I am the only person in my family who has survived cancer. My mother died of leukemia when I was 29, my father and stepfather died of stomach and jaw cancer (respectively) when I was 31, my father-in-law died of lung cancer when I was 35, and my sister-in-law died of lung cancer when I was 44.

So when I was diagnosed with stage IIA invasive ductal carcinoma — a type of breast cancer — in June 2015, telling my children was probably...