Malignant Pelvic Tumors Involving the Sacrum: Surgical Approaches and Procedures Based on a New Classification

Objective: To introduce a new classification of Enneking type IV pelvic tumors involving the sacrum and a corresponding system of standardized surgical approaches and procedures for resection of such tumors, and to investigate the feasibility and therapeutic effect of the new system.

Methods: Data on 59 patients treated between February 2003 and February 2013 by standardized surgical approaches and procedures were retrospectively reviewed. The study subjects comprised 28 male and 31 female patients with a mean age at diagnosis of 36 years (range, 2-72 years). There are four subtypes in the new classification: (i) subtype IVa, neoplasms invading the ipsilateral sacral wing; (ii) subtype IVb, neoplasms invading the ipsilateral sacral foramina; (iii) subtype IVc, neoplasms invading the contralateral sacral foramina; and (iv) subtype IVd, neoplasms invading the whole of the sacrum. Standardized surgical approaches and procedures were devised for en-bloc resection for each subtype with adequate margins.

Results: Adequate margins were achieved in 43/59 patients (72.9%). The mean operation time was 5.0 h and the mean intraoperative blood loss 2157 mL. At the final follow-up, 27/53 patients (50.9%) who had been followed up were alive and in complete remission. The mean Musculoskeletal Tumor Society 93 score was 17.4 (58%) of a possible 30 points. The mean functional score for patients who had undergone a pelvic zone II resection was 15.2, compared with 19.0 for those with an intact pelvic zone II.

Conclusions: The proposed standardized protocols should help orthopaedic surgeons to achieve adequate margins, manage risk, achieve better oncologic and functional outcomes, and minimize perioperative complications when treating massive pelvic tumors involving the sacrum.