Surgical strategy for metastatic spinal tumors based on Spine Instability Neoplastic Score and patient-reported outcomes: JASA multicenter prospective study
Authors: Nakajima Hideaki , Watanabe Shuji , Honjoh Kazuya , Kubota Arisa , Shiratani Yuki , Suzuki Akinobu , Terai Hidetomi , Shimizu Takaki , Kakutani Kenichiro , Kanda Yutaro , Tominaga Hiroyuki , Kawamura Ichiro , Ishihara Masayuki , Paku Masaaki , Takahashi Yohei , Funayama Toru , Miura Kousei , Shirasawa Eiki , Inoue Hirokazu , Kimura Atsushi , Iimura Takuya , Moridaira Hiroshi , Akeda Koji , Takegami Norihiko , Nakanishi Kazuo , Sawada Hirokatsu , Matsumoto Koji , Funaba Masahiro , Suzuki Hidenori , Funao Haruki , Oshigiri Tsutomu , Hirai Takashi , Otsuki Bungo , Kobayakawa Kazu , Uotani Koji , Manabe Hiroaki , Tanishima Shinji , Hashimoto Ko , Iwai Chizuo , Yamabe Daisuke , Hiyama Akihiko , Seki Shoji , Goto Yuta , Miyazaki Masashi , Watanabe Kazuyuki , Nakamae Toshio , Kaito Takashi , Nakashima Hiroaki , Nagoshi Narihito , Kato Satoshi , Imagama Shiro , Watanabe Kota , Inoue Gen , Furuya Takeo 
Published: November 2024

OBJECTIVE
Instrumentation surgery in combination with radiotherapy (RT) is one of the key management strategies for patients with spinal metastases. However, the use of materials can affect the RT dose delivered to the tumor site and surrounding tissues, as well as hinder optimal postoperative tumor evaluation. The association of the preoperative Spine Instability Neoplastic Score (SINS) with the need for spinal stabilization and life expectancy are unclear. This multicenter prospective study aimed to investigate the current situation and make recommendations regarding the choice of surgical procedure based on the preoperative SINS and prospectively collected postoperative patient-reported outcomes (PROs).

METHODS
The study prospectively included 317 patients with spinal metastases who underwent palliative surgery and had a minimum follow-up period of 6 months. The survey items included SINS, patient background, and clinical data including surgical procedure, history of RT, prognosis, and PROs (i.e., the visual analog scale score, Faces Scale, Barthel Index, Vitality Index, and 5-level EQ-5D health survey) at baseline, and at 1 and 6 months after surgery. The association of preoperative SINS with life expectancy, PROs, and surgical procedures was examined using statistical analysis.

RESULTS
Preoperative SINS (three categories) had no association with life expectancy. All PROs evaluated in the study improved up to 6 months after surgery. Pain categories (visual analog scale score and/or Faces Scale) at baseline were correlated with preoperative SINS. As many as 90.9% of enrolled patients underwent fusion surgery, and even in SINS 0–6 cases, implants were used in 64.3% of patients. Postoperative RT was performed in 42.9% of the patients. However, prospective assessments of PROs showed no significant difference between surgical procedures (with and without fusion) in patients with SINS 0–9. In addition, no cases required conversion from noninstrumentation surgery to fusion surgery.

CONCLUSIONS
Although the choice of surgical procedure should be made on a case-by-case basis on the NOMS (neurological, oncological, mechanical, and systemic) framework, careful consideration is required to determine whether spinal stabilization is needed in patients with SINS ≤ 9, considering the patient’s background and the plan for postoperative adjuvant therapy.