Ultrasound Method Linked With Improved Survival in Patients With CRC Liver Metastases

A new study published in Digestive and Liver Disease¹ found that intraoperative contrast-enhanced ultrasound could reduce the risk of intrahepatic recurrence in patients with colorectal cancer liver metastases (CRLM). This could benefit patients in terms of their hepatic recurrence-free survival (HRFS).

Colorectal cancer (CRC) is the second leading cause of cancer deaths in the world² and has the ability to metastasize. The liver is among the more common areas of metastasis, with up to 20% of patients first diagnosed with CRC also diagnosed with CRLM and an additional 40% to 50% likely to develop CRLM after resection. Hepatectomy is a method of treating CRLM, with intraoperative ultrasound a major tool used to identify and stage tumors. Contrast-enhanced intraoperative ultrasound (CE-IOUS) could help in detecting tumors that have disappeared from view, the researchers noted. This study aimed to focus on survival outcomes and how they could be influenced by CE-IOUS performed on patients diagnosed with unresectable CRLM who had a liver metastasis resection.

Patients were eligible if they were diagnosed with unresectable CRLM and underwent a liver metastasis resection. Patients were included if they were 18 years or older, had histopathologically confirmed CRC, had abdominal CT and MRI for their liver conducted at the center before chemotherapy, and if all CRLMs were capable of microwave ablation or surgical resection. Patients were excluded if they had positive margins after liver resection, had an excessive number of hepatic metastases, had an allergy to eggs, were pregnant, had previous local ablation or surgery, had no neoadjuvant or adjuvant chemotherapy, or had no imaging either before chemotherapy or at follow-up.

Contrast-enhanced intraoperative ultrasound could help increase recurrence-free survival rates | Image credit: Orawan - stock.adobe.com

All participants had CT or MRI before chemotherapy and surgery. All patients also had open surgical resection for their liver metastatic tumors, wherein the surgeons located the tumors first by sight and touch before using IOUS to confirm tumor stage and locate hidden hepatic metastatic sites. All liver nodules were included in the analysis if they were identified by IOUS, CE-IOUS, or other preoperative imaging. Recurrence after hepatectomy for CRLM was the primary endpoint of the study. The day of liver surgery to the day of liver recurrence was defined as the HRFS.

There were 130 patients included in this study, of whom 59.8% were male, 51.5% received IOUS only (IOUS group), and 48.5% received both IOUS and CE-IOUS (CE-IOUS group). The patients in the IOUS group had a mean (SD) age of 57.1 (10.8) years compared with 55.5 (12.2) years in the CE-IOUS group. Baseline characteristics of the patients were comparable between the 2 groups, including primary tumor location, gender, and positive primary lymph node metastasis.

When detecting CRLMs identified before the operation, the IOUS group had an 89.8% detection rate compared with 100% for the CE-IOUS group. Disappearing liver metastases were identified in 60 of the 63 patients in the CE-IOUS group. CE-IOUS was also able to detect 68.3% of CRLMs compared with IOUS that detected 51.7%. IOUS missed 4 CRLMs in 3 patients which led to recurrence; these CRLMs were all detected by CE-IOUS.

The overall group had a median (IQR) follow-up time of 24.0 months (21.6-29.9); the IOUS group had a follow-up of 39.2 (34.68-42.4) months and the CE-IOUS group had a follow-up of 18.5 (16.8-20.7). The IOUS group had a death rate of 26.9% compared with 6.3% in the CE-IOUS group. The difference in overall survival between the 2 groups was not significant. Early hepatic recurrence was found in 19.4% of the CE-IOUS group compared with 31.3% of the IOUS group.

HRFS was improved in patients who underwent CE-IOUS compared with IOUS only, with the HRFS rates at 6 and 12 months being 85% and 63% in the CE-IOUS group compared with 67% and 49% in the IOUS group.

There were some limitations to this study. The relationship between intraoperative nodules and prognosis was not explored. Matching of metastasis location and number on imaging was not possible due to the retrospective nature of the study. Recurrence was not explored in depth and only focused on intrahepatic recurrence. The follow-up period was shorter, and a longer follow-up period could be needed in the future to corroborate the findings. There was potential selection bias and the 2 study groups had operation times that differed. The number of included cases was limited due to strict inclusion criteria.

The researchers concluded that CE-IOUS can help to reduce the risk of intrahepatic recurrence in patients with CRLM as it is able to help detect lingering nodules and tumors in the area. The CE-IOUS can also help improve the HRFS of these individuals overall.

References

1. Li H, Shi M, Long X, et al. Contrast-enhanced intraoperative ultrasound improved hepatic recurrence-free survival in initially unresectable colorectal cancer liver metastases. Dig Liver Dis. 2024:S1590-8658(24)01009-0. doi:10.1016/j.dld.2024.09.009
2. Colorectal cancer: key facts. World Health Organization. July 11, 2023. Accessed September 30, 2024. https://www.who.int/news-room/fact-sheets/detail/colorectal-cancer