Hodgkin lymphoma among US solid organ transplant recipients

Malignancy: An Adverse Effect of Immunosuppression

Benefits of solid organ transplantation in end stage organ diseases are indisputable. Malignancy is a feared complication of solid organ transplantation and is a leading cause of mortality in patients with organ transplantation. Iatrogenic immunosuppression to prevent graft rejection plays a crucial role in the cancer development in solid organ transplant recipients. Chronic exposure to immunosuppression increases the malignancy burden through deregulation of host immune defense mechanisms and unchecked proliferation of oncogenic viruses and malignancies associated with these viruses. Vigorous screening of candidates undergoing transplant evaluation for malignancies, careful assessment of donors, and vigilant monitoring of transplant recipients are necessary to prevent, detect, and manage this life-threatening complication.

Cancer Risks in Solid Organ Transplant Recipients: Results from a Comprehensive Analysis of 72 Cohort Studies

Understanding the cancer risks in different transplant recipients helps early detection, evaluation, and treatment of post-transplant malignancies. Therefore, we performed a meta-analysis to determine the cancer risks at multiple sites for solid organ transplant recipients and their associations with tumor mutation burden (TMB), which reflects the immunogenicity. A comprehensive search of PubMed, Web of Science, EMBASE, Medline, and Cochrane Library was conducted. Random effects models were used to calculate the standardized incidence ratios (SIRs) versus the general population and determine the risks of different cancers. Linear regression (LR) was used to analyze the association between the SIRs and TMBs. Finally, seventy-two articles met our criteria, involving 2,105,122 solid organ transplant recipients. Compared with the general population, solid organ transplant recipients displayed a 2.68-fold cancer risk (SIR 2.68; 2.48-2.89; P <.001), renal transplant recipients displayed a 2.56-fold cancer risk (SIR 2.56; 2.31-2.84; P <.001), liver transplant recipients displayed a 2.45-fold cancer risk (SIR 2.45; 2.22-2.70; P <.001), heart and/or lung transplant recipients displayed a 3.72-fold cancer risk (SIR 3.72; 3.04-4.54; P <.001). The correlation coefficients between SIRs and TMBs were 0.68, 0.64, 0.59, 0.79 in solid organ recipients, renal recipients, liver recipients, heart and/or lung recipients, respectively. In conclusion, our study demonstrated that solid organ transplant recipients displayed a higher risk of some site-specific cancers, providing individualized guidance for clinicians to early detect, evaluate, and treat cancer among solid organ transplantation recipients. In addition, the increased cancer risk of solid organ transplant recipients is associated with TMB, suggesting that iatrogenic immunosuppression may contribute to the increased cancer risk in transplant recipients. (PROSPERO ID CRD42020160409).

Classic Hodgkin lymphoma post-transplant lymphoproliferative disorders (PTLD) are often preceded by discordant PTLD subtypes

Classic Hodgkin lymphoma (CHL) is the rarest post-transplant lymphoproliferative disorder (PTLD) subtype. Few cases of patients with metachronous discordant PTLD episodes including CHL-PTLD have been reported, but the incidence of and risk factors for this phenomenon are unknown. Patients with CHL-PTLD were identified from an institutional PTLD database. Of 13 patients identified with CHL-PTLD six (46%) had antecedent non-CHL-PTLD: three had polymorphic PTLD, two monomorphic PTLD, and one nondestructive PTLD. Patients with prior metachronous non-CHL-PTLD were younger at transplant and had a longer latency time to CHL-PTLD post-transplant. The prevalence of EBV seronegativity at transplant was high in both groups, but prolonged high-level EBV DNAemia only occurred in some with metachronous non-CHL-PTLD. In conclusion, patients with CHL-PTLD have metachronous non-CHL-PTLD diagnoses with discordant histology more commonly than previously recognized. Primary EBV infection with chronically elevated EBV viral loads may represent unique risk factors for CHL-PTLD following an initial non-CHL-PTLD event.

