Introduction: The impact of radiation on wound healing after metastatic spine surgery remains an active area of research. In patients undergoing metastatic spine surgery, we sought to (1) assess the relationship between preoperative and/or postoperative radiation on wound complications, and (2) evaluate the relationship between the timing of postoperative radiation and wound complications. Methods: A single-center, retrospective, cohort study of patients undergoing metastatic spine surgery was conducted from 2010 to 2021. The primary exposure variable was the use/timing of radiation. Radiation included both external beam radiotherapy (EBRT) and stereotactic body radiotherapy (SBRT). Patients were trichotomized into the following groups: (1) preoperative radiation only, (2) postoperative radiation only, and (3) no radiation. The primary outcome variable was wound complications, which was defined as dehiscence requiring reoperation, infection requiring antibiotics, or infection requiring surgical debridement. Multivariable logistic/linear regression controlled for age, tumor size, primary organ of origin, and the presence of other organ metastases. Results: A total of 207 patients underwent surgery for extradural spinal metastasis. Participants were divided into three groups: preoperative RT only (N = 29), postoperative RT only (N = 91), and no RT (N = 178). Patients who received postoperative RT only and no RT were significantly older than patients who received preoperative RT only (p = 0.009) and were less likely to be white (p < 0.001). No other significant differences were found in basic demographics, tumor characteristics, or intraoperative variables. Wound-related complications occurred in two (6.9%) patients with preoperative RT only, four patients (4.4%) in postoperative RT only, and 11 (6.2%) patients with no RT, with no significant difference among the three groups (p = 0.802). No significant difference was found in wound-related complications, reoperation, and time to wound complications between patients with preoperative RT only and no RT, and between postoperative RT only and no RT (p > 0.05). Among the postoperative-RT-only group, no difference in wound complications was seen between those receiving SBRT (5.6%) and EBRT (4.1%) (p > 0.999). However, patients who received preoperative RT only had a longer time to wound complications in comparison to those who received postoperative RT only (43.5 +/- 6.3 vs. 19.7 +/- 3.8, p = 0.004). Regarding timing of postoperative RT, the mean (SD) time to RT was 28.7 +/- 10.0 days, with a median of 28.7 (21-38) days. No significant difference was found in time to postoperative RT between patients with and without wound complications (32.9 +/- 12.3 vs. 29.0 +/- 9.7 days, p = 0.391). Conclusion: In patients undergoing metastatic spine surgery, a history of previous RT or postoperative RT did not significantly affect wound complications. However, those with previous RT prior to surgery had a longer time to wound complications than patients undergoing postoperative RT only. Moreover, timing of RT had no impact on wound complications, indicating that earlier radiation may be safely employed to optimize tumor control without fear of compromising wound healing.
