Feasibility of myelosuppressive chemotherapy in psychiatric patients on clozapine: A systematic review of the literature

Abstract

Objective Clozapine is the favoured antipsychotic for treatment‐refractory schizophrenia, but has a 1%‐2% incidence of agranulocytosis. Patients who require chemotherapy therefore pose a unique management dilemma for haematologists, oncologists and psychiatrists. Methods The Ovid MEDLINE and EMBASE databases were searched to identify reports describing use of clozapine concurrent with chemotherapy until 31 March 2019. The following terms (with variations) were used: neoplasm, cancer, tumour, malignancy, chemotherapy, antineoplastic and clozapine. Results Twenty‐seven cases were included after reviewing titles and abstracts for relevance. Fifteen patients had solid organ tumours, and 12 had haematological malignancies, including three who underwent autologous haematopoietic stem cell transplantation (AutoHSCT). Clozapine was continued in 14 cases (albeit dose reduced in 2), with a reported median neutropaenic nadir of 0.29 × 109/L (range 2.2 to <0.0 × 109/L). Clozapine was discontinued or substituted for another antipsychotic in the remaining 13 cases, all except one of whom experienced marked psychiatric deterioration. The only neutropenia‐related complication was one case of bacteraemia with high‐dose melphalan conditioning for AutoHSCT. Conclusions These findings argue in favour of clozapine continuation during chemotherapy. Further research is needed to develop guidance to minimise the risk of neutropenia‐related complications from concurrent treatment.

Hodgkin Lymphoma in Patients Receiving Clozapine Treatment

“…Discontinuation of clozapine carries a significant risk of psychiatric relapse that may affect compliance with chemotherapy and therefore should be weighed against the risk of harm from the potential clozapine-induced neutropenia. On the other hand, the risk of clozapine-induced agranulocytosis may make it difficult to distinguish the cause of neutropenia during cancer chemotherapy 4 . The ABVD regimen is reported to be associated with neutropenia in 15% to 39% of patients and severe infections occur in only 2% to 8% of patients 5 …”

The Risk of Antipsychotic Drugs on Breast Cancer: A Systematic Review and Meta-analysis

“… 29 However, others such as clozapine in conjunction with chemotherapy might increase cancer-related complications such as neutropenia. 30 …”

Clozapine and chemotherapy: a dangerous couple or a necessary partnership?

“…Others have also had success with using G-CSF in chemotherapy patients,8 including those with B-cell lymphoma 9. Grainger et al 10 conducted a literature review into similar cases and recommended that clozapine should be continued during chemotherapy for patients already established on clozapine treatment. They describe how, in almost all of the patients in whom clozapine was discontinued, there was a deterioration in the psychiatric symptom of the patients.…”