By Dr Ananya Mandal, MD
Metastasis denotes distant spread of cancer from the primary organ. Treatment of any form of cancer is dependent on whether or not it has spread to distant organs. If the cancer spreads to other tissues and organs, it may decrease a patient's likelihood of survival. Cancer of the testes and thyroid however when metastasized may still be curable.
When cancer has metastasized, it may be treated with radiation therapy, surgery, chemotherapy, biological therapy, hormonal therapy or a combination of these. The choice of treatment generally depends on factors like:
- type of primary cancer
- size and location of the metastasis or secondary tumor
- general health and age of the patient
- types of treatments offered previously and their response and/or resistance in the patient
- patient’s personal choice
Types of treatment for metastatic cancer
There are many effective treatments for metastatic cancer. These treatments fall into three main types:
- Whole body treatment – this includes chemotherapy or anti-cancer medication that can reach all places of the body and radiation therapy
- Local treatment for secondary tumor alone – this includes localized surgery and removal of the tumor or localized radiation therapy on the secondary tumor alone
- Pain relief – this therapy is also called palliative therapy and is reserved for advanced cases of metastasis
Treatment of liver, lung and bone metastasis
Several treatment options are available for patients with metastases. These depend on the location of the primary cancer, the number and size of tumors, and the patient's general health.
Liver metastasis usually begins in a colon cancer in most cases. Cancers that commonly spread to the lungs include:
Almost all types of cancer have the potential to spread to the lungs. Bones are the third most common location where cancer cells spread and metastasize. Spine and ribs along with long bones are common sites for metastasis.
Surgery to remove secondary tumors
This is given in combination with chemotherapy. Liver surgery may also be performed using laparoscopic surgery techniques. Surgery may be used to remove the affected tumor in lungs or in the bone. When spine is affected the vertebrae may undergo vertebroplasty.
Several anticancer drugs like oxaliplatin and irinotecan are used in liver metastasis. Chemotherapy may be delivered through intravenous infusion or directly to the affected region with a procedure called hepatic arterial infusion. This is called Hepatic Arterial Infusion (HAI) Chemotherapy.
These target the cancer cells alone. They help by cutting off the cancer cells’ blood supply and kill the tumors. These are called anti-angiogenesis agents. These include bevacuzimab or Avastin. Another type of drug are the Epidermal Growth Factor Receptor (EGFR) Inhibitors. These drugs block epidermal growth factor receptor, a protein that may contribute to the progression of colorectal cancer. These include cetuximab or panitumumab. Biologic therapy is now used in combination with many chemotherapy drugs to improve the effectiveness of treatment.
This is commonly used in endocrine cancers like breast cancer, ovarian, testicular, prostate and uterine cancers that have metastasized to other parts of the body.
Those who cannot undergo surgery may need image guided therapies. Image-guided therapies use imaging techniques such as CT, ultrasound, x-ray, and MRI to guide the delivery of treatments directly to the tumor site. Image-guided therapies may be used alone along with chemotherapy. In most cases, these procedures are performed by interventional radiologists in the outpatient department or with a hospital stay.
This therapy helps to kill the secondary tumor with heat or cold. There are currently three types of thermal ablation, including radiofrequency ablation, which uses radiowaves to heat and kill the tumor. There is also microwave ablation, which uses microwaves to heat tumor cells and cryoablation, which freezes the tumor. Radiofrequency ablation, cryoablation are commonly used in bone metastasis as well.
In this a catheter is placed in the liver artery and a dye is injected to locate the tumor. Specially designed beads containing radioactive material are then inserted into the catheter. These deliver drugs to the tumor.
This is used in some cases to control metastases that cannot be surgically removed or are too large to be treated effectively with ablation. Another method is by using stereotactic body radiation therapy that uses highly focused radiation field to deliver greater doses of radiation in fewer treatments. Stereotactic radiotherapy is used commonly in brain metastasis and lung metastasis.
Reviewed by April Cashin-Garbutt, BA Hons (Cantab)