When a new cancer treatment is being considered it has to go through many tests to make sure it is both safe and of benefit.
If tests in the laboratory (known as preclinical testing) have been promising then the treatment can be tested in people (this is clinical testing, or clinical trials). These trials follow a set pattern through various Phases, from Phase 1-4.
A Phase 1 trial simply looks at the side-effects and dose of the treatment in order to work out a safe way of using it.
If the Phase 1 trial is successful then Phase 2 trials can be begin. The Phase 2 trials are intended to see whether the treatment might be effective against cancer.
The usual pattern for Phase 2 trials is for the new treatment to be given to groups of people with different types of advanced cancer. Because the drug is new, and its benefits are unknown, it is usually only people who have cancers which are no longer controlled by conventional treatment who are considered for Phase 2 studies (since it would be wrong to give someone a treatment of uncertain value, when there are tried and tested treatments already available which could be helpful).
For each type of cancer which it is tested against, the new treatment is initially given to about 15 to 20 people. If some of those people show an improvement as a result of having the treatment then more people with that particular type of cancer will be tested to try and get a more accurate idea of how active the treatment is. In this way doctors can decide whether it is likely to be useful and also decide which cancers are most likely to be controlled by the new treatment.
Unfortunately only a minority new treatments which reach the Phase 2 stage prove to be of value against cancer. This means that taking part in a Phase 2 trial does not guarantee any benefit in terms of tumour control, and increased life expectancy. In fact it could involve extra inconvenience (with hospital visits and regular check-ups) and possible side effects from the treatment. So the chances of getting a further remission by taking part in a Phase 2 trial are usually quite small. Many people with advanced cancer do volunteer for these studies, partly in the hope that they may get a benefit and also to help medical science and possibly help other people in the future.
Another word of caution is that Phase 2 trials often get misreported by the media. Newspaper articles, TV programmes or internet pages will often suggest that these studies are a 'breakthrough' or are using a 'wonder drug' and so, understandably, people think the drug is far more promising than is the case.