Metastatic liver tumors, also known as secondary liver tumors, include metastatic liver cancer and metastatic liver sarcoma. The primary tumors are most commonly (57%) colorectal cancer, gastric cancer, pancreatic cancer, and gastrointestinal leiomyosarcomas. Other primary tumors, such as lung cancer, breast cancer, kidney cancer, cervical cancer, ovarian cancer, prostate cancer, and head and neck tumors, can also result in liver metastases.
Classification
Based on the temporal relationship between the primary tumor and the metastatic liver tumor, three types are identified:
- Early-Onset Type: The metastatic liver tumor is identified first, and the primary tumor is located later.
- Synchronous Type: The primary tumor and the metastatic liver tumor are detected simultaneously.
- Delayed-Onset Type: Liver metastases occur months or years after the primary tumor is diagnosed or surgically removed.
Clinical Manifestations and Diagnosis
Small metastatic liver tumors are typically asymptomatic and are often discovered during imaging examinations. As the tumors enlarge, symptoms such as discomfort or dull pain in the upper abdomen or liver region may occur. In advanced stages, symptoms like fatigue, fever, and weight loss may develop, and patients in late stages may present with anemia, jaundice, and ascites. Physical examination may reveal an enlarged liver, and in some cases, hard cancerous nodules may be palpable.
Imaging techniques such as ultrasonography, CT, MRI, and PET are of significant value in diagnosis. Tumor markers also aid in diagnosis. AFP elevation is uncommon; however, markers like CEA, CA19-9, and CA125 have diagnostic value for liver metastases originating from cancers of the digestive system, lung, and ovaries.
Treatment
For solitary metastatic liver tumors, liver resection is the most effective treatment method. For multiple metastatic liver tumors, there is ongoing debate over the feasibility of liver resection. Some studies have reported positive outcomes after single-stage resection of up to five metastatic liver tumors. The surgical principle involves complete tumor removal while preserving as much healthy liver tissue as possible.
In synchronous cases, if the patient’s general condition allows, simultaneous resection of both the primary tumor and the metastatic tumor may be performed. For patients with metastatic liver cancer unsuitable for surgical resection, or when unresectability is discovered intraoperatively, local treatment options are determined based on the patient’s overall condition and the characteristics of the primary tumor. These options include regional perfusion chemotherapy, microwave ablation, radiofrequency ablation, cryotherapy, and radiotherapy. Systemic treatment options include chemotherapy and immunotherapy combined with targeted therapies. In some cases, treatment may lead to tumor shrinkage or a reduction in the number of tumors, thereby prolonging survival.
Prognosis
The prognosis depends on several factors, including the nature of the primary cancer, the timing of liver metastases, the severity of the primary and metastatic cancers at the time of diagnosis, the tumor's sensitivity to drug therapy, and individual patient factors. Overall, the five-year survival rate after surgical resection of metastatic liver cancer ranges from 25% to 46%.