Investigating the effects of olanzapine on appetite and weight in patients with cancer in a systematic review.

PURPOSE: Anorexia, malnutrition, and cachexia are common in patients with cancer, yet evidence-based pharmacological guidance remains limited. Olanzapine is an antipsychotic that can increase appetite and cause weight gain. This systematic review evaluated the effects of olanzapine on appetite and body weight in patients with cancer.

METHODS

This systematic review included randomized controlled trials (RCTs) and observational studies assessing the effects of olanzapine on appetite and/or body weight in patients with cancer. The search strategy was conducted in Medline (PubMed), Embase, and the Cochrane Library. Risk of bias was assessed using Cochrane RoB2 for RCTs and the ROBINS-I for observational studies.

RESULTS

Of 1,733 records identified, 79 reports underwent full-text review. Fourteen RCTs, one prospective observational study, and three retrospective studies met the inclusion criteria. Most studies were not designed primarily to evaluate olanzapine as an orexigenic intervention; instead, olanzapine was typically studied for other indications (e.g. chemotherapy-induced nausea and vomiting control), with appetite and/or weight reported as secondary outcomes. Weight gain with olanzapine was reported in two RCTs using 2.5-5 mg/day for 8-12 weeks in adults. Increased appetite was reported in 10 of 14 studies in which olanzapine (2.5-10 mg/day) was administered for 3 days to 12 weeks. However, only three studies prospectively assessed appetite as a primary outcome, and only two prespecified body weight change as an endpoint, indicating that most evidence derives from secondary analyses. Most RCTs raised some concerns or were at high risk of bias, and observational studies generally had serious or critical risk of bias for outcomes of interest. Only 2 RCTs were judged to be at low risk of bias, underscoring substantial methodological limitations and heterogeneity in populations, indications, dosing regimens, and outcome definitions.

CONCLUSIONS

Available evidence suggests that olanzapine may have orexigenic effects in patients with cancer, with increased appetite reported in several studies and body weight gain observed with long-term use. These findings should be interpreted cautiously given the heterogeneity in study designs and the generally limited methodological quality of the evidence. Further research is needed to confirm these effects and to define the optimal dose and treatment duration for improving appetite and body weight in patients with cancer.