The 43-year-old Good Morning Britain presenter revealed that she was terrified to find a lump on her breast and is encouraging woman to have regular cancer checks.
Writing in The Sun, mum-of-three Susanna, told the story of her experience including her relief at being given the all-clear by doctors.
Susanna Reid at the BAFTA Awards
The former Strictly Come Dancing competitor came across the lump after a play fight with her three sons Jack, Sam and Finn.
"I thought to myself: 'For the sake of my boys please don't let it be cancer'," she said, before undergoing a mammogram which revealed that the lump was a harmless cyst.
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Susanna has since praised the work of the CoppaFeel! campaign, which aims to encourage people, particularly younger women, to check their breasts regularly to help detect cancer as early as possible .
The Bristol University graduate described CoppaFeel!'s founder Kris Hallenga as "inspirational" for setting up the charity after being diagnosed with breast cancer when she was just 23.