How long does immunotherapy take to work for stomach cancer?

Some people notice changes early, while others need more time before a response can be identified. Treatment may continue while the cancer is stable or responding and side effects remain manageable.

Immunotherapy helps the immune system recognise and attack cancer cells. Because this immune response develops differently from person to person, a scan soon after treatment begins may not give the full picture. Your oncologist compares scans over time and considers appetite, pain, energy, weight changes and other symptoms alongside the images.

A change in symptoms alone cannot confirm whether treatment is working. Symptoms can also be affected by the cancer, another treatment, infection or an immune-related side effect. The treatment plan may be adjusted if scans show growth, symptoms worsen, or side effects require a pause or different care.

Attend each infusion and review appointment unless your cancer team advises otherwise. Keep a brief record of new symptoms, their start date, medicines you take, eating and drinking, bowel changes, skin changes and your energy. Bring this record to appointments so the team can compare changes with examination findings and scans.

Do not stop immunotherapy or start supplements without discussing them with your oncology team. Ask when your next scan is planned, what result would count as a response, and whether another treatment is being given alongside immunotherapy.

Contact your cancer team promptly for new or worsening breathlessness, chest pain, severe diarrhoea, persistent vomiting, marked abdominal pain, yellowing of the skin or eyes, a widespread rash, confusion, severe weakness, or a fever. These symptoms can need assessment during immunotherapy and should not wait for the next scan or infusion.

Use the emergency service if symptoms are severe, rapidly worsening, or make it difficult to breathe, stay awake or keep fluids down. Tell the clinician that you are receiving immunotherapy and provide the name of the medicine if you know it.

Useful questions include: When will my response be checked? Which symptoms should I report the same day? How will you interpret a scan if the findings are uncertain? What other treatments are part of my plan? How will we decide whether to continue, pause or change immunotherapy?