The latest Horizon, subtitled Teenagers vs Cancer: a User’s Guide (BBC Two), made a determined effort not to wallow in sadness. I thought, initially, that narrator Jack Whitehall was trying too hard to be chipper: “Being a teenager can be pretty rubbish. So imagine what it’s like to throw cancer in the mix.” But then I remembered being chastised by a friend who had breast cancer for doing my “sympathetic face”, which I think involved me thinning my lips into the smile of a simpleton. No one wants that, and this documentary showed how patients refused to be mollycoddled or pitied.

Chloe Thurlow, from Bristol, had been diagnosed with lymphoma but embraced the indignities which the disease had thrust upon her. “I look like a little golden kiwi fruit,” she said as she tried on a new wig. This remark seems throwaway but I think it was important, if you think how self image is a constant cause of anxiety for most teenagers. As Roger Daltrey, frontman of The Who and a patron of the Royal Marsden Hospital in London said: “That’s a time when a spot on your nose is a big deal.”

Nick attempting to get back to normality after chemotherapy gave him heart failure Credit: BBC

Matt defied his aggressive form of leukaemia by having an ironic tattoo of the grim reaper on his leg. Nick, who also had leukaemia and had been plagued by feelings of isolation, took part in an event for fellow sufferers called Find Your Sense of Tumour. Optimism and laughter abounded.

Many stories were unspeakably sad. Chloe Drury died after developing a rare and fast-moving form of bone cancer. Her family’s lives had to be radically recalibrated when she became ill and there was a defiance in their refusal to return to normal. When she died, her mother campaigned tirelessly to try to lower the age at which someone can take part in a drugs trial. Currently, there is a shortage of early-stage clinical trials testing new cancer drugs in children, thus impeding any efforts to improve survival rates from paediatric cancers. In a documentary that strove hard to be cheerful, it was this important point which resonated the most.