Pantoprazole Prophylaxis Against Delayed CINV for Patients Receiving Breast Cancer Chemotherapy

Breast Cancer is the most common cancer type in women in New Zealand and has the second highest mortality (Ministry of Health NZ) Many women with early breast cancer still receive chemotherapy, before or after surgery and delayed nausea is a particular challenge. Ensuring tolerable therapy is critical to improving outcomes, by enabling patients to complete optimal anti-cancer therapy and to improve quality of life during therapy. Despite recent advances in antiemetic regimens, recent trials showed that rates of delayed Chemotherapy-Induced Nausea and Vomiting (CINV) are is in excess of 50%, with significant impacts on quality of life during treatment. This suggests that different mechanisms than those targeted by centrally acting anti-emetics account for such symptoms. There is strong evidence that chemotherapy regimens can result in gastrointestinal mucosal injury and dyspepsia. A number of studies have shown chemotherapy-induced dyspepsia can be relieved by a proton pump inhibitor, but none have reported their use as prophylaxis for delayed CINV, which may be a linked symptom. Proton pump inhibitors are widely used in the treatment of non-malignant dyspeptic conditions and are the most potent medications at reducing gastric acid secretions. They are considered safe in short-term use and are commonly used in clinical practice in cancer patients as well as the wider population. The pharmacokinetics Pantoprazole make it the ideal PPI for this study. The experience of New Zealand Medical Oncologists is that delayed nausea is often completely resolved by the delayed use of a PPI when symptoms occur. In this study we hope to see a 30% difference in the rates of delayed nausea by using a drug which is readily available and of very low cost. This will be the first time it has been used as preventive therapy in this setting. If this benefit occurs, it would significantly improve the treatment journey and may improve compliance to anti-cancer therapies.