Final diagnosis
Liver metastases in a patient with rectal cancer.
Differential diagnosis
None.
Discussion
20-25 % of patients, who have an unknown metastatic disease at the time of their primary colon or rectum cancer surgery may have occult liver metastases. The median survival period for patients with liver metastases from colorectal carcinoma is 4-12 months from the time of diagnosis of the metastatic disease.
Many methods are available for detection of intrahepatic metastatic disease: a variety of CT and MR imaging methods, transabdominal, intraoperative, and laparoscopic sonography. The usefulness of many of these techniques may vary between institutions because of local bias, expertise, or both.
There are two means of treating metastatic liver cancer: systemic and local-regional treatment.
Contraindications to resection is the presence of extrahepatic nodal metastases and the inability to resect for cure.
20-25 % of the patients will be free from the disease 5 years after hepatic resection. Recurrence in the liver is most often away from the surgical margin. This confirms the suspicion, that many patients, who undergo resection, harbor microscopic metastases, which are not detectable with cross-sectional imaging.
In the majority of the patients colorectal metastases to the liver will not be resectable because of the diffuse nature of the disease. After more than 30 years of investigations, the fluoropyrimidines are still the only effective class of cytostatic drugs for colorectal cancer. Combinations with other cytostatic drugs have improved the response rate. However, remissions are not durable and the advantages of survival are not clinically significant.
The value of repeated resections is questionable and often technically impossible to perform. The purpose of interstitial therapy for hepatic metastatic disease is a cure. All patients considered for this therapy should meet the same or similar criteria as those used for surgical resection.
Cryosurgery is performed with a cryoscope placed in the center of the metastasis with intraoperative US guidance. Laser photo coagulation involves heating the tumor by using a low power laser light, delivered via small optic fibres. This is a percutaneous method that uses US guidance.
The energy for creating a necrosis in RF abalation is delivered to the tumor by means of a RF electrode, using a needle which is electrically insulated along all but the distal 1-4 cm of the shaft. This needle is positioned into the tumor using a percutanous approach under US guidance. As the energy reaches its electrical ground, ions agitate and energy is converted into heat, which kills cells by coagulation necrosis.
Results obtained up until today by these methods are promising. However, long term results are still missing, and randomised studies in comparison with liver resection have not been performed.