Abstract 5113: Spontaneous tumors in aging colonies of C57BL/6J mice

Abstract The C57BL/6J inbred mouse strain is widely used to study the effects of aging. We have documented 51 spontaneous tumors (39 malignant and 12 benign) as part of a recent effort to establish large colonies of male and female C57BL/6J mice for aging research. Forty six of the tumors were diagnosed in mice submitted for histopathology from typical aging colonies maintained throughout a range of ages (6-18 months) that roughly correspond to 30 - 56 years of age in humans; the remaining cases were from much smaller cohorts aged past 18 months. Sarcomas represented the largest category of malignant tumors (20/51). There were 6 cases (5 male, 1 female) of hemangiosarcoma (4 on the neck, 1 on the liver, and 1 on the ear) and 6 multicentric histocytic sarcomas (4 male, 2 female). Four cases (1 male, 3 female) of rhabdomyosarcoma (2 on the head, 2 on the leg) were also seen. The remaining sarcoma diagnoses included one osteosarcoma (female; leg), one chondrosarcoma (male; ear), and two sarcomas not otherwise specified (both female; one leg, one lateral abdomen). Hematological malignancies constituted the second largest category (9/51), including 7 multicentric lymphomas (3 male, 4 female), a uterine lymphoma, and a multicentric plasma cell tumor (1 male). The four skin malignancies included two melanomas (male: head; female: tail/anus) and two squamous cell carcinomas (male: jaw; female: leg). Three mammary cancers were observed in females, including an adenoacanthoma and two adenocarcinomas, one of which had lung metastases. An ovarian dysgerminoma was the only germ cell tumor documented. The Harderian gland (a lacrimal duct of the eye) was the site of two carcinomas (male) and six adenomas (5 male, 1 female). Other benign tumors included a tail fibroma (male), two pulmonary adenomas (1 male, 1 female), one mammary fibroadenoma (female), a myoepithelioma of the leg (female), and a keratoacanthoma of the paw (female). Tumor incidence was very low overall, representing <0.1% of the mice present on an average week during the typical range of ages (6-18 months) in the aging colonies. Overall, the median age of diagnosis was 239 days for females and 427 days for males. These results should help to define the spectrum of tumors that develop in colonies of C57BL/6J mice that approximately correspond in age to middle-aged humans. Citation Format: Andrew Schile, Stephanie Dion, Denise Imai-Leonard, Rosalinda Doty. Spontaneous tumors in aging colonies of C57BL/6J mice [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5113.