Mr Alexander, 40, is taking part in the Edinburgh Marathon on May 27 to raise money for the charity, after the disease affected his grandmother, aunt and sister.
The advertising and PR consultant said: “I am running for Breast Cancer Care because several members of my family have at some point in their lives been diagnosed with the condition.
“I found that the charity provides fantastic support, reassurance and guidance for those affected by breast cancer, by understanding the individual’s needs throughout treatment.”
Events officer Dawn Stanley said: “The money Tommy raises will be used to support the charity’s services, which offer emotional support, practical advice and a wide range of local support services. ”