A small number of children will be diagnosed with the disease before adulthood. A larger number are trying to cope with close family being diagnosed. Even more again are worried about their Auntie Megan, or Kylie Minogue, or Mr Roberts, the piano teacher, or their best friend Rhys, because his mother's just died.
Rest assured that most of them will have heard about cancer and started to form ideas, even fears about it. Teachers already give lessons on the emotional roller-coaster of life. They are in the habit of straight talking when it comes to puberty, reproduction and sexual health, yet cancer is not recognised by the national curriculum and remains swept under the carpet.
If education is a preparation for life, we ought to be saying something about a serious illness that one in three of us will get. Young people have told us, at Macmillan Cancer Support, that they want to know more so they can try to protect themselves from it and support people who do have it.
A recent Cancerbackup survey reveals this is a big issue for UK teenagers: 70 per cent know someone who has, or has had, cancer; 74 per cent say they would not know what to say to a friend with cancer; and 50 per cent say they would avoid talking to them about it.
More worryingly, a third think that cancer can be caused by knocks and bumps, while more than one in 10 thinks it is "catching".
Last week, a number of schools in Wales took part in Macmillan's Cancertalk Week. Aimed at pupils aged seven to 16, schools were encouraged to hold lessons or special assemblies on cancer to increase pupils' awareness, aid discussion and dispel some of the myths and unnecessary fears that surround it.
Other schools opted to do last week's fundraiser, The Big Hush (a sponsored silence), and also a writing competition. All of these activities fit in nicely with the curriculum for PSE.
Teachers can access Cancertalk Week's resources on a website which has all the resources for giving talks on the subject.
The free teaching pack for schools, much of which is bilingual, includes a booklet offering information and practical advice for teachers and youth group leaders, activity sheets, teachers' notes and a DVD. Last summer, Macmillan also launched its new YouthLine - a free cancer helpline for 12 to 21-year-olds that also provides help for adults wanting to support affected children or young people.
Bringing cancer out of the shadows and into the classroom, within the context of a responsible and carefully planned discussion, will be rewarding for all concerned.
* www.macmillan.org.ukcancertalk Macmillan YouthLine: 0808 808 0800 (9am-10pm, Monday-Friday) email@example.com
Carys Thomas is Macmillan Cancer Support's communications manager in Wales