I read it at least 20 years ago and I’m fairly sure it was in a readers digest book (I was a tad precocious as a child)
The basics are:
Written in the first person, from the perspective of a young female doctor who worked with children. One child had a lump on their testes and it developed into cancer.
The cancer went into remission and I think the mum got pregnant again.
Eventually though (either in the first book or a sequel) the cancer came back and the boy died.
The reason I’m looking for it is someone close to me recently died and for some reason I’m really quite fixated on finding this book from my childhood.
If anyone could help I would be eternally grateful.