Christopher Diamond met the victim in a pub where the cancer sufferer was having a rare day out socialising with friends.
Truro Crown Court heard when her friends drifted away, Diamond made a beeline for her even though she tried to get away from him.
She ended up very drunk and Diamond escorted her home from the pub – but did not leave and went into her home in Truro, Cornwall.
She was ill several times and put herself to bed and he raped her as she slept.
The court heard she woke to find him in her home – and he left his underwear when he departed.
Judge Simon Carr said over the next few days she pieced together what had happened and scientific evidence backed up that he had had sex with her without her consent.
Father of one Diamond, of Chi Hesken, Park Kerwys, was convicted of raping the woman in May 2022.
Diamond, who now also have cancer, was jailed for seven years and placed on the Sex Offenders Register for life.