Just one year after having taken his seat in the National Assembly, Lewis was diagnosed with bowel cancer in December 2017. It was found that the disease had already spread to other parts of his body, and he was not expected to recover. He spoke openly about fighting the illness and how he was coping. He died at
Ystrad Fawr Hospital in
Ystrad Mynach on 11 January 2019. Tributes were paid to him from all parties in the Assembly.
Adam Price, leader of Plaid Cymru said: He was succeeded by
Delyth Jewell, who had been second on Plaid's list in the region at the 2016 election. His funeral was scheduled for 25 January at St Luke's Church,
Abercarn, followed by burial at the local cemetery. ==Personal life==