Single Lung Transplants Increase Lung Cancer Risk, Study Shows
Single lung transplant patients with idiopathic pulmonary fibrosis (IPF) have a higher risk of developing lung cancer, according to a recent study — and these cancers are more likely to be diagnosed at an advanced stage and carry a worse prognosis.
Thus, the researchers recommend prioritizing people with IPF in need of lung transplants for double lung transplants. These patients also should be closely monitored post-surgery for early cancer detection, they said.
The study, “Characteristics of lung cancer in idiopathic pulmonary fibrosis with single lung transplant versus non-transplanted patients: a retrospective observational study,” was published in the journal BMJ Open Respiratory Research.
IPF is known to be associated with an increased incidence of lung cancer, with an estimated incidence of 4.4–13.0%, compared with 0.007–0.016% in the general population.
A lung transplant often is the only treatment option for increasing life expectancy in people with end-stage IPF. However, the immunosuppressive regimen that is required after a transplant to prevent organ rejection increases the risk for lung cancer.
A team of researchers from the Rabin Medical Center and Tel Aviv University, both in Israel, reported observing a higher rate of lung cancer among IPF patients after lung transplant surgeries, compared with people with IPF who did not receive transplants. To better understand this observation, they conducted a retrospective analysis of all IPF patients diagnosed with lung cancer at the Rabin Medical Center over an 11-year period.
From records between January 2008 and December 2018, the group identified 205 people with IPF who received lung transplants. Among them, 122 received a single lung transplant and 83 had a double lung transplant.
A total of 15 transplant patients (12.3%) were later diagnosed with lung cancer. For comparison, out of 497 people with IPF who did not receive a transplant during the same time period, 45 (9.1%) developed lung cancer.
Although the incidence of lung cancer was higher in the transplanted group than in the non-transplanted group, this difference did not reach statistical significance.
However, differences between the groups became much clearer when those who received lung transplants were separated into subgroups for single and double transplants. All 15 transplant patients who developed cancer had received single lung transplants. In addition, in all these cases, the cancer was found in the native, or non-transplanted, lung.
The different rates of cancer appeared to be specific to lung cancer. Both the patients who received transplants and those who did not developed other cancers at similar rates. For instance, the rate of squamous cell carcinoma, a type of skin cancer, was 40% among those who had received transplants versus 42.2% among patients who did not have a transplant. Similarly, individuals who received lung transplants had a 26.7% rate of developing adenocarcinoma, a cancer of the glands, versus 37.8% among those who did not have a transplant.
Among those with lung cancer, the average time interval from an IPF diagnosis to that of cancer was three years in the group that did not receive a transplant, compared with 10 years in the group that had transplants. Lung cancer was typically diagnosed at already advanced stages — stages 3 to 4. In all, 10 transplanted patients (66.7%) were diagnosed at stage 4, compared with 34 patients (44.4%) who did not receive transplants.
The researchers found the advanced stage of the cancer at diagnosis notable, as hospital protocols call for annual chest screening for all IPF patients who receive transplants. They suggested that cancerous tissue may be more challenging to detect in fibrotic lungs, and that immunosuppressive treatments commonly prescribed after major surgeries might accelerate cancer progression.
Regarding survival, the transplanted patients lived for an average of four months following their lung cancer diagnosis, compared with 11 months among those who did not receive transplants. Only 27% of those receiving transplants lived for more than 12 months past diagnosis, compared with 43% in the group that did not have transplants.
As a retrospective study, the results come with certain caveats, the team noted. One of them is the fact that the study relied upon the accuracy of historical data. In addition, because the study involved a relatively small number of patients, it was not possible to detect significant differences between groups for many study parameters.
Despite such limitations, the results indicate a relationship between single lung transplants and the development of lung cancer, the investigators said.
“Our study showed that single lung transplant IPF patients are at increased risk for [lung cancer], which will more likely be diagnosed at an advanced stage with a worse prognosis,” the researchers wrote, adding that “patients with IPF considered for transplant should therefore be prioritised for double lung transplants.”
Among IPF patients who receive a single lung transplant, “vigilant post-transplant screening should be implemented for early [lung cancer] detection,” the team added.