Home Office Minister James Brokenshire, who was diagnosed with lung cancer two years ago, is taking leave to have surgery on a lung tumour.
The Old Bexley and Sidcup MP resigned as Northern Ireland secretary in 2018 for surgery to remove a lesion on his right lung.
On Monday he confirmed that “frustratingly” there had been a recurrence of a tumour there.
He said he was in “good hands” with the “fantastic NHS team” looking after him.
“[I’m] keeping positive and blessed to have the love of Cathy and the kids to support me through this,” the 52-year-old wrote on Twitter.
Prime Minister Boris Johnson Boris Johnson said his thoughts were with Mr Brokenshire and his family.
“Wishing you all the best for your treatment and looking forward to welcoming you back on the team soon,” he added.
Home Secretary Priti Patel said she was “saddened” by the news, adding: “All my thoughts and prayers are with James and his family during this time”.
“All colleagues across government send James our love and best wishes, and we look forward to having him back soon,” she added.
Health secretary Matt Hancock was among government colleagues wishing him well, adding he was “sending my best wishes for a speedy recovery”.
Labour leader Sir Keir Starmer tweeted: “Wishing you all the best for your treatment, James. Get well soon.”
Mr Brokenshire, who was first elected to Parliament at the 2010 general election, has also previously served as housing secretary under former PM Theresa May.
He has called for efforts to “break some of the stigma around lung cancer” and raise awareness of the disease.