How does Colon Cancer spread to Liver?
As you can see in the figure, the venous drainage from most of the part of colon, ultimately pass through the liver. So liver is the most common site for the distant spread of the tumor from colon.
As you can see in this figure, the tumor in the right side of colon has spread to the liver. In this figure, a left sided tumor has spread to the liver.
Treatment of Colon Cancer that has spread to Liver
When colon cancer spreads to liver, it is called as stage 4 disease. The treatment for most cases of stage 4 cancers is generally palliative, ie, with chemotherapy, targeted therapy and/or immunotherapy. Radiation therapy and/or surgery may also be done sometimes for symptom relief.
In some cases of metastasis to liver, when the disease involves only a certain part of liver, surgery maybe possible. So, if initially the metastasis involves a large part of liver. But after giving chemotherapy it regresses to a small part, surgery may be tried.
The final decision to do surgery or not is taken by the oncologist on an individual patient basis, after assessing the exact pattern of liver involvement by the tumor, performance status of the patient along with other factors.
Role of Ablation or Embolization for Liver Metastasis
These techniques also are used when liver metastasis are limited to a small part that can be subjected safely and effectively to such modalities.
- Embolization is a process in which liver metastasis are addressed by injecting certain chemicals into the hepatic artery.
- It may be called radioembolization, chemoembolization or arterial embolization depending upon the type of substance used for the procedure.
- In arterial embolization, inert particles are used, whereas, particles are loaded with drugs in chemoembolization, and with radioactive substances in radioembolization). This technique is mainly used for destroying liver metastasis, if patient is a suitable candidate for the same.
- Similarly, Ablation is a technique in which tumor is destroyed without actual removal from the body.
- This technique is mainly used for destroying liver metastasis, if patient is a suitable candidate for the same.
- It may be called radiofrequency ablation, cryoablation, microwave ablation or percutaneous ethanol injection depending upon the technique.
- High-energy radio waves are utilized in radiofrequency ablation (RFA), microwaves are used in microwave ablation (MWA) technique, while very cold gases are used in cryoablation to destroy tumors.
- Sometimes, an ethanol injection given directly into the tumor tissue can be used to kill tumor cells. Imaging techniques are utilized along with these ablation techniques to accurately locate the target tumors.
Role of Radiation Therapy
In some cases radiation therapy may also be used in cases of limited metastasis of colon cancer to liver. The techniques that may be used in such cases are SBRT (stereotactic body radiotherapy) or TARE (transarterial radioembolization).
These techniques help in selective destruction of liver metastatic sites. But as discussed above, these are also useful only when disease is localied to a small part of liver.