Cassie McKee mistook her first colon cancer symptoms for food poisoning in 2017. When the active mom’s sudden nausea didn’t subside, she feared she might be having complications from a recent C-section. Cassie, who was 38 at the time, had given birth to her second daughter four months previously. Her older daughter was 2 years old.

A CT scan revealed a significant colon obstruction.

“My doctor told me to go check myself...