Question: do people have cancer when they are born?

Blanka Sengerova answered on 25 Jun 2012:

This is a very interesting one, thank you for asking it.

Some people are predisposed to cancer when they are born, which means that they are much more likely to get it. This can be the result of some mistakes in the DNA that makes them up that has been inherited from their parents, and that unfortunately means they might develop cancer at a very young age when some of their cells start dividing uncontrollably at the expense of others in their body. It does mean that you sometimes hear about childhood cancers in heartbreaking stories of toddlers who have to have chemotherapy.

Many other cancers occur as a result of gradual damage of your DNA throughout your life. This can be radiation such as sunlight, X-rays you’re exposed to but also damage by chemicals that are found in the environment. Damage to a cell’s DNA is all in a day’s work, and cells have got very sophisticated repair mechanisms to fix their DNA (what I work on!) because there may be something like 10,000 damage events per cell per day, most of which are fixed. When the repair mechanisms fail and enough damage events occur in one cell, the cell may then self-destruct (called apoptosis) to prevent it from causing a problem. If this failsafe mechanism fails, the cell may start signalling in such ways that it will continually keep dividing and not stop like a normal well behaved cell should. This is what leads to cancer (tumours are lumps of uncontrollably dividing cells). Most of the latter cancers will only manifest themselves in later life.

So yes, there are some cancers that you are born with (or more accurately that occur in early life), and others occur later on. But what you are definitely born with is a predisposition for cancer.