The chief executive of NHS Suffolk has announced she is leaving the post.
Carole Taylor-Brown, 53, said the move was a "tough decision" but had followed doctors' advice to reduce her working commitments.
She conquered breast cancer in 2008 and suffered a serious spinal infection which has left her in persistent and severe pain, NHS Suffolk said.
Trust chairman Alastair McWhirter said: "Carole truly has done the very best for people in Suffolk."
He added: "Her drive and leadership has helped the NHS in Suffolk to make some incredible achievements.
"The board and I are very sorry to lose her yet understand her decision to leave.
"We wish her all the very best for the future."
NHS Suffolk said Mrs Taylor-Brown has led NHS Suffolk to "immense achievements", including eradicating the £35m historic debt, quicker cancer and hospital treatment times and more dentists and screening services.
"People in Suffolk deserve the very best care and getting the best for people in Suffolk has always been my passion," said Mrs Taylor-Brown.
She will leave NHS Suffolk at the end of September and the NHS shortly afterwards.