Sarah Ferguson is being treated for skin cancer − and her diagnosis is an important reminder for all of us about the prevalence of the disease and the importance of wearing adequate SPF.

Her melanoma was discovered when several moles were removed while the Duchess of York, 64, was undergoing reconstructive surgery following a mastectomy, her representative told The Associated Press. Her skin cancer diagnosis comes just six months after her breast cancer diagnosis.

"Clearly, another diagnosis so soon after treatment for breast cancer has been distressing but the Duchess remains in good spirits," her rep said in a statement. Her doctors are determining if the malignancy was caught early.

How often should you wear sunscreen?

Dr. Barry D. Goldman, a clinical instructor at Cornell NewYork-Presbyterian Hospital, previously told USA TODAY that 80-90% of all skin cancers are on the face and neck.

"I've seen many tumors on the eyelids or around the eyes, the forehead. Basically, the whole face should be covered... We think of the whole face as a high-risk area for skin cancer," he said. 

Dr. Samer Jaber, also a dermatologist, tells his patients at Washington Square Dermatology to use sunscreen every day on the entire face.

"We know regular use of sunscreen on the face both prevents against skin cancer and is great for anti-aging, preventing wrinkles and discoloration on the face," he previously said, adding that it's also important to wear SPF on non-sunny days since UVA rays can penetrate clouds and windows.

More:Lloyd Austin didn’t want to share his prostate cancer struggle. Many men feel similarly.

How much sunscreen should you use?

Dr. Caroline Robinson, a dermatologist and founder of Tone Dermatology, added that it should be applied to any other uncovered areas as well, including the neck, ears and hands.

"The American Academy of Dermatology recommends applying 1 shot glass of sunscreen to cover the entire body, approximately 1/2 teaspoon of which will cover the face and neck. Your sunscreen should be at least an SPF 30, broad spectrum protecting against both UVA and UVB rays and water resistant," she added. "It should be worn daily regardless of whether you are indoors or outdoors and reapplied during the day especially if outdoors."

In addition to sunscreen, the American Academy of Dermatology Association suggests seeking shade when appropriate as well as wearing sun-protective clothing, including wide-brimmed hats, long sleeves and sunglasses.

The association also encourages patients to see a board-certified dermatologist if they notice new or suspicious spots on the skin, or anything changing, itching or bleeding.

In order to notice any changes, the association says it's beneficial to get in the habit of checking your skin monthly.

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Khloe Kardashian, Hugh Jackman and more stars who have faced similar issues

Some of your favorite stars have shared important reminders about skin health.

In 2022, Khloe Kardashian took to her Instagram Stories to clear up why she's been photographed with an "ever-evolving bandage" on her face the past few weeks.

"After noticing a small bump on my face and assuming it was something as minor as a zit, I decided to get it biopsied 7 months after realizing it was not budging," she wrote alongside a photo of the bump in question. 

A few days later, she was told she needed to have "an immediate operation to remove a tumor from my face."

Luckily, her doctor was able to get "everything," and she's now in the healing process.

She added she was sharing her story to remind her followers to "get checked, and frequently."

"Please take this seriously and do regular self-exams as well as your annual checkups," she urged fans.

More:Khloe Kardashian's facial tumor, Jesse Tyler Ferguson's skin cancer: What to know about SPF

In August 2021, Hugh Jackman shared a video of himself with a bandage on his nose, explaining his doctors saw something "irregular" and decided to do a biopsy.

"So if you see a shot of me with this on, don't freak out," the actor said before urging his followers to take care of their skin. "Remember, go and get a check and wear sunscreen. Don't be like me as a kid, just wear sunscreen."

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He reiterated his message in the caption of the video: "Please get skin checks often, please don’t think it won’t happen to you and, above all, please wear sunscreen."

In a post to Instagram, "Modern Family" star Jesse Tyler Ferguson also urged his followers to make regular visits to see a dermatologist and wear sunscreen after getting "a bit of skin cancer" removed from his neck. In the photo, you can see a bandage covering a section of his neck just below his ear.

Who is Sarah Ferguson?

The news about Ferguson broke less than a week after the royal family announced that Princess Kate had been hospitalized for unspecified abdominal surgery and that King Charles III was undergoing treatment for an enlarged prostate.

Ferguson, aka "Fergie," was married to Prince Andrew from 1986 to 1996 and they share two grown daughters: Princess Beatrice, 35, and Princess Eugenie, 33. The former senior working royal, who is the author of several children's books and a historical romance, was an obsession of the British tabloids for years before attention turned to Prince William and Prince Harry.

Last June, when Ferguson revealed her breast cancer diagnosis after a routine mammogram, she said her prognosis was good and she was symptom-free.

Ferguson has long advocated for cancer research. In 2022, the Duchess of York and her princess daughters virtually met cancer patients and nurses for the opening of the hematology ward at University College London Hospitals NHS Foundation Trust.

More:Sarah Ferguson shares malignant melanoma diagnosis just months after breast cancer

Contributing: Sara M Moniuszko, Kim Willis