More than 1,100 people with high-risk melanoma took part in a phase three trial.

This is the third stage of testing a treatment, usually involving many people.

Phase three is a large test of a treatment before regulators consider whether to approve it.

This is a large study that checks a treatment before officials decide whether to allow its use.

The researchers randomly assigned participants to receive either the vaccine or a placebo as well.

A placebo is something given in a study that looks like the real treatment but has no active medicine.

A placebo is a treatment that looks like the real one but does not contain the active medicine.

Here, it means a treatment made to look real but without the active medicine.

In the group that received Keytruda with a placebo, the figure was 70 percent.

The group received something that looked like the vaccine but had no active medicine.

In the vaccine group, 88.5 percent were alive without distant spread at two years, compared with 80 percent in the Keytruda-and-placebo group.

The placebo group received something that looked like the real treatment but had no active medicine.

The main result reported was recurrence-free survival: the time people live without their cancer returning.

This is the length of time people live without their cancer coming back.

A mutation is a change in genetic material.

Here, it means a change in the material that carries genetic information.

It uses synthetic mRNA, a set of instructions that cells can use to make a protein.

It is a made-in-a-lab form of mRNA, which carries instructions that cells can use to make a protein.

The reported results also measured distant metastasis-free survival.

This measures how long people live without cancer returning or spreading to another part of the body.

Alex, what do we know about side effects, and how far along is the treatment toward routine use?

These are unwanted effects that a treatment can cause.

A researcher in the trial described the main side effects as a sore arm, tiredness, and other reactions like those seen with mRNA coronavirus vaccines.

These are unwanted reactions to the treatment, such as a sore arm or tiredness.

Longer follow-up can show whether the difference continues, and the process of making an individual vaccine will matter if the treatment moves toward wider use.

Follow-up means continued checking over time after the main results are collected.

The two-year results are encouraging, but longer follow-up is still under way.

Follow-up means continued observation of the participants over time.

Grace has explained the trial’s early results and why longer follow-up matters.

This means continuing to observe the participants for a longer time.

The important point is that this is a tailored treatment, added to an existing cancer medicine.

The treatment is designed for the needs or cancer of a particular patient.

Alex has shown how the vaccine is tailored and what its preparation involves.

The vaccine is made to suit the individual patient.

The two-year results are encouraging, but longer follow-up is still under way.

It means the longer period of observation is happening now and has not finished.