De novo malignancy in organ transplant recipients in Taiwan: a nationwide cohort population study

Organ transplant recipients appear to have a higher risk of de novo malignancy. The aim of the study was designed to estimate cancer risk in heart, lung, kidney and liver transplant recipients. The cohort study used the Taiwan National Health Insurance Research Database (1996-2011) and followed the outcomes of organ recipients until 2012. De novo cancer and mortality rates after organ transplantation were evaluated using standardized incidence ratios, excess absolute risks of cancer, and standardized mortality ratios in recipients were compared with those in the general population. We identified 40, 231, 2, and 115 patients who developed cancer after heart, kidney, lung, and liver transplantation, which corresponded to a cancer incidence of 878.4, 1101.2, 728.9, and 1361.4 cases per 100,000 person-years, respectively. In heart, kidney, lung, and liver recipients, the overall standardized incidence ratios were 1.65 (1.21-2.24), 3.33 (2.93-3.79), 1.82 (0.45-7.27) and 3.37 (2.81-4.05) and the overall standardized mortality ratios were 5.45 (4.96-5.98), 1.47 (1.34-1.61), 8.92 (7.10-11.20), and 3.83 (3.48-4.20), respectively. These results reveal a three-fold increase in de novo cancer risk in organ transplant patients compared with the general population. This study illustrated the importance of de novo malignancy after organ transplantation.

Daunting but Worthy Goal: Reducing the De Novo Cancer Incidence After Transplantation

Solid-organ transplant recipients are at increased risk of developing de novo malignancies compared with the general population, and malignancies become a major limitation in achieving optimal outcomes. The prevention and the management of posttransplant malignancies must be considered as a main goal in our transplant programs. For these patients, immunosuppression plays a major role in oncogenesis by both impairement of immunosurveillance, enhancement of chronic viral infection, and by direct prooncogenic effects. It is essential to manage the recipient with a long-term adapted screening program beginning before transplantation to use a prophylaxis to decrease infection-related cancer, to propose a viral monitoring, and to modulate the immunosuppression toward lower doses especially for calcineurin inhibitors. Indeed, strategies to induce tolerance or to allow a dramatic reduction of the immunosuppression burden are the more promising approaches for the reduction of the posttransplant malignancies.

Cancer Risk After Pediatric Solid Organ Transplantation

BACKGROUND

The effects of pediatric solid organ transplantation on cancer risk may differ from those observed in adult recipients. We described cancers in pediatric recipients and compared incidence to the general population.

METHODS

The US transplant registry was linked to 16 cancer registries to identify cancer diagnoses among recipients <18 years old at transplant. Standardized incidence ratios (SIRs) were estimated by dividing observed cancer counts among recipients by expected counts based on the general population rates. Cox regression was used to estimate the associations between recipient characteristics and non-Hodgkin's lymphoma (NHL) risk.

RESULTS

Among 17 958 pediatric recipients, 392 cancers were diagnosed, of which 279 (71%) were NHL. Compared with the general population, incidence was significantly increased for NHL (SIR = 212, 95% confidence interval [CI] = 188-238), Hodgkin's lymphoma (SIR = 19, 95% CI = 13-26), leukemia (SIR = 4, 95% CI = 2-7), myeloma (SIR = 229, 95% CI = 47-671), and cancers of the liver, soft tissue, ovary, vulva, testis, bladder, kidney, and thyroid. NHL risk was highest during the first year after transplantation among recipients <5 years old at transplant (SIR = 313), among recipients seronegative for Epstein-Barr virus (EBV) at transplant (SIR = 446), and among intestine transplant recipients (SIR = 1280). In multivariable analyses, seronegative EBV status, the first year after transplantation, intestine transplantation, and induction immunosuppression were independently associated with higher NHL incidence.

CONCLUSIONS

Pediatric recipients have a markedly increased risk for many cancers. NHL constitutes the majority of diagnosed cancers, with the highest risk occurring in the first year after transplantation. NHL risk was high in recipients susceptible to primary EBV infection after transplant and in intestine transplant recipients, perhaps due to EBV transmission in the donor organ.

Primary Intestinal Hodgkin Lymphoma Mimicking Intraabdominal Abscess in a Renal Transplant Recipient: A Case Report

INTRODUCTION

Post-transplant lymphoproliferative disease (PTLD) comprises a variety of lymphoid and plasma cell disorders arising in patients with a solid organ transplant. Monomorphic lymphomas represent the most significant part of this wide spectrum, with the overall risk rising with the aggressiveness of lymphoid proliferation in comparison to the general population. The development of Hodgkin lymphoma is very rare in transplant recipients, comprising less than 6% of all monomorphic PTLD, while cases of primary intestinal Hodgkin lymphoma in these circumstances are anecdotal.

