Carol, played by Lindsey Coulson, will find a lump in her breast just before Christmas. After an appointment with her doctor, she is referred to a specialist for further tests and is diagnosed with the illness in the New Year.
Scenes airing in early 2014 will see Carol's family deal with the implications of her diagnosis.
The emotional storyline will also see the return of Natalie Cassidy as Carol's daughter Sonia.
Speaking of her new storyline, Coulson commented: "This is a very important storyline as breast cancer is something that affects so many people. Through Carol's story I hope we can raise awareness of the impact of breast cancer on the people that have it and their families."
EastEnders' executive producer Dominic Treadwell-Collins added: "EastEnders has a long tradition of dealing with social issues and breast cancer is one that the majority of people have been affected by in some way. And this is not just a story about breast cancer. This is a story about women, about mothers and daughters, and ultimately about family.
"And with Lindsey Coulson, Michael French, Patsy Palmer and Natalie Cassidy giving powerhouse performances at its centre, this is a storyline that will inform, move, and shake up the audience as it shakes up the Jackson family."
EastEnders producers have worked with breast cancer experts and charities, including Macmillan Cancer Support, to ensure a realistic and sensitive portrayal of the issue.
Jacqui Graves, Head of Health and Social Care at Macmillan Cancer Support, said: "Sadly, thousands of women like Carol are diagnosed with breast cancer every year in the UK, so we congratulate EastEnders for helping to raise awareness of the condition.
"Being diagnosed with cancer can have a devastating impact, not just on the individual, but their families and friends as well. That's why it's vital people get the help and support they need at this difficult time. We hope anyone watching who is affected by the issue comes to Macmillan Cancer Support for advice by calling our helpline on 0808 808 00 00 or visiting our website."
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