Sacral infiltration in pelvic sarcomas: joint infiltration analysis II.

The incidence and characteristics of sacral infiltration in pelvic sarcomas were analyzed. Fifty-one patients with a pelvic sarcoma (chondrosarcoma, 15 patients; Ewing's sarcoma, 23 patients; and osteosarcoma, 13 patients) abutting the sacroiliac joint had surgical treatment. Tumor infiltration into the sacrum was suspected based on preoperative images in 18 patients; 15 of 18 patients had histologic tumor invasion. There was a significant difference of median volume of sarcomas with and without infiltration. One of 23 Ewing's sarcomas, seven of 15 chondrosarcomas, and seven of 13 osteosarcomas penetrated the sacroiliac joint into the sacrum. Logistic regression test showed that diagnosis was the most important factor influencing sacral infiltration. Twelve tumors infiltrated through the posterior part of the joint, two tumors infiltrated through the anterior part, and one large tumor infiltrated through an unknown route. To obtain wide surgical margins, patients at risk (elderly, large tumor, or diagnosis of osteosarcoma or chondrosarcoma) for sacral involvement may require extended internal hemipelvectomy with the medial margin extending into the sacrum. High quality imaging studies should be used to assess the need for transarticular resection.