What is the main conflict in Cancer Ward by Aleksandr Isaevich Solzhenitsyn?

The Cancer Ward is a novel about a Soviet man, Oleg Kostoglotov, who is admitted to a Soviet hospital somewhere in Asia, and is treated for several months for a tumor. As Oleg communicates with his fellow patients and interacts with the physicians treating him, he learns to define himself and his future. Emerging from years of prison camps and exile, Oleg discovers he still has the capacity to love. He also learns that even a strong man as himself can be brought down by disease, and can be brought down by the overwhelming cruelty of the Soviet system.