1. This retrospective cohort study comparing carbon ion radiotherapy (CIRT) versus en bloc resection to treat sacral chordomas demonstrated similar oncologic outcomes between cohorts with regards to overall survival, local recurrence, and distant metastasis
2. Both groups experienced similar rates of urinary retention; however, the CIRT cohort had a reduced risk of peripheral motor neuropathy compared to those who received en bloc resection.
Evidence Rating Level: 2 (Good)
Study Rundown: The primary treatment for sacral chordomas, which are aggressive, slow-growing, embryonic notochord tumours, is en bloc surgical resection with negative margins. Alternatively, carbon ion radiotherapy (CIRT) has shown itself to be promising, with similar oncologic outcome success to surgery, yet reduced treatment side-effects. Studies are lacking in comparing the differences in outcomes between surgery and CIRT. This retrospective cohort study investigated the clinical outcomes and treatment-related adverse events between CIRT and en bloc resection for sacral chordomas. Primarily, this study compared a CIRT cohort (188 participants from January 1, 1998, until February 28, 2013) to an en bloc surgical resection cohort (54 participants from April 1, 1994, until July 31, 2017); 10 national cancer database (NCDB) cohorts were also included for comparison and supplementary analysis. The primary outcome was overall survival for all cohorts. Peripheral neuropathy and urinary retention at the last follow-up were also examined among patients. Upon comparison of the CIRT cohort with the en bloc resection cohort, there were no significant differences in overall survival (odds ratio [OR]: 0.71 [95% CI: 0.25-2.06]; p= 0.53), local recurrence (OR: 0.88 [95% CI: 0.31-2.41]; p= 0.80), distant metastasis (OR: 1.44 [95% CI: 0.63-3.30]; p= 0.39), or urinary retention post-treatment (OR: 0.65 [95% CI: 0.26-1.57]; p= 0.34) . Notably, peripheral motor neuropathy was less likely in the CIRT cohort at the last follow-up (OR: 0.13 [95% CI: 0.04-0.40]). Compared to the NCDB cohorts receiving primary radiotherapy, median overall survival was significantly greater in the CIRT cohort (64.9 months [95% CI: 57.0-70.5] vs. 31.8 months [95% CI: 27.9-40.6]; p< 0.001). Overall, CIRT treatment for chordomas demonstrated promising oncologic outcomes with some reduced side effects compared to the current standard of en bloc resection. One limitation of this study, however, is its retrospective design and likely confounders which calls for the need for prospective studies to further examine the difference in outcomes between these treatments.
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