Acyclovir is an antiviral drug used to treat herpes simplex virus infections, shingles, and chickenpox [1]. However, its use in cancer patients is still a matter of debate. A study published in the Infectious Agents and Cancer journal suggests that acyclovir may have antitumor effects, particularly in patients with Epstein-Barr virus (EBV)-associated cancers [3]. The study found that acyclovir could inhibit the growth of EBV-infected cells in vitro and in vivo, and reduce the risk of developing EBV-associated cancers.

However, another study published in the National Center for Biotechnology Information suggests that acyclovir may not be suitable for all cancer patients [2]. The study found that acyclovir could cause serious side effects in immunocompromised patients, including those with cancer. These side effects include acute kidney injury, neurotoxicity, and hematologic abnormalities.

Therefore, cancer patients should consult with their doctors before taking acyclovir. Doctors can evaluate the patient's medical history and condition, and determine whether acyclovir is a suitable treatment option. Patients should also be aware of the potential side effects of acyclovir and report any adverse reactions to their doctors immediately.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/ACYCLOVIR
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7730702/
[3] https://infectagentscancer.biomedcentral.com/articles/10.1186/s13027-017-0128-7