People who've received an organ transplant are almost three times more likely to die from cancer than the general population, a new study reports.
And transplant patients who never had cancer before are nearly twice as likely to die from cancer, the researchers reported.
"We found there was an increased risk of death from almost every cancer," said lead researcher Dr. Nancy Baxter, chief of general surgery at St. Michael's Hospital in Toronto.
"That was in all age groups, but more for younger individuals than older individuals. It seems that cancer is a real burden for transplant patients."
The findings were published in the Jan. 7 online edition of JAMA Oncology.
Cancer was the second-leading cause of death, behind heart disease, for the more than 11,000 transplant patients in the study, Baxter said. The study included information from 1991 to 2010. Transplants included kidneys, livers, hearts and lungs.
There were just over 3,000 deaths in that group, including about 600 related to cancer, the researchers said.
Physicians have been aware that transplant patients are more likely to get cancer, Baxter said, but it wasn't known whether these patients are at greater risk of actually dying from their cancer.
"We haven't known the impact that cancer has on them, because they have a lot of other things going on as well that can affect their health," explained Baxter, who is also an associate professor at the University of Toronto's Institute of Health Policy, Management and Evaluation.
People who've had a transplant are nearly 30 times more likely to die from non-melanoma skin cancers, the study found. In addition, people who've had a transplant are almost 13 times more likely to die from liver cancer, and nearly 10 times more likely to die from non-Hodgkin lymphoma. The risk of dying from bone or soft tissue cancer was about five times higher, the research revealed.
The risk of cancer death in pediatric transplant patients was about 85 times higher than their peers. Transplant recipients older than 60 had the lowest risk of cancer death in the study, but even that was nearly double their peer rate, the investigators found.
Experts believe the immune-suppressing drugs that transplant patients need to prevent rejection of new organs may work against them when it comes to cancer, allowing cancers to grow, Baxter said.
"Our immune system helps us fight cancer. It helps fight off some malignancies," Baxter said. "If you have that dampened down, it may have an impact."
Immune system-suppressing drugs also might hamper the body's ability to target and kill off viruses that cause cancer, Baxter added. For example, human papillomavirus (HPV) can cause cervical cancer, Epstein-Barr virus is linked to lymphoma, and hepatitis B and C viruses can lead to liver cancer, the researchers said.
In this study, people were 6.5 times more likely to die from a cancer caused by an infectious disease, but only twice as likely to die from a cancer not caused by an infection.
Transplant patients also might die because they aren't hardy enough to handle the cancer treatment that a healthy person can take, Baxter suggested.
"They've got a lot going on in terms of their transplants, they're on a lot of medications, and they may not tolerate the kind of aggressive treatment we give for cancer that the average person gets," she said.
However, the cancer risk is not a reason to turn down a transplant, said Dr. Thomas Schiano, medical director of liver transplant for Mount Sinai Health System in New York City.
"The article shouldn't scare patients into avoiding life-saving transplantation or induce them to stop their immunosuppression," Schiano said. "They should work with their transplant team to establish specifics regarding cancer screening, i.e., seeing a dermatologist annually for skin cancer screening," he explained.
"What I have found over the years is that transplant recipients may not undergo American Cancer Society screening guidelines because they get lost in the shuffle," added Schiano, who was not involved with the new study.
"The transplant team only sees them annually and their internists may forget about cancer screening in the setting of the complex post-transplant management, or the patient doesn't give the significance to it," he said.
Baxter added that there also are lifestyle changes that transplant patients can undertake to improve their odds.
For example, she pointed out that in the study more people overall died from lung cancer than any other type of cancer.
"Getting these people to stop smoking is really important, and now that there's lung cancer screening we need to really focus on that as well," she said.