Lung Transplant Recipients at Heightened Risk of Colorectal Polyps

By Matthew Phelan

February 04, 2021

NEW YORK (Reuters Health) - Lung transplant patients are at increased risk of developing colorectal adenomas in the first few years after transplantation, possibly warranting enhanced surveillance for colorectal cancer (CRC), a new study suggests.

"When we looked at our data, we saw that these patients are developing polyps faster," lead author Dr. David Row of St. Joseph's Hospital and Medical Center in Phoenix told Reuters Health by phone. "Even in patients who had a negative pre-transplant colonoscopy, a significant portion of them still had polyps at the one-year follow-up."

Solid-organ-transplant recipients are known to be at elevated cancer risk, a link that could be mediated by their use of immunosuppressive medications, Dr. Row and colleagues explain in the Journal of the American College of Surgeons. Yet most CRC-screening recommendations for these patients do not differ from guidelines for the general population, they add.

Lung recipients in particular often require high levels of immunosuppression and so "may be at exceptional risk for developing colon and rectal malignancies," the researchers write.

To investigate, they looked at data on all 411 lung transplant patients treated between 2013 and 2017 at their institution, one of the highest-volume lung-transplant centers in the U.S. The center's post-transplant protocol involves surveillance colonoscopy one to two years after transplantation.

After excluding those who died within a year of transplantation, had a history of CRC, had undergone prior lung transplant, had cystic fibrosis, or lacked a pretransplant colonoscopy, they were left with a group of 237 patients. Their median age was 64 years, and 69% had a history of smoking; most were Caucasian (86%) and 60% were men.

The two most common indications for transplant were chronic obstructive pulmonary disease (43%) and idiopathic pulmonary fibrosis (42%). Most were immunosuppressed with a combination of prednisone, tacrolimus and mycophenolate mofetil.

Ninety-two patients (39%) had one or more adenomas on pre-transplant colonoscopy, while adenomas were found in 50% of the patients between one and five years after transplantation. Just over two-thirds of the posttransplant adenomas were found at year 1.

"The majority of adenomas were identified proximal to the splenic flexure, supporting the need for total colonoscopy over sigmoidoscopy," the researchers note.

Patients with pretransplant adenomas were significantly more likely to harbor polyps following transplantation than were those with a negative pretransplant colonoscopy (63% vs. 41%). There were no cases of CRC.

These rates are "higher than the detection rate for average-risk screening in the general population (25%-30%)," Dr. Row and his colleagues point out, demonstrating "the need for an enhanced CRC surveillance protocol for lung transplant patients."

"Those under consideration for lung transplantation should undergo a total colonoscopy as part of the pretransplant evaluation," they write. "We suggest that patients receive their first post-transplant colonoscopy at 1 year, and subsequently, every 2 years thereafter. Further, organ-specific studies of transplant patients are required prior to the establishment of formal screening and surveillance recommendations."

Dr. Eric Engels of the National Cancer Institute's Division of Cancer Epidemiology and Genetics, in Rockville, Maryland, who was not involved in the research, told Reuters by phone that the study "provides some useful information, but it's one piece of a bigger picture."

Stressing the high mortality of lung-transplant recipients and the fact that polyps may or may not turn cancerous within a patient's lifetime, he said it's important to look at the balance between benefits and risks of heightened CRC surveillance in this population.

"There's the cost of colonoscopy," said Dr. Engels, "and there is the potential complications for these patients who are immunosuppressed and might have other medical problems." Those complications include infection stemming from the colonoscopy procedure itself, a risk that is elevated for lung recipients due to high levels of immunosuppression.

"It's not that screening could not, or should not, be implemented," he said. "It's just that there needs to be a more sophisticated effort to model the pros and cons."

SOURCE: https://bit.ly/3tmMCce Journal of the American College of Surgeons, online January 20, 2021.

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