Who is Oleg Filimonovich Kostoglotov from Cancer Ward and what is their importance?

Oleg is a citizen of the Soviet Union in the 1950s. He recently spent eight years in prison camps because of Article 58, a law that gave the Soviets considerable leeway in sending unwanted people to Siberia for extended times. Oleg now lives in Ush-Terek, on the steppes, and is a topographer's assistant there. He was diagnosed with cancer when he was in the camps, but results of a biopsy were lost in government files. He is a patient on the Cancer ward.