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Transcript: Gastrointestinal side effects

Last updated:20th May 2024
Published:20th May 2024

Dr Gary Lyman

All transcripts are created from interview footage and directly reflect the content of the interview at the time. The content is that of the speaker and is not adjusted by Medthority.


GI side effects associated with cancer therapies, including both traditional cytotoxic therapies, and the more novel targeted therapies, are quite common, as was mentioned. And, they are particularly distressing to many patients. The symptoms of nausea/vomiting, particularly severe diarrhoea, mucositis, esophagitis, these all can pose a particularly high impact on patients' quality of life, and their willingness to continue cancer therapy.
We've done a lot of work in the area of cancer-associated nausea and vomiting. And, I've had the privilege of chairing the initial guideline from the American Society of Clinical Oncology on this topic, other professional organisations have done the same. And, they're pretty much harmonised across the guidelines in terms of recommendations.
They all recognise that there may be an early onset of nausea and vomiting from chemotherapy, probably due to a peripheral pathway and serotonin release from the GI tract, impacting on the vagal nerve and resulting at a brainstem effect, as well as some agents causing a delayed chemotherapy-induced nausea and vomiting two to five days following chemotherapy, from a somewhat different pathway mechanism. The guidelines start off by classifying the risk of chemotherapy-induced nausea and vomiting into high risk, more than 90% risk of nausea and vomiting, intermediate risk, somewhere between 30 and 90%, and low risk, between 10 and 30%. Anything less than 10% is considered minimal risk. Fortunately, there are a number of new antiemetic agents that have emerged since I began clinical practise many years ago. And, combinations of these have emerged as highly effective at controlling the risk of chemotherapy-induced nausea and vomiting in patients with cancer. So, the most common ones used for acute nausea and vomiting are the 5-HT3 antagonists, ondansetron and granisetron, and delayed nausea and vomiting, the NK-1 antagonist such as fosaprepitant are perhaps more effective at reducing these more delayed effects.
We've also recently introduced the antipsychotic, olanzapine, which has a greater affinity for the serotonin receptors. And, this can be very effective in the very high-risk patient setting. And, of course, we often add dexamethasone, a steroid, because of the impact of inflammation on the risk and severity of chemotherapy-induced nausea and vomiting. I find I just emphasise how important it is to prevent this, if at all possible. So, empiric prophylactic treatment from the start of therapy is really important to reduce both the onset of what we call anticipatory chemotherapy-induced nausea and vomiting, where a patient begins to have symptoms even before getting their treatment as they anticipate the coming treatment and possible nausea and vomiting. But also too, of course, to enhance continued compliance with effective chemotherapy regimens. So preventing these, where at all possible, is fundamentally important.