It seems unlikely that chemotherapy and a dermatological condition such as shingles could be connected, however many patients who undergo chemo for treating cancer report the development of shingles or herpes zoster.
The chief explanation offered for contracting the infection seems to be the fact that the immune system is compromised or weakened due to the chemotherapy.
This is often true in the case of those who have had the chicken pox earlier in life who may have the virus lie dormant within the body and which comes alive so to speak during a time when the body’s natural defense mechanism or immune system has been compromised by chemo.
The coming alive of the virus at this time can result in the body getting the shingles infection. Chemo is essentially therapy that suppresses the immune system, thereby giving rise to infections such as shingles.
At some level it seems really unfair of life to firstly have someone suffer as grim a fate as cancer and then to add insult to injury, the patient develops shingles as well. The extreme pain of the infection, even the perceived ignominy of the condition can be difficult to take!