Spontaneous tumours in tree shrews (Tupaia belangeri): population studies.

In a necropsy series at the German Primate Centre, 63 of 1132 tree shrews were found to have tumours. The youngest affected animal was < 6 months old, but the incidence of tumours increased strikingly beyond 2 years of age; of 17 animals aged > 8 years, no less than 14 (82.4%) were affected. The sites of neoplasia were the genital system (22 cases), haematopoietic system (18 cases of malignant lymphoma, many involving the digestive tract), lungs (14 cases), integument (five cases), digestive tract (three cases other than those with malignant lymphoma) and urinary bladder (one case).