Anorexia occurs in 30%-80% of patients with advanced malignancies, which may be worsened with chemotherapy. This trial assessed the efficacy of olanzapine in stimulating appetite and improving weight gain in patients receiving chemotherapy.

Adults (≥18 years) with untreated, locally advanced, or metastatic gastric, hepatopancreaticobiliary (HPB), and lung cancers were randomly assigned (double-blind) to receive olanzapine (2.5 mg once a day for 12 weeks) or placebo along with chemotherapy. Both groups received standard nutritional assessment and dietary advice. The primary outcomes were the proportion of patients with weight gain > 5% and the improvement in appetite (assessed by the visual analog scale [VAS] and the Functional Assessment of Chronic Illness Therapy system of Quality-of-Life questionnaires Anorexia Cachexia subscale [FAACT ACS]). Secondary end points were change in nutritional status, quality of life (QOL), and chemotherapy toxicity.

We enrolled 124 patients (olanzapine, 63 and placebo, 61) with a median age of 55 years (18-78 years), of whom 112 (olanzapine, 58 and placebo, 54) were analyzable. The majority (n = 99, 80%) had metastatic cancer (gastric [n = 68, 55%] > lung [n = 43, 35%] > HPB [n = 13, 10%]). The olanzapine arm had a greater proportion of patients with a weight gain of > 5% (35 of 58 [60%] 5 of 54 [9%], < .001) and improvement in appetite by VAS (25 of 58 [43%] 7 of 54 [13%], < .001) and by FAACT ACS (scores ≥37:13 of 58 [22%] 2 of 54 [4%], = .004). Patients on olanzapine had better QOL, nutritional status, and lesser chemotoxicity. Side effects attributable to olanzapine were minimal.

Low-dose, daily olanzapine is a simple, inexpensive, well-tolerated intervention that significantly improves appetite and weight gain in newly diagnosed patients on chemotherapy.