Dalton, who was elected to Parliament in 2023, said: “My constituents deserve an MP to represent them with diligence and conviction.
“Whilst my oral chemotherapy treatment will not stop me from being that champion for West Lancashire, I believe now is the right time to take the reasonable adjustments I need to both manage my condition and focus on being a constituency MP by stepping back from ministerial duties.”
Dalton revealed in January 2025 that she had been diagnosed with breast cancer for a second time.
Responding to her decision to stand down, Streeting wrote on X: “Ashley has been an outstanding minister and has been so in the face of extraordinary adversity.
“She has achieved more as a minister than many politicians achieve in their entire careers.
“I’m so sorry to lose her from our team, but proud of her decision and her impact.”
Writing in The Times, 53-year-old Dalton said she needed to reduce her workload “to serve my constituents as they deserve, whilst adequately managing the side effects of chemo as well as caring for my elderly mum”.
She added: “At present, my disease is stable. Having said that, metastatic breast cancer is incurable. I will never beat it.
“In fact, when people ask when will I know I’ve beaten my cancer, I tell them ‘when I’ve died of something else’.”