CASE REPORT

We describe an exceptional case of intestinal Hodgkin lymphoma mimicking an intra-abdominal abscess that developed in a transplant recipient 19 years after kidney transplantation. By presenting this case, we wish to emphasize the importance of suitable diagnostic pathways in transplant recipients experiencing prolonged fever episodes or masses of unknown origin, thus raising the awareness of possible PTLD development in such patients.

CONCLUSION

The lack of information about transplant recipients with Hodgkin PTLD regarding the site of involvement and type of treatment suggests the necessity of conducting larger international studies aimed at providing further insight into this particular group of patients.

Risk of lymphoid neoplasms in a Swedish population-based cohort of 337,437 patients undergoing appendectomy

OBJECTIVE

Appendectomy remains one of the most common surgical procedures, but possible long-term consequences for health and disease are incompletely investigated. The appendix forms part of the secondary lymphoid system and appendectomy has been associated with increased risks of hematolymphoproliferative malignancies in some studies.

MATERIALS AND METHODS

We examined the risk of lymphoid neoplasms in a large cohort of 337,437 appendectomised patients <60 years of age in Sweden 1975-2009. We estimated relative risks of non-Hodgkin lymphoma (NHL) and major subtypes, Hodgkin lymphoma (HL), chronic lymphocytic leukaemia (CLL), myeloma, and acute lymphoblastic leukaemia (ALL) versus the general population using standardised incidence ratios (SIRs) with 95% confidence intervals (CIs).

RESULTS

There was no increased risk of NHL (SIR = 0.97, 95%CI 0.88-1.06), major NHL subtypes, CLL (SIR = 0.87, 95%CI 0.70-1.06), myeloma (SIR = 1.14, 95%CI 0.96-1.33) or ALL (SIR = 1.10, 95%CI 0.80-1.47) following appendectomy. An increased risk of HL was observed among patients diagnosed with appendicitis (SIR = 1.29, 95%CI 1.07-1.54, p=0.007), especially individuals aged <20 years at surgery (SIR = 1.43, 95%CI 1.11-1.82), and for the nodular sclerosis subtype of HL (SIR = 1.55, 95%CI 1.01-2.27). A marginally increased risk of myeloma was noted among men, but the association was limited to the first few years of follow-up.

CONCLUSION

Appendectomy is not associated with any notable increase in risk of lymphoid neoplasms. A small increased risk of HL following appendicitis (rather than appendectomy per se) could reflect a true association, or shared susceptibility to infection/inflammation among individuals prone to develop HL. The association observed for myeloma may be explained by chance or surveillance bias.

Comparison of Cancer Diagnoses Between the US Solid Organ Transplant Registry and Linked Central Cancer Registries

US transplant centers are required to report cancers in transplant recipients to the transplant network. The accuracy and completeness of these data, collected in the Scientific Registry of Transplant Recipients (SRTR), are unknown. We compared diagnoses in the SRTR and 15 linked cancer registries for colorectal, liver, lung, breast, prostate and kidney cancers; melanoma; and non-Hodgkin lymphoma (NHL). Among 187 384 transplants, 9323 cancers were documented in the SRTR or cancer registries. Only 36.8% of cancers were in both, with 47.5% and 15.7% of cases additionally documented solely in cancer registries or the SRTR, respectively. Agreement between the SRTR and cancer registries varied (kappa = 0.28 for liver cancer and kappa = 0.52-0.66 for lung, prostate, kidney, colorectum, and breast cancers). Upon evaluation, some NHLs documented only in cancer registries were identified in the SRTR as another type of posttransplant lymphoproliferative disorder. Some SRTR-only cases were explained by miscoding (colorectal cancer instead of anal cancer, metastases as lung or liver cancers) or missed matches with cancer registries, partly due to recipients' outmigration from catchment areas. Estimated sensitivity for identifying cancer was 52.5% for the SRTR and 84.3% for cancer registries. In conclusion, SRTR cancer data are substantially incomplete, limiting their usefulness for surveillance and research.

Lymphoproliferative Disorders after Lung Transplantation: Clinicopathological Characterization of 16 Cases with Identification of Very-Late-Onset Forms

BACKGROUND

The incidence of posttransplant lymphoproliferative disorders (PTLD) has recently declined, but late cases are increasingly reported in lung transplant recipients.

OBJECTIVES

We present our experience with PTLD after lung transplantation, attempting to examine the distinguishing characteristics of early versus late cases.

METHODS

We have reviewed clinical and pathological data of all cases occurring in our institution between 2001 and 2014.

