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Principal researcher Dr. Nancy Baxter, a cancer surgeon at St. Michael’s Hospital, said drugs used to suppress the immune system to prevent organ rejection likely contribute to a higher rate of cancer.St. Michael's Hospital/The Canadian Press

Patients who undergo liver, kidney or other solid organ transplants are up to three times more likely to die from cancer than those in the general population, a study has found, suggesting that recipients need regular screening to catch malignancies early.

The study of more than 11,000 Ontario transplant patients found that almost one-fifth of the deaths in this group over a 20-year period were cancer-related, with skin cancers among those posing the most significant risk of death.

Of 3,068 deaths among patients who had kidney, liver, heart or lung transplants between 1991 and 2010, 603 were cancer-related, the study by the Institute for Clinical Evaluative Sciences and Toronto's St. Michael's Hospital concluded.

When researchers excluded patients with pretransplant malignancies, the overall rate of cancer deaths was still twice that of the general population. Children who had received a transplant had a higher risk of dying from cancer than organ recipients over 60.

Principal researcher Dr. Nancy Baxter, a cancer surgeon at St. Michael's Hospital, said drugs used to suppress the immune system to prevent organ rejection likely contribute to a higher rate of cancer, which is also often harder to treat in transplant patients.

The powerful medications "suppress the body's response to cancer, so it can be more aggressive," said Baxter, noting the median age of death was about five years after a transplant.

"That's very soon after the transplant, so one wonders if the immunosuppression kicks things into gear."

Transplant patients diagnosed with cancer also may receive less aggressive treatment because of concerns about their having frailer health and a poorer ability to withstand the toxic side-effects of chemotherapy. Fears over potential organ rejection may also play a role, researchers speculate.

Baxter said skin cancers – both melanoma and non-melanoma cancers – are of particular concern for transplant patients, who were found to have a risk of dying from the disease 30 times higher than those in the general population.

While malignant melanoma often has a more dismal outlook, non-melanoma skin cancers like basal- and squamous-cell carcinomas are typically far more curable for the average person.

That's not the case for organ recipients who develop the disease.

"Skin cancer in this transplant patient population, non-melanoma skin cancer, it's a different beast than it is in the general population," Baxter explained.

"I don't want the message to go out to these transplant patients that they're going to die of skin cancer because chances are that they're not," she said. "It's an uncommon cause of death, but still it's a much more aggressive cancer in this patient population.

"So it's really important for them to get that message because there are a number of things that transplant patients can do to reduce their risk of developing and having a serious problem related to skin cancer."

They include avoiding sun exposure and getting regular skin checks, as well as embracing widely recommended cancer-prevention strategies such as not smoking, limiting alcohol consumption, eating a healthy diet and getting regular exercise.

"I think there's a lot of things that people can do to improve outcomes from cancer and I think it's particularly important for transplant patients to do them."

Janet Parr, a former school vice-principal in Guelph, Ont., said Thursday she was warned by doctors after her heart transplant three years ago to be especially wary of the sun's rays and to have her body regularly checked for signs of skin cancer.

"I now have a dermatologist, which I didn't have before, and I have to see that person once a year," said the 54-year-old, who avoids excess exposure to sunlight. "Certainly as a transplant patient, we're well aware that we are at an increased risk."

Still, she doesn't dwell on the fact that her life-saving heart transplant has increased her odds of developing cancer.

"For me personally it doesn't make one bit of difference. I think really what came from having the transplant is how fortunate I am that a donor was found and somebody agreed to be a donor or their family did.

"At this point, I feel that I've got a new life and so that's how I live it, and I try to live it more purposefully. … I think more about life than about dying."

Baxter said cancer is the second leading cause of death in transplant patients after cardiovascular disease, another complication that can arise from treatment related to organ replacement.

However, the death rate from heart attack, stroke and other cardiovascular-related diseases has been decreasing, she said, primarily because health practitioners have intentionally focused on providing more targeted care for transplant recipients.

"It's actually had a really big effect," said Baxter, who would like to see transplant specialists and oncologists collaborating to improve care when it comes to preventing and treating cancer, with the goal of reducing premature deaths.

"I think we have to make sure we have a very tailored approach to these patients." The study was published in Thursday's edition of the journal JAMA Oncology.

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