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Your Good Health: Cause behind case of CMML seems to be unknown

About 6% to 10% of chronic myelomonocytic leukemia cases are related to chemotherapy or radiation.
Dr. Keith Roach

Dear Dr. Roach: My husband recently died one week after his 80th birthday. According to his death certificate, he died of lung cancer (not a surprise) and chronic myelomonocytic leukemia (CMML), which was a total surprise. He was always a healthy and vital man.

He had his first-ever surgical procedure in 2020 and got the lower lobe of his right lung removed. Over the years, he would develop small tumours in both lungs. He received very aggressive chemotherapy in 2020. He was then given Keytruda for two years and developed an irregular heartbeat.

Then his bloodwork was so irregular that he could not have Keytruda sometimes. Could Keytruda have been responsible for those blood tests, the irregular heartbeat, and the CMML? Our son died at the age of five of aplastic anemia, and my father-in-law died in 1963 of leukemia. (But his death certificate also said “aplastic anemia.”)

I’m thinking my husband’s genetics were his downfall because of the CMML and the aplastic anemia. Can you explain how all of this happened?


I am sorry to hear about your husband, and I will try to help make some sense of it.

CMML, a type of blood cancer, is not thought to be an inherited disorder, so it isn’t a genetic issue. However, about 6% to 10% of CMML cases are related to chemotherapy or radiation, so this could be possible. Keytruda is a type of immunotherapy called a checkpoint inhibitor. Cancer cells can block the immune system cells (specifically T-cells) from doing their job of destroying cancers, so Keytruda blocks the ability of cancer cells to do this. Even so, it has significant toxicities.

An irregular heartbeat is reported in 4% to 11% of recipients. It may also cause anemia, but this happens less often than with chemotherapy. Keytruda often causes abnormalities in many blood tests, particularly those related to kidney, liver and endocrine-gland function. Despite all of our advances, medication for cancer still has the potential to hurt the body.

As far as the CMML, there are case reports of blood cancers following checkpoint inhibitors, but I couldn’t find any of Keytruda being associated with CMML; in fact, Keytruda is being studied as a treatment for CMML. It’s possible your husband’s blood cancer is related to the initial chemotherapy. Still, the average time from chemotherapy to the development of CMML is five to seven years, so it’s unlikely to be related.

Dr. Roach Writes: A recent column on quinolone drugs, such as levofloxacin (Levaquin) and ciprofloxacin (Cipro), generated strong emotions from people who had complications from this treatment. Most people said they were never told about the potential for harm from the meds, but some reported that they were given warnings. My major point here is to highlight the dangers of antibiotic use and hopefully decrease the unnecessary use of quinolone drugs.

One reader who has taken multiple courses of levofloxacin without problems asked whether they are less likely to develop tendinopathy. I couldn’t find an answer in the literature. However, since the antibiotic gets into and damages the tendons, it is more probable that a person has an increased susceptibility to tendon damage after multiple courses.

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