As the third leading cause of new cancer diagnoses as well as deaths each year in the United States, the rate of colorectal cancer continues to rise, predominately attributed to the increase in occurrence amongst people under the age of 50.
Just as alarming is the downstream rise in the incidence of colorectal liver metastases, the most common site of growth outside of the primary cancer site.
Approximately 30-50% of all patients with colorectal cancer will develop liver metastases.
In many types of cancers, once the disease has spread outside of the primary organ of origin, this is considered incurable. However, due to the unique biology and advances in multimodal management of colorectal liver metastases, this does not follow traditional oncology patterns, as long-term survival and disease clearance is achievable.
How does colorectal liver metastases present?
Dr. Brent Xia
Due to the liver’s functional reserve and capacity, the majority of patients are asymptomatic and liver metastases are detected either incidentally (imaging performed for other medical reasons) or on staging workup for newly diagnosed colorectal cancer. Presentation of colorectal liver metastases is categorized as synchronous or metachronous. Synchronous lesions, which constitutes 20% of all lesions, present either at the time or within 6 months of colorectal cancer diagnosis. Metachronous lesions are detected greater than six months after initial colorectal cancer diagnosis.
What are risk factors for colorectal liver metastases?
Higher initial stage (tumor thickness and depth of invasion) of colorectal cancer at diagnosis, including lymph node involvement and obstruction or perforation from tumor, increases the risk of developing colorectal liver metastases. Colorectal cancer screening is crucial towards early detection and yields the best results and treatment options. After curative resection of colorectal cancer, surveillance with exams, tumor markers and imaging are necessary.
What are the different treatment approaches for colorectal liver metastases?
Based on robust data from clinical trials as well as retrospective and prospective series (Engstrand et al):
• Patients who receive no oncologic treatment and only best supportive care/palliation have a median overall survival of 4-15 months, with a 5-year survival rate <2%. • Those who receive best available chemotherapy only have slightly improved median overall survival of 15-25 months and 5-year survival rate <11%. • Patients who receive multimodal therapy that includes systemic chemotherapy as well as surgical resection have a median overall survival of 50+ months and 5-year overall survival of 60%. This has more than doubled from 20 years ago thanks to improvements in the efficacy of systemic therapy as well as innovations in liver surgery. Who treats colorectal liver metastases?
Due to its aggressive nature, multimodal therapy is needed. Colorectal liver metastases are treated in a multidisciplinary fashion by numerous collaborating providers – surgical oncologists, medical oncologists, radiation oncologists, radiologists and interventional radiologists. Discussions are conducted at tumor board conference in order to receive a consensus opinion.
What determines the treatment order, surgery versus chemotherapy first?
Numerous patient and clinical factors are taken into consideration when determining treatment sequencing. The biology of the cancer, in terms of its aggressiveness, also plays a major role in the decision-making process. For tumor amenable to resection in order to render the patient free of disease, options include up front surgery or neoadjuvant (treatment before surgery) chemotherapy.
Additionally, for synchronous colorectal liver metastases, options include resection of the colorectal cancer first, liver metastases first, or combined approach. Factors such as burden of each disease site and patient performance status are considered and discussed in a multidisciplinary fashion.
For patients with borderline resectable (high chance of leaving tumor behind with a positive margin) or unresectable disease, strategies to downsize the tumor involve use of systemic therapy and re-evaluation with imaging.
What does surgical resection of liver metastases entail?
The liver is functionally and anatomically divided into 2 lobes, the right and left lobes. Each lobe is then separated into 4 segments. The location and size of liver metastases dictate the surgical clearance needed. This may entail a right or left lobectomy, or even a parenchyma-sparing technique involving partial hepatectomies/segmentectomies. Depending on the tumor size and location, this can be achieved via open surgery or minimally invasive techniques.
To maintain adequate future liver remnant to perform its vital functions, at least 20% remaining liver volume is necessary in healthy individuals, and at least 30% in patients who received chemotherapy. In patients who do not meet these benchmarks, growth/hypertrophy of the future liver remnant can be achieved via a percutaneous technique called portal vein embolization, which is performed by interventional radiologists prior to surgery to condition the liver.
Dr. Brent Xia, MD, is a surgical oncologist – Gastrointestinal and Hepato-pancreato-biliary — at St. Elizabeth Cancer Center. He is a graduate of Thomas Jefferson Medical College in Philadelphia and completed his residency in general surgery at the University of Cincinnati. He was awarded a fellowship in Complex General Surgical Oncology at Moffitt Cancer Center in Tampa, FL. For this column he cites sources: Engstrand, J., Nilsson, H., Strömberg, C. et al. Colorectal cancer liver metastases – a population-based study on incidence, management and survival. BMC Cancer 18, 78 (2018).