RESULTS

Patients, aged 15-63 years, were mostly (12/16) Epstein-Barr virus (EBV) seropositive at the time of transplantation. Eleven early cases, occurring 9.4 ± 5.2 months after transplantation and mostly (9/11) prior to 2010, had EBV+ diffuse large B-cell lymphomas. Lungs and/or thoracic lymph nodes were often involved (n = 8). Treatments included reduction of immune suppression (n = 11), rituximab (n = 8) and chemotherapy (n = 7). Two patients are in complete remission at 26 and 216 months. Nine patients died 8.0 ± 6.5 months after PTLD diagnosis. Of the 5 cases with late PTLD occurring 4-23 years (mean ± SD: 10.4 ± 7.7) after transplantation (and 3/5 after 2009), 1 had pulmonary lymphomatoid granulomatosis (only endothoracic case), 1 cutaneous large T-cell lymphoma, 2 had anaplastic large cell lymphomas, and 1 Hodgkin's disease. Two of the 5 cases were EBV-, including one followed by a second EBV+ PTLD after 8 years of complete remission. Two patients were alive and well (follow-up: 44 and 151 months), one having suffered from EBV-related cholestatic hepatitis 6 years after the PTLD.

CONCLUSION

Our small experience shows a trend toward (very) late occurrence, associated with more unusual clinicopathologic features, but not with a worse prognosis.

Time Trends in Rates of Hodgkin Lymphoma Histologic Subtypes: True Incidence Changes or Evolving Diagnostic Practice?

BACKGROUND

Histologic subtypes of classical Hodgkin lymphoma [cHL; e.g., nodular sclerosis, mixed cellularity, not otherwise specified (NOS)] are epidemiologically and prognostically distinctive. Therefore, unexplained, ongoing incidence rate declines for mixed cellularity and increases for NOS require examination.

METHODS

We analyzed detailed histology-specific Hodgkin lymphoma incidence rates in 1992 through 2011 U.S. SEER data (n = 21,372) and reviewed a regional subset of 2007 through 2011 NOS pathology reports for insight into diagnostic practices.

RESULTS

cHL rates were stable until 2007, then decreased for whites [annual percent change (APC) and 95% confidence interval (CI), -3.6% (-5.6% to -1.5%)]. Nodular sclerosis rates declined after 2007 by 5.9% annually, with variation by gender, age, and race/ethnicity. In 1992 through 2011, mixed cellularity rates declined [APC -4.0% (-4.7% to -3.3%)], whereas NOS rates rose [5.3% (4.5%-6.2%)] overall and in most patient groups. The 2007-2011 NOS age-specific rates were more similar to mixed cellularity rates for 1992-1996 than 2007-2011. Trends in combined rates were minimal, supporting increasing misclassification of mixed cellularity, lymphocyte depletion, and specific nodular sclerosis subtypes as NOS. Eighty-eight of 165 reviewed NOS pathology reports addressed classification choice. Twenty (12.1%) justified the classification, 21 (12.7%) described insufficient biopsy material, and coders missed specific subtype information for 27 (16.4%).

CONCLUSION

Recent nodular sclerosis rate declines largely represent true incidence changes. Long-term rate decreases for mixed cellularity and other less common subtypes, and increases for NOS (comprising ∼30% of cHL cases in 2011), likely reflect changes in diagnostic and/or classification practice.

IMPACT

Diminishing histologic subtyping undermines future surveillance and epidemiologic study of Hodgkin lymphoma. Guideline-based use of excisional biopsies and more coding quality control are warranted.

Immunodeficiency-associated viral oncogenesis

Several viruses with different replication mechanisms contribute to oncogenesis by both direct and indirect mechanisms in immunosuppressed subjects after solid organ transplantation, after allogeneic stem cell transplantation, or with human immunodeficiency virus (HIV) infection. Epstein-Barr virus (EBV), human papillomavirus (HPV), Kaposi sarcoma herpesvirus (KSHV), human T-cell lymphotropic virus type 1 (HTLV-1) and Merkel cell polyoma virus (MCV) are the main viruses associated with the development of cancer in immunosuppressed patients. Besides being a main cause of immunodeficiency, HIV1 has a direct pro-oncogenic effect. In this review, we provide an update on the association between the condition of acquired immunodeficiency and cancer risk, specifically addressing the contributions to oncogenesis of HPV, MCV, KSHV, HTLV-1, and EBV.

