Colorectal Pulmonary Metastases: Pulmonary Metastasectomy or Stereotactic Radiotherapy?

SIMPLE SUMMARY: Patients with oligometastatic colorectal pulmonary metastases have similar overall survival after radical-intent stereotactic ablative radiotherapy or pulmonary metastasectomy. The local recurrence rate for patients after stereotactic radiotherapy with oligometastatic colorectal pulmonary metastases was 38% with long-term follow-up and 52% of these patients were able to undergo local salvage therapy. Even though all patients underwent local treatment for oligometastatic disease, 46% of patients from both groups would eventually develop polymetastatic conversion. The randomized controlled COPPER trial is currently being designed in the Netherlands and will randomize patients with lung-limited oligometastatic colorectal pulmonary metastases between stereotactic radiotherapy and metastasectomy. ABSTRACT: Background: Pulmonary metastasectomy and stereotactic ablative radiotherapy (SABR) are both guideline-recommended treatments for selected patients with oligometastatic colorectal pulmonary metastases. However, there is limited evidence comparing these local treatment modalities in similar patient groups. Methods: We retrospectively reviewed records of consecutive patients treated for colorectal pulmonary metastases with surgical metastasectomy or SABR from 2012 to 2019 at two Dutch referral hospitals that had different approaches toward the local treatment of colorectal pulmonary metastases, one preferring surgery, the other preferring SABR. Two comparable patient groups were identified based on tumor and treatment characteristics. Results: The metastasectomy group comprised 40 patients treated for 69 metastases, and the SABR group had 60 patients who were treated for 90 metastases. Median follow-up was 38 months (IQR: 26–67) in the surgery group and 46 months (IQR: 30–79) in the SABR group. Median OS was 58 months (CI: 20–94) in the metastasectomy group and 70 months (CI: 29–111) in the SABR group (p = 0.23). Five-year local recurrence-free survival (LRFS) was 44% after metastasectomy and 30% after SABR (p = 0.16). Median progression-free survival (PFS) was 15 months (CI: 3–26) in the metastasectomy group and 10 months (CI: 6–13) in the SABR group (p = 0.049). Local recurrence rate was 12.5/7.2% of patients/metastases respectively after metastasectomy and 38.3/31.1% after SABR (p < 0.001). Lower BED Gy(10) was correlated with an increased likelihood of recurrence (p = 0.025). Clavien Dindo grade III-V complication rates were 2.5% after metastasectomy and 0% after SABR (p = 0.22). Conclusion: In this retrospective cohort study, pulmonary metastasectomy and SABR had comparable overall survival, local recurrence-free survival, and complication rates, despite patients in the SABR group having a significantly lower progression-free survival and local control rate. These data would support a randomized controlled trial comparing surgery and SABR in operable patients with radically resectable colorectal pulmonary metastases.