The role of Cytomegalovirus (CMV) in development of post-transplant de novo cancer is not established. Previous studies have suggested that CMV exposure is associated with an increased overall risk of cancer and in particular, risk of certain types of cancers such as cancer of lung, prostate, oesophagus, uterus and colon. In contrast, one study showed higher incidence of cancer among CMV-naÏve recipients. However, these studies have been relatively small and included kidney recipients only. Here we report the data from a large national registry assessing the impact of CMV exposure on incidence of post transplant cancer.

The data from the National Transplant Registry was linked with the data from the Office for National Statistics to identify all cases of first diagnosis of post-transplant cancer (other than non-melanoma skin cancer) in all recipients of first organ transplantation (1980-2007, restricting to those with known CMV sero-status). The recipients were divided into three groups based on CMV IgG sero-status: CMV exposure before transplant (group 1), exposure at transplant from CMV positive donor (group 2) and CMV-naÏve (group 3). Kaplan-Meier estimate, log rank test and Cox regression were used to assess the cancer incidence.

A total of 22464 recipients were studied including 13218 (59%) kidney, 4814 (21%) liver, 2686 (12%) heart and 1746 (8%) lung recipients. Of these 12423 (55%) were CMV-exposed prior to transplant (group 1), 4520 (20%) received a CMV positive graft (group 2) and 5521 (25%) were not exposed to CMV (group 3). The unadjusted incidence rates of cancer at 10 years after transplantation in groups 1, 2 and 3 were 8.9% (95% Confidence limits 8.3, 9.5), 7.0% (6.0, 7.9) and 6.4% (5.5, 7.2) respectively (p<0.001), however the age-gender adjusted hazard of cancer was not significantly different in the three groups (hazard ratio compared to group 1): group 2, 1.0 (0.8, 1.1) and group 3, 0.96 (0.8, 1.1), p=0.84. Cox regression analysis showed no significant difference between the three CMV groups, for the risk-adjusted hazard of developing any of the 21 types of cancers including cancer of anus, bladder, breast, cervix, colon, Kaposi’s sarcoma, kidney, lip, liver, leukaemia, lung, lymphoma, myeloma, oesophagus, oral cavity, ovary, pancreas, melanoma, stomach, thyroid or uterus.

From this large national data including all solid organ recipients, we conclude that the exposure to CMV before or at the time of transplantation does not significantly affect the incidence of post transplant cancer.

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