How long does targeted therapy take to work for gastrointestinal stromal tumour?

Gastrointestinal stromal tumour, also called GIST, may cause pain, bleeding, fullness or bowel changes, although symptoms do not always track tumour activity. A tumour can become less active before it becomes smaller, and some treatment changes can alter its appearance on imaging. Your team may use CT or another scan, symptom review, examination and blood tests to interpret the overall response. The planned interval between scans helps make the comparison meaningful.

Take each dose as directed and tell your team about vomiting, diarrhoea, missed tablets or difficulty swallowing. Keep a record of abdominal pain, bleeding, bowel changes, appetite and weight, and bring it to reviews. Check before starting another medicine or supplement, because some products can change how targeted therapy is handled by the body. Continue treatment until your prescriber gives different instructions.

Contact your care team promptly for new bleeding, black stools, persistent vomiting, worsening abdominal pain, fever, severe diarrhoea or marked weakness. Seek urgent help for heavy bleeding, a rigid or very swollen abdomen, fainting, chest pain or trouble breathing. These symptoms can require immediate assessment even while scans are showing treatment response.

Ask when your next scan will be done, whether the aim is to measure size or activity, and which symptoms should improve first. Ask how to handle a missed dose, which medicines interact with your treatment, and what scan findings would prompt a change in the plan.