Clare Daly of Kirby, England died this past December from advanced melanoma that she had mistaken for a pulled muscle for months. The tragic story reminds us that although melanoma is one of the most treatable forms of cancer when caught early, if left to progress, it can be deadly.

Not long after her wedding last summer, Daly, a beauty manager for Clarins, a French luxury cosmetics company, began to complain of a pain in her shoulder, The Liverpool Echo reported. Daly believed a pulled muscle was at the root of her discomfort, but despite seeing a physical therapist, the soreness grew. Eventually, the 29-year-old was diagnosed with a very aggressive melanoma linked to a mole she had removed years earlier.

According to the Skin Cancer Foundation, a melanoma is the most dangerous form of skin cancer, and grows when unrepaired DNA damage to skin cells, most often caused by the sun or tanning beds, triggers mutations that cause skin cells to multiply rapidly. These types of tumors often resemble moles and are nearly always curable when recognized and treated early. Unfortunately, when left untreated for too long, the cancer can advance and spread, and in some cases even become fatal.

According to Daly’s friends and family, the naturally fair-skinned blonde was by no means a sun-worshipper and would even don long sleeves and a hat when visiting the beach. The signs of her cancer were hard to find, and she went months without realizing the severity of her shoulder pain. Daly and her new husband, Paul Daly, opted to try dual therapy to help fight the aggressive cancer, but found it difficult to cover the costs for the fairly new treatment.

“We thought dual therapy was the best chance of prolonging Clare’s life, of keeping the cancer at bay for as long as possible in the hope of them finding another new treatment,” Clare’s brother Michael McNally told The Liverpool Echo. “It isn’t funded by the NHS [National Health Services] so we started to fundraise, but it was just too late.”

More than 800 people attended Daly’s funeral, remembering the newlywed as a beautiful and happy-go-lucky woman. In her memory, Daly’s friends and family started The Clare Daly Foundation to help raise awareness about the dangers of sun- and tanning-bed exposure and inspire others to get tested.

“Melanoma is the fifth biggest killer of young women and it’s so easy to protect against if you understand when the UVAs are most harmful,” Stefanie McCartney-Washington, Daly’s childhood friend, told The Liverpool Echo. “It’s not about preaching and saying ‘don’t go in the sun,’ it’s about making everyone aware and more careful.”

Moles are usually harmless, but in some cases, such as Daly’s, they can be deadly. Some of the biggest warning signs of melanoma are inconsistencies in mole appearance. Individuals who find their moles have become asymmetric, developed an uneven border, or changed in color, and overall shape and size are advised to seek a professional opinion immediately.