti-viral medication.
My encounter with E-coli taught me to never scoff at adult diapers again. But more importantly, I learned that for all our well-intentioned efforts to minimize exposure to external agents of infection, sometimes we turn out to be our own worst enemy as “auto-infections” arise from deep within us.