Trial results for therapeutic cancer vaccines have been promising enough that the approach is being extended to additional tumour types. The terminology causes confusion, so it is worth being precise about what these are.
Not preventive
An ordinary vaccine trains the immune system before exposure. These do the opposite: they are given to someone who already has cancer, and they train the immune system to recognise the tumour that is already present.
The word vaccine is used because the mechanism is the same – presenting the immune system with a target so it learns to attack it. Everything else about the situation is different.
Why cancer is hard for the immune system
Because tumour cells are the patient’s own cells. The immune system is specifically built not to attack those, and it is good at that job.
Tumours also actively suppress immune responses locally, and they mutate, so a population that is being attacked shifts towards variants that are not recognised.
What changed
Personalisation. Rather than targeting something common to many tumours, sequencing an individual patient’s tumour identifies mutations unique to it, and a vaccine is manufactured against those specific targets.
That is genuinely individual medicine – a product made for one person, which is why it took so long to become practical. Sequencing had to get cheap and fast, and manufacturing had to compress from months to weeks.
The realistic picture
Results are strongest in combination with other immunotherapy rather than alone, and strongest in preventing recurrence after surgery rather than shrinking established tumours.
Response rates are meaningful but not universal. Some patients respond dramatically, others not at all, and predicting which in advance remains unsolved.
What it means practically
Available in trials and for specific indications, not as general treatment. Cost is high and manufacturing capacity is limited.
This is reporting on research, not advice. Treatment decisions belong with an oncologist who knows the specific case.