ISLAMABAD: When Erin Chieze saw an indentation on her breast in December 2015, her conclusion was immediate. "I instantly knew I had breast cancer," she wrote on Facebook, thanks to a breast cancer awareness photo a friend had shared.

"Had I not seen that photo, I would have assumed that it was an indentation from the underwire of my bra," Chieze, 38, a nursing student at West Hills College in Lemoore, California, told CNN.

Within five days of noticing the indentation, she was told she likely had breast cancer. A month later, doctors told her it was stage IV; the cancer had metastasized outside the breast.

"I knew all about self exams," Chieze wrote on Facebook last week, "but a picture of what to look for keyed me into knowing I had a terminal disease."

In telling her story, she found a similar photo online, an egg carton filled with lemons, on the website for a charity called Worldwide Breast Cancer. She shared it on Facebook with an impassioned call to promote awareness with useful, practical information.

Her post with the 15-year-old image has now been shared nearly 42,000 times.