The epidemiology of cancers in human immunodeficiency virus infection and after organ transplantation

The authors provide an update on the association between immune deficiency and cancer risk in people with human immunodeficiency virus (HIV) and in solid organ transplant recipients. Over the past decade, it has become clear that a wider range of about 20 mostly infection-related cancers occur at increased rates in people with immune deficiency. The human herpes virus 8 (HHV8) and Epstein Barr Virus (EBV)-related cancers of Kaposi sarcoma (KS) and non-Hodgkin lymphoma (NHL) are most closely related to level of immune deficiency. Transplant recipients also have a greatly increased risk of squamous cell carcinoma (SCC) of the skin, related to direct carcinogenic effects of the pharmaceuticals used for immune suppression. For those three cancer types, the increased cancer risk is largely reversed when immune deficiency is decreased by treatment of HIV or by reduction of iatrogenic immune suppression. Other infection-related cancers also occur at increased rates, but it is not clear whether reduction of immune deficiency reduces cancer risk. Prostate and breast cancer do not occur at increased rates, providing strong evidence that these cancers are unlikely to be related to infection. Epidemiological and clinical trends in these two populations have led to substantial recent changes in cancer occurrence.

Disparate survival and risk of secondary non-Hodgkin lymphoma in histologic subtypes of Hodgkin lymphoma: a population-based study

We compared survival outcomes and rates of secondary non-Hodgkin lymphoma (NHL) in 28 323 patients with nodular lymphocyte predominant (NLPHL) and classical Hodgkin lymphoma (HL) from the Surveillance, Epidemiology and End Results database, diagnosed between 1995 and 2010. In a multivariate analysis NLPHL demonstrated a significantly better relative survival (5-year risk of lymphoma-related death 5.7%, hazard ratio [HR] 0.46, p < 0.0001) than the reference nodular sclerosis (NSHL) subtype (5-year risk 12.7%). Lymphocyte-rich classical HL had outcomes comparable to NSHL (5-year risk 14.3%, HR 0.84, p = 0.11). Exceptionally poor outcomes were observed in lymphocyte depleted HL (5-year risk 48.8%, HR 2.26, p < 0.0001). The risk of secondary NHL was increased in NLPHL (HR 2.81, p < 0.001) and lymphocyte-rich classical HL (HR 2.27, p = 0.002), but not in other subtypes compared with NSHL. In conclusion, the histologic classification retains a significant prognostic value in HL and the disparities between the subtypes warrant customized treatment and surveillance strategies.

Risk of lymphoma subtypes after solid organ transplantation in the United States

BACKGROUND

Solid organ transplant recipients have high risk of lymphomas, including non-Hodgkin lymphoma (NHL) and Hodgkin lymphoma (HL). A gap in our understanding of post-transplant lymphomas involves the spectrum and associated risks of their many histologic subtypes.

METHODS

We linked nationwide data on solid organ transplants from the US Scientific Registry of Transplant Recipients (1987-2008) to 14 state and regional cancer registries, yielding 791 281 person-years of follow-up for 19 distinct NHL subtypes and HL. We calculated standardised incidence ratios (SIRs) and used Poisson regression to compare SIRs by recipient age, transplanted organ, and time since transplantation.

RESULTS

The risk varied widely across subtypes, with strong elevations (SIRs 10-100) for hepatosplenic T-cell lymphoma, Burkitt's lymphoma, NK/T-cell lymphoma, diffuse large B-cell lymphoma, and anaplastic large-cell lymphoma (both systemic and primary cutaneous forms). Moderate elevations (SIRs 2-4) were observed for HL and lymphoplasmacytic, peripheral T-cell, and marginal zone lymphomas, but SIRs for indolent lymphoma subtypes were not elevated. Generally, SIRs were highest for younger recipients (<20 years) and those receiving organs other than kidneys.

CONCLUSION

Transplant recipients experience markedly elevated risk of a distinct spectrum of lymphoma subtypes. These findings support the aetiologic relevance of immunosuppression for certain subtypes and underscore the importance of detailed haematopathologic workup for transplant recipients with suspected lymphoma.

Surgical lung biopsy in transplant patients with diffuse lung disease: how much worse when the lung is the graft?

BACKGROUND

There are no data that compare the clinical presentation and results of surgical lung biopsy (SLB) for diffuse lung disease (DLD) in lung transplant patients, in contrast to individuals with other type of solid organ grafts. Our objective was to compare the clinical picture, radiologic pattern, pathology results, and outcomes of SLB for DLD in these two subsets of patients.

