Are breast cancer and melanoma linked diseases? What to know after Sarah Ferguson reveals 2nd cancer diagnosis

An inherited gene mutation could put you at a higher risk of both cancers.

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Sarah Ferguson, Duchess of York, has been diagnosed with a second cancer. (Photo by Stephen Pond/Getty) SANDRINGHAM, NORFOLK - DECEMBER 25: Sarah Ferguson, Duchess of York attends the Christmas Morning Service at Sandringham Church on December 25, 2023 in Sandringham, Norfolk. (Photo by Stephen Pond/Getty Images)
Sarah Ferguson, Duchess of York, has been diagnosed with a second cancer. (Photo by Stephen Pond/Getty)

Sarah Ferguson, the Duchess of York, recently shared a surprising diagnosis of melanoma shortly after getting the all-clear from breast cancer, raising questions about a link between the two diseases.

The British author, 64, was diagnosed with breast cancer in the summer of 2023, and during a reconstructive surgery following her mastectomy, she had several moles removed and tested. One was found to be cancerous, People reported, confirming Ferguson was diagnosed with malignant melanoma.

"The Duchess wants to thank the entire medical team which has supported her, particularly her dermatologist whose vigilance ensured the illness was detected when it was," the a representative for Ferguson told People.

Clearly, another diagnosis so soon after treatment for breast cancer has been distressing, but the Duchess remains in good spirits.Representative, via People

Ferguson isn't the only one to receive a melanoma diagnosis shortly after having breast cancer. A 2011 study in the U.S. found female breast cancer survivors younger than 45 years old had a 38 per cent higher risk of developing melanoma as a second cancer compared to the general population. Female breast cancer patients 45 years and older had a 12 per cent increase in the risk.

However, an expert tells Yahoo Canada this doesn't mean breast cancer causes melanoma, or vice-versa. We spoke with Dr. Marcus Butler, the multidisciplinary diseases lead for melanoma skin oncology at Princess Margaret Cancer Center in Toronto.

Here's what you need to know.

What do we know about breast cancer and melanoma?

Breast cancer and melanoma are two common cancers among light-skinned women in Canada. (Getty)
Breast cancer and melanoma are two common cancers among light-skinned women in Canada. (Getty)

Breast cancer is the most common cancer among Canadian women and is the second leading cause of death from cancer in Canadian women, according to Canadian Cancer Society. One in eight women in Canada are estimated to develop breast cancer.

Malignant melanoma is the most serious type of skin cancer and is responsible for the most deaths — about 900 a year, the Canadian Skin Cancer Foundation said. This cancer can develop from the same skin cells that create moles, and most commonly appears on the back and legs.

What are the risk factors for breast cancer and melanoma?

Dr. Butler explained both breast cancer and melanoma are notably common among light-skinned people, especially women.

Inherited genetic mutations — especially genes BRCA and BRCA2 — can put you at higher risk of developing breast cancer. Other risks for breast cancer include, among others: dense breasts, reproductive history, exposure to ionizing radiation, hormone replacement therapy, oral contraceptives and lifestyle choices like alcohol intake, obesity and physical inactivity.

For melanoma, the highest risk factor is exposure to the sun and other UV rays. "And also, light skin, especially red hair is associated with a high risk of developing melanoma," Butler added. Other risks also include the number of moles a person has, use of tanning beds and history of skin cancers.

There are some shared risk factors between the two.

"BRCA2, that has an association with breast cancer, also has an increased risk of developing skin cancer," Butler claimed.

Does having breast cancer mean a higher risk of melanoma?

According to Butler, it's crucial to understand that the link between breast cancer and melanoma doesn't stem from one being a risk factor for the other. While they share genetic factors, the environmental risks for each cancer remain separate.

"Breast cancer itself does not put you at higher risk of developing melanoma," he claimed. Rather, it means if you have a BRCA2 mutation, you have a higher risk of both breast cancer and melanoma (and other cancers).

"Your average patient who develops breast cancer from other causes is not at increased risk of developing melanoma, and the same is also true for patients who develop melanoma just because they use tanning beds or had excessive sun exposure when you're younger."

How common is it to get melanoma after breast cancer and should I worry?

Close up view of a young woman with curly red hair sitting on the floor, leaning on a sofa and looking away with a sad face.
The expert recommends monitoring for melanoma risk every six months. (Getty)

Butler acknowledged that while the incidence of melanoma following a breast cancer diagnosis isn't dramatically increased in Canada, it's not an entirely uncommon scenario, especially among fair-skinned women.

He underscored the importance of considering genetic testing, particularly for those with a family history of cancers.

"If you have never been tested for these familial syndromes, it's worthwhile asking your doctor about it and and having testing done to see if you have inherited a syndrome... It may change the surveillance strategy."

For those going through a breast cancer diagnosis, seeking advice from genetic counselors is recommended. Monitoring for melanoma risk involves regular dermatologic assessments every six months, offering a proactive approach to early detection.

Breast cancer itself does not put you at higher risk of developing melanoma.

Butler said identifying and treating melanoma at its early stages improves the chances of curing it with a straightforward surgical excisional procedure, "than it is to deal with more advanced disease."

As a specialist in skin cancer, Butler advised Canadians to abstain from tanning beds to lower their risk factors for melanoma.

"No one should use tanning beds at all. I strongly recommend against it, because it's a potent carcinogen — it's like smoking," he said.

When it comes to breast cancer, he emphasized more research is needed to advance diagnosis and treatment outcomes for women.

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