Whats the rarest cancer case youy have ever come across and how many people have had it?

Question: Whats the rarest cancer case youy have ever come across and how many people have had it?

Asked by sophandjack to Claire on 20 Jun 2010 in Categories: Your Research.
- Claire O'Donnell answered on 20 Jun 2010:
  
  i remember doing some work about a strange blood cancer that affected how the blood clots and there are some very rare brain tumours. Looking back I’ve only done 1or 2 of each in the past 10 years or so and since I work over a population of 6.5 million that’s not many is it?

Question: Whats the rarest cancer case youy have ever come across and how many people have had it?