A Facebook Timehop photo recently gave one woman insight into how long she possibly had skin cancer before she was given an official diagnosis. 

Deborah Crofts told the Daily Mail that one of her wedding photos recently popped up through Facebook's Timehop function, which shows older posts and photos users have shared on the social media site. The British mother, who learned she had skin cancer a year after her 2007 wedding, noticed in the photo that the cancer was visible on her chest on her wedding day. At the time, she said she noticed the mark but didn't know it was cancerous:

It became a scab during her honeymoon, but she said she still didn't feel concerned about it. Then, a year later, she visited a doctor to inspect another mark on her body, but her physician was particularly concerned about the one on her chest. She was diagnosed with basal cell carcinoma, a cancer that is "thought to be caused by long-term exposure to ultraviolet (UV) radiation from sunlight," according to the Mayo Clinic.

"I was shocked and frightened when I was given my diagnosis," she told the Daily Mail. "However, I felt able to take it in my stride, because I was reassured I could have surgery to remove the cancerous cells and that I wouldn’t need chemotherapy."

She added that looking back at other photos of her in 2008 made her see how obvious the cancer that was on her chest once appeared.

Crofts' experience points to a health scare facing millions of people.

Skin cancer is the most common form of cancer; signs usually include changes to the skin, oozing, bleeding, scaliness, the spread of color, and a change in skin sensation. About 5.4 million basal and squamous cell skin cancers are diagnosed annually, according to the American Cancer Society. 

A 2014 study published in the journal Cancer Epidemiology, Biomarkers & Prevention found that people with a lot of moles, fair skin or red hair are especially vulnerable to skin cancer if they get lots of sun exposure early in life. The findings also revealed that having five blistering sunburns between ages 15-20 can significantly increase a person's risk of developing skin cancer.

Read the full Daily Mail story here.