PURPOSE: Immunosuppression used in transplantation is associated with an increased incidence of various cancers. Although the incidence of colorectal cancer in transplant patients seems to be equal to nontransplant population, the effects of immunosuppression on patients who develop colorectal cancer are not well defined. The purpose of this study was to define the characteristics and survival patterns of transplant patients developing de novo colorectal cancer. METHODS: The Israel Penn International Transplant Tumor Registry was queried for patients with colorectal cancer. Analysis included patient demographics, age at transplantation and colorectal cancer diagnosis, tumor stage, and survival. Age and survival rates were compared to United States population-based colorectal cancer statistics using the National Cancer Institute Surveillance Epidemiology and End Results database. RESULTS: A total of 150 transplant patients with de novo colorectal cancer were identified: 93 kidney, 29 heart, 27 liver, and 1 lung. Mean age at transplantation was 53 years. Age at transplantation and colorectal cancer diagnosis was not significant for gender, race, or stage of disease. Compared to National Cancer Institute Surveillance Epidemiology and End Results database, transplantation patients had a younger mean age at colorectal cancer diagnosis (58 vs. 70 years; P < 0.001), and a worse five-year survival (overall, 44 vs. 62 percent, P < 0.001; Dukes A&B, 74 vs. 90 percent, P < 0.001; Dukes C, 20 vs. 66 percent, P < 0.001; and Dukes D, 0 vs. 9 percent, P = 0.08). CONCLUSIONS: Transplant patients develop colorectal cancer at a younger age and exhibit worse five-year survival rates than the general population. These data suggest that chronic immunosuppression results in a more aggressive tumor biology. Frequent posttransplantation colorectal cancer screening program may be warranted.