Who is the narrator's brother in the novel, A Girl Is a Half-formed Thing?

The brother, never named, is two to three years older than his younger sister, the narrator. Given chemotherapy and surgery for a cancerous brain tumor when he is younger, the brother spends much of his school days being bullied and made fun of for the scar on his head. When the brother’s cancer returns, it does not respond to treatment. The brother later dies.