Everolimus-associated cytomegalovirus colitis in a patient with metastasized breast cancer: a case report

Anti-cancer therapy put patients in an immunocompromised status. Reactivation of cytomegalovirus (CMV) in immunocompromised patient can cause a severe disease. Thus, we presented a case who had recurrent CMV colitis which complicate with rectovaginal fistula. We present a case of everolimus-associated cytomegalovirus colitis on a patient receiving everolimus and exemestane therapy for the treatment of metastasized breast cancer. The patient presented septic shock and acute peritonitis at first. Emergency exploratory laparotomy was performed. However, only edematous changes were observed over the terminal ileum, sigmoid colon and rectum. Four weeks after operation, we found feces coming out from her vagina. Colonoscopy was done and revealed rectovaginal fistula. Colonic and rectal mucosa moderate inflammation with multiple ulcer was also noted. Biopsy was done and the pathology proved CMV colitis. After treatment with ganciclovir, her symptoms improved. Everolimus was stopped for 12 weeks and was added back with a decreasing dose paradigm for breast cancer treatment. However, another episode of CMV colitis occurred again after resuming the everolimus. After anti-virus treatment, she was discharged. Due to adverse effects, everolimus therapy was discontinued. The standard treatment of hormone receptor positive and HER-2 negative metastatic breast cancer is everolimus together with exemestane. Due to the immunosuppressive effects of everolimus, the medication may cause invasive fungal infection or other opportunistic infections. Such infections are serious and may even be fatal. In this case, we did not consider CMV infection until rectovaginal fistula formation. Thus, for solid cancer patients presented with fever of unknown origin, clinicians should consider potential complications of CMV infection.