Comparative Efficacy of Preoperative, Postoperative, and Perioperative Treatments for Resectable Colorectal Liver Metastases: A Network Meta-Analysis

Systemic Therapy and Its Surgical Implications in Patients with Resectable Liver Colorectal Cancer Metastases. A Report from the Western Canadian Gastrointestinal Cancer Consensus Conference

The Western Canadian Gastrointestinal Cancer Consensus Conference (WCGCCC) convened virtually on 4 November 2021. The WCGCCC is an interactive multi-disciplinary conference attended by health care professionals, including surgical, medical, and radiation oncologists; pathologists; radiologists; and allied health care professionals from across four Western Canadian provinces, British Columbia, Alberta, Saskatchewan, and Manitoba, who are involved in the care of patients with gastrointestinal cancer. They participated in presentation and discussion sessions for the purpose of developing recommendations on the role of systemic therapy and its optimal sequence in patients with resectable metastatic colorectal cancer.

Dosimetric Comparison of Intraoperative Radiotherapy and SRS for Liver Metastases

Purpose/Objectives

To perform a dosimetric comparison between kilovoltage intraoperative radiotherapy (IORT) and stereotactic radiosurgery (SRS) simulating both deep-inspiration breath-hold (DIBH) and free-breathing (FB) modalities for patients with liver metastases.

Methods/Materials

Diagnostic computed tomographies (CT) of patients carrying one or two lesions <4 cm and who underwent surgery were retrospectively screened and randomly selected for the study. For DIBH-SRS, a gross target volume (GTV) plus planning target volume (PTV) were delineated. For FB-SRS, a GTV plus an internal target volume (ITV) and PTV were defined. Accounting for the maximal GTV diameters, a modified GTV (GTV-IORT) was expanded circumferentially to simulate a resection cavity. The best suitable round-applicator size was thereafter selected. All treatment plans were calculated homogeneously to deliver 40 Gy. Doses delivered to organs at risk (OAR) and target volumes were compared for IORT vs. both SRS modalities.

Results

Eight patients encompassing 10 lesions were included in the study. The mean liver volume was 2,050.97 cm³ (SD, 650.82), and the mean GTV volume was 12.23 cm³ (SD, 12.62). As for target structures, GTV-IORT [19.44 cm³ (SD, 17.26)] were significantly smaller than both PTV DIBH-SRS [30.74 cm³ (SD, 24.64), p = 0.002] and PTV FB-SRS [75.82 cm³ (SD, 45.65), p = 0.002]. The median applicator size was 3 cm (1.5–4.5), and the mean IORT simulated delivery time was 45.45 min (SD, 19.88). All constraints were met in all modalities. Liver V_9.1 showed significantly smaller volumes with IORT [63.39 cm³ (SD, 35.67)] when compared to DIBH-SRS [150.12 cm³ (SD, 81.43), p = 0.002] or FB-SRS [306.13 cm³ (SD, 128.75), p = 0.002]. No other statistical or dosimetrically relevant difference was observed for stomach, spinal cord, or biliary tract. Mean IORT D₉₀ was 85.3% (SD, 6.05), whereas D₉₅ for DIBH-SRS and FB-SRS were 99.03% (SD, 1.71; p = 0.042) and 98.04% (SD, 3.46; p = 0.036), respectively.

Conclusion

Kilovoltage IORT bears the potential as novel add-on treatment for resectable liver metastases, significantly reducing healthy liver exposure to radiation in comparison to SRS. Prospective clinical evidence is required to confirm this hypothesis.

Efficacy of perioperative chemotherapy in resected colorectal liver metastasis: A systematic review and meta-analysis

BACKGROUND

Nearly half of patients with colorectal cancer develop liver metastases. Radical resection of colorectal liver metastases (CRLM) offers the best chance of cure, significantly improving 5-year survival. Recurrence of metastatic disease is common, occurring in 60 % or more of patients. Clinical equipoise exists regarding the role of perioperative chemotherapy in patients with resected CRLM. This investigation sought to clarify the efficacy of perioperative chemotherapy in patients that have undergone curative-intent resection of CRLM.

METHODS

A systematic review and meta-analysis was completed of randomized controlled trials (RCTs) comparing perioperative chemotherapy to surgery alone in patients with resected CRLM. MEDLINE (Ovid), EMBASE and Cochrane Central Register of Controlled Trials (CENTRAL) databases were searched, as well as abstracts from recent oncology conferences. A meta-analysis was performed pooling the hazard ratios for disease-free survival (DFS) and overall survival (OS), using a random-effects model.

RESULTS

A total of five, phase 3, open-label, RCTs were included resulting in a pooled analysis of 1119 of the total 1146 enrolled patients. 559 patients were randomized to perioperative chemotherapy and 560 to surgery alone. Pooled estimates demonstrated a statistically significant improvement in DFS (HR 0.71, 95 % CI: 0.61-0.82; p < 0.001) but not OS (HR 0.87, 95 % CI: 0.73-1.04; p = 0.136).

CONCLUSION

Perioperative chemotherapy in the setting of resected CRLM resulted in an improvement in DFS, however this did not translate into an OS benefit. Poor compliance to post-hepatectomy oxaliplatin-based chemotherapy regimens was identified. Further investigation into the optimal regimen and sequencing of perioperative chemotherapy is justified.