METHODS

We retrospectively reviewed the clinical records of transplant patients undergoing SLB for DLD at our institution between 2004 and 2011. Patients with lung transplants and those with other transplants were compared.

RESULTS

During the study period, 1,232 solid organ transplants were done at our institution. Of these, 49 patients (4%) had DLD that needed SLB for diagnosis, and 24 of these patients had a lung transplant. Dyspnea and a radiologic reticular pattern were more frequent in lung transplant patients, 21 of 24 vs 11 of 25 (p = 0.001) and 14 of 24 vs 7 of 25 (p = 0.03), respectively. Although postoperative complications and in-hospital deaths were more common in lung transplant patients, the differences were not statistically significant. Having the SLB performed for diagnosis, as opposed to being conducted for DLD that did not improve on medical treatment, had a protective effect on multivariate analysis (hazard ratio, 0.39; 95% confidence interval, 0.16 to 0.96; p = 0.042). A prior lung transplant was the only independent predictor of survival (hazard ratio, 4.62; 95% confidence interval, 1.53 to 13.92, p = 0.006).

CONCLUSIONS

It is relatively uncommon for a solid organ transplant patient with DLD to require a SLB. Clinical and radiologic presentation differ in patients with lung transplants compared with other transplants. Postoperative outcomes are not significantly different between the groups. SLB performed early in the course of the disease might be beneficial. Having a lung transplant is a significant negative predictor of survival.

Comparison of de novo cancer incidence in Australian liver, heart and lung transplant recipients

Population-based evidence on the relative risk of de novo cancer in liver and cardiothoracic transplant recipients is limited. A cohort study was conducted in Australia using population-based liver (n = 1926) and cardiothoracic (n = 2718) registries (1984-2006). Standardized incidence ratios (SIRs) were computed by cancer type, transplanted organ and recipient age. Cox regression models were used to compare cancer incidence by transplanted organ. During a median 5-year follow-up, the risk of any cancer in liver and cardiothoracic recipients was significantly elevated compared to the general population (n = 499; SIR = 2.62, 95%CI 2.40-2.86). An excess risk was observed for 16 cancer types, predominantly cancers with a viral etiology. The pattern of risk by cancer type was broadly similar for heart, lung and liver recipients, except for Merkel cell carcinoma (cardiothoracic only). Seventeen cancers (10 non-Hodgkin lymphomas), were observed in 415 pediatric recipients (SIR = 23.8, 95%CI 13.8-38.0). The adjusted hazard ratio for any cancer in all recipients was higher in heart compared to liver (1.29, 95%CI 1.03-1.63) and lung compared to liver (1.65, 95%CI 1.26-2.16). Understanding the factors responsible for the higher cancer incidence in cardiothoracic compared to liver recipients has the potential to lead to targeted cancer prevention strategies in this high-risk population.

Treatment of kidney transplant recipients with ACEi/ARB and risk of respiratory tract cancer: a collaborative transplant study report

Whether treatment with angiotensin-converting enzyme inhibitors (ACEi) and/or angiotensin receptor blockers (ARB) increases the risk of cancer is controversial. Collaborative transplant study data were analyzed according to whether kidney transplant recipients were treated with ACEi/ARB at year 1. Twenty-four thousand and ninety patients were studied of whom 9079 (38%) patients received ACEi/ARB. There were 872 nonskin malignancies during years 2-8 posttransplant, including 107 respiratory/intrathoracic tumors. The standardized incidence ratio (SIR) for all nonskin malignancies was similar between the ACEi/ARB (1.91) and no ACEi/ARB (1.81) groups (p = 0.42). For respiratory/intrathoracic tumors, however, SIR was significantly higher with ACEi/ARB (1.65 vs. 1.09 for no ACEi/ARB, p = 0.033). Multivariate Cox regression analysis showed that ACEi/ARB treatment was not associated with an increased risk of respiratory/intrathoracic tumors in nonsmokers. In patients with a history of smoking, however, the risk of respiratory/intrathoracic tumors was 2.77 (95% CI 1.19-6.43, p = 0.018) in patients without ACEi/ARB treatment as compared to 7.10 (95% CI 3.27-15.4, p < 0.001) in patients treated with ACEi/ARB. Our data indicate that in kidney transplant recipients, ACEi/ARB treatment is associated with a significant increase in the rate of respiratory/intrathoracic tumors in the subpopulation of patients with a history of smoking.