Systemic effects of the VX2 carcinoma on the osseous skeleton. A quantitative study of trabecular bone.

The skeleton of rabbits bearing the transplantable VX2 carcinoma has been studied by a combination of radiographic and histomorphometric techniques. It has previously been shown that this tumor produces and secretes large amounts of prostaglandin E2. In vivo experiments, as well as cell and organ culture studies, have led to the conclusion that the hyerpcalcemia observed in tumor-bearing rabbits is due to excessive secretion of prostaglandin E2 by the tumor and its subsequent action on bone throughout the organism. Our new findings reveal (1) no evidence of local invasion of bone by the VX2 tumor or osseous metastases; (2) radiographic evidence of generalized osteopenia; (3) histomorphometric documentation in trabecular bone of reduced volume density of bone matrix, consistent with increased resorption in trabecular bone at sites distant from tumor; and (4) a marked generalized reduction in surface density of osteoblastic layers, volume density of osteoid, osteoid seam thickness, and surface density of osteoid. These findings in trabecular bone of iliac crest and vertebra offer quantitative data in support of the conclusion that VX2 carcinoma affects skeletal metabolism systemically.