Dr. Chau Ka Foon
Renal transplantation was started in Hong Kong in 1969. Amongst 3794 renal transplants (male: 2237; female: 1557) there were 146 post-transplant malignancies (male: 73; female: 73) in 145 patients. One female patient had 2 malignancies. The overall incidence is 3.8%. When compared with the general population in Hong Kong, the relative risk of malignancy after renal transplant is 1.8 (male: 1.4; female 2.6). 18% of all malignancies developed within the first year and 53% within the first 5 years after transplant. The graft failure and patient death rate of transplanted patients with malignancy are 54.8% and 47.9% respectively. However, malignancy only accounts for 8.2% of all graft failure and 11.7% of all patient death, signifying malignancy is not the major cause of graft failure and patient death. When compared with patients with graft failure and died from other causes, patients with malignancy survived a longer post transplant period (graft survival: 7.3 years vs 4.7 years; patient survival: 7.1 years vs 5.8 years). When compared with the general population, the relative risk of death is 1.7 (male: 1.2; female 2.6). The commonest malignancies are PTLD (18%), Skin (8%), Liver (8%), Colon (7%) and Lung (7%). The relative risk is highest for Kaposi’s Sarcoma (>200), PTLD (12.3), Skin (6.0) and Thyroid (4.6). Relative risk is particularly high for carcinoma of kidney in male (RR 8.0) and carcinoma of bladder and cervix in female (RR 15.9 and 7.3 respectively). Use of anti-thymocyte antibody or OKT3 is associated with higher chance of post-transplant malignancies.
Liver transplant was started in Hong Kong in 1991. 14 cases of post-transplant malignancies are identified (male: 12; female: 2), including 10 adults and 4 children. The overall incidence is 2.7% (male: 3.2%; female 1.3%). 50% of all cancers are PTLD, including all children. 3 children and 1 adult died for PTLD within 13 months. 2 other patients died from other cancers after 37 and 109 months respectively.
Heart transplant was started in 1992. Amongst 78 patients, 5 malignancies are identified, all in male patients. The overall incidence is 6.4% (male 8.1%). The overall relative risk is 4.3 (male 4.7). There is one PTLD, developed within 6 months post transplant. The other malignancies developed in long survivors (5.4 – 11.9 yr after transplant). There are 4 deaths, accounting for 20% of all deaths. The relative risk of death is 6.5 (male 6.2).
Lung transplant was started in 1995. Amongst 13 lung and heart-lung transplant, one 33 year old female patient developed PTLD over the legs 7 years after double lung transplant. It may be related to the augmentation of immunosuppressives for her deteriorating lung function. She died of septicaemia 5 months after diagnosis of PTLD.
Overall, the incidence of malignancy is much higher in the transplant patients than the general population. The transplant population in Hong Kong is a ‘young’ population. Most of the transplants, especially for liver, heart and lung transplants, were performed within the recent 10 years. The current post-transplant malignancies seen are mainly those related to immunosuppression. There is the emergence of the more common cancers within the renal transplant patients who have the longer post-transplant survival. The change of utilization of immunosuppressive agents may also affect the pattern of post-transplant malignancy in the future.