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Mutation Mystery: A Clinician Seeks Answers to Improve Skin Cancer Treatment for Women

July 09, 2015
by Rick Harrison

Peering through a microscope, Dr. Christine Ko sees questions.

As a dermatologist, she often struggles to determine if a type of skin cancer commonly found on women’s legs is slow-growing or more aggressive. But even calling on her extensive experience as a dermatopathologist trained to diagnose skin cancers in the laboratory, the answers remain equally hard to reach.

“We rely so much on what we see,” Ko said. “But there are clues inside these damaged cells that we are missing.”

Ko has launched a study to see if a mutated gene can serve as a biological marker to predict the growth rate and recurrence of squamous cell carcinoma, a type of tumor of the thin outer layer of skin that affects about 700,000 Americans each year. More common in women, this cancer often appears on the lower leg and requires doctors to remove the skin, leaving a large hole that can be painful, difficult to heal or replace with a graft, and lead to complications from multiple removals because of recurring cancer.

Funded by Women’s Health Research at Yale with co-funding from the Yale Comprehensive Cancer Center, the study aims to identify which forms of the cancer are slow-growing so that doctors could treat it much more conservatively than a full excision. Because there is no current way of knowing if the cancer might be more aggressive and potentially life threatening, doctors tend to choose the more aggressive treatment to be safe.

“Sitting at the microscope and seeing this uncertainty in the cell’s appearance, we probably over-diagnose rather than under-diagnose,” Ko said. “If we could figure out a better way, it would be truly helpful to our patients.”

Toward that end, the study seeks to find a distinction in the variety of abnormal sequences, or mutations, seen in a cell’s genetic code. Armed with this new knowledge, doctors could determine which mutations drive the growth and spread of the cancer and which act more like harmless bystanders.

What are those bystander mutations doing there if not contributing to the growth and spread of the cancer? Why would a generally aggressive cancer have fewer mutations than a slower growing cancer, as researchers have observed?

“We just don’t understand the contributions of the mutations that we see,” Ko said. “I’m hoping that my research will shed light on this to guide treatment.”

Not only could better information lead to less invasive treatments with better outcomes, but the research could provide relief to patients who have limited ability and often little interest in grappling with medical uncertainty.

Now that we have more molecular tools available, we can potentially be more precise and save the patient from unnecessary procedures and worry.

Dr. Christine Ko

“They are shouldering the unknown,” Ko said.

And the new study should help clarify the uncertainty, offering a more precise tool to help pathologists fine-tune their already highly developed and acute visual skills.

“The diagnoses that we currently make are based on visual clues,” Ko said. “Now that we have more molecular tools available, we can potentially be more precise and save the patient from unnecessary procedures and worry.”

Ko has no plans to abandon her clinical practice at Yale-New Haven Hospital and enter research full-time. But her new study helps feed her passion to better understand the diseases that affect her patients, reflecting the same passions that drew her first to dermatology and then dermatopathology.

“I wanted to be an internist, and ended up really liking dermatology,” she said. “You can make a difference that’s visible to patients.”

And what appeals to her about studying the diseases under a microscope?

“I like detective work,” she said.


For more news from Women's Health Research at Yale, visit our website or connect with us on Facebook and Twitter.

For questions, please contact Rick Harrison, Communications Officer, at 203-764-6610 or rick.harrison@yale.edu.

Submitted by Carissa R Violante on July 02, 2015

Skin Cancer Facts

What Is a Mutation?

A mutation is a change in a cell’s genetic material during cell division caused by copying mistakes due to exposure to ionizing radiation, exposure to chemicals called mutagens, or infection by viruses. Some cause disease and some are harmless. Mutations that occur in eggs and sperm can be passed on to offspring. Other mutations occur in body cells and are not passed on.

Source: U.S. National Library of Medicine

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Common Types of Skin Cancer

• Melanoma, the most serious type of skin cancer, develops in the cells (melanocytes) that produce melanin — the pigment that gives your skin its color. Melanoma can also form in your eyes and, rarely, in internal organs, such as your intestines.

• The risk of melanoma seems to be increasing in people under 40, especially women. Knowing the warning signs of skin cancer can help ensure that cancerous changes are detected and treated before the cancer has spread. Melanoma can be treated successfully if it is detected early.

• Basal cell carcinoma begins in the basal cells — a type of cell within the skin that produces new skin cells as old ones die off.

• Basal cell carcinoma often appears as a waxy bump, though it can take other forms. Basal cell carcinoma occurs most often on areas of the skin that are often exposed to the sun, such as your face and neck.

• Squamous cell carcinoma of the skin is a common form of skin cancer that develops in the thin, flat squamous cells that make up the outer layer of the skin.

• Squamous cell carcinoma of the skin is usually not life-threatening, though it can be aggressive in some cases. Untreated, squamous cell carcinoma of the skin can grow large or spread to other parts of your body, causing serious complications.

Source: The Mayo Clinic

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Prevention

Most skin cancer is thought to be caused by long-term exposure to ultraviolet (UV) radiation, either from sunlight or from tanning beds or lamps. Avoiding UV light and using sunscreen may help protect against basal cell carcinoma.

In May, researchers published a study in the journal Science finding that 18-32 percent of otherwise healthy skin cells taken from the eyelids of middle-aged subjects contained DNA damage similar to what doctors find in sun-exposed skin and that can lead to cancer.

Dr. Douglas E Brash, Senior Research Scientist in Therapeutic Radiology and in Dermatology and Clinical Professor of Therapeutic Radiology at Yale School of Medicine, published a commentary that ran along with the findings and warned recently in the New York Times that people should take sun exposure more seriously.

“You can’t buy a cream to get rid of mutations, so the best approach is to prevent the damage,” Brash said in the Times. “The new study presents a graphic picture of what’s going on in our skin and might convince people to put on sunscreen and stay off the beach between 10 and 2.”

Source: The Mayo Clinic and Science

Peter J. Campbell et al. High burden and pervasive positive selection of somatic mutations in normal human skin. Science, May 2015 DOI: 10.1126/science.aaa6806

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Facts and Figures

• Each year in the United States, nearly 5 million people are treated for skin cancer. In 2006, in the most recent study available, 3.5 million cases were diagnosed in 2.2 million people.

• Each year there are more new cases of skin cancer than the combined incidence of cancers of the breast, prostate, lung and colon.

Treatment of non-melanoma skin cancers increased by nearly 77 percent between 1992 and 2006.

• Over the past three decades, more people have had skin cancer than all other cancers combined.

• One in five Americans will develop skin cancer in the course of a lifetime.

• Squamous cell carcinoma is the second most common form of skin cancer. An estimated 700,000 cases of this cancer are diagnosed each year in the United States.

• The incidence of squamous cell carcinoma has been rising, with increases up to 200 percent over the past three decades in the United States.

• Organ transplant patients are up to 250 times more likely than the general public to develop squamous cell carcinoma.

• About two percent of squamous cell carcinoma patients – between 3,900 and 8,800 people – died from the disease in the United States in 2012.

Source: The Skin Cancer Foundation