Metastatic colorectal cancer
Colorectal cancer refers to cancers that originate in the glandular cells of the lining of the colon or rectum. In Finland, colorectal cancer is the second most common cancer in both women and men, following breast and prostate cancers. Western lifestyles have been linked to an increased risk of colorectal cancer, and its incidence is rising in Western countries. The curative treatment is surgery, combined with adjuvant therapy using either systemic medical therapy or a combination of medical and radiation therapy. Some cases recur either locally or as metastatic disease.
At the time of diagnosis, about one-quarter of cases are found to have spread to other organs. Metastatic sites are most commonly located in the liver, lungs, and lymph nodes. Some patients with metastatic disease can still be cured. Furthermore, the outcomes for treatments aimed at slowing down the progression of the disease (non-curative/palliative care) are currently good. Treatment is always planned collaboratively between the doctor and the patient.
- Advanced colorectal cancer means that the cancer initiated in the bowel has spread from the original tumor to other parts of the body. Metastases are most commonly found in the liver, lungs, and lymph nodes. Some cases of advanced cancer can still be cured, and treatments can also slow down the progression of the disease.
Treatment of advanced colorectal cancer
RAS gene testing helps select the most suitable treatment
When planning treatment for advanced colorectal cancer, the cancer tumor’s DNA is analyzed to look for genetic changes, known as mutations. One of the most important tests is the RAS gene test, which detects mutations in more than half of all patients. In cases where a RAS gene mutation is present, certain biological drugs cannot be used. Conversely, in non-mutated cases—referred to as “wild-type” cancer—these targeted drugs can be utilized and are highly effective. Therefore, RAS gene testing is essential when determining treatment options.
Together with your treating physician, the best treatment option will be selected for you at different stages of the disease. Your doctor will provide you with more information if needed.
The video below explains RAS gene testing and its significance in the treatment of advanced colorectal cancer in more detail.
This text was written in collaboration with Raija Kallio, Specialist in Oncology and Radiotherapy, and Susanna Jonkka, Medical Scientific Liaison (Oncology) at Merck Oy.
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Surgical treatment of advanced colorectal cancer
At the time of diagnosis, 20–25% of colorectal cancer patients are found to have distant metastases. An equal proportion of patients develop metastases during later stages of the disease. If the metastases are confined only to the liver, lungs, peritoneum, ovaries, etc., and their number and location are suitable, surgery aimed at a complete cure may be possible.
When are metastases resectable (operable)?
The patient’s overall health and performance status must be reasonably good to withstand metastatic surgery. In addition, the feasibility of the operation depends on the size, number, and location of the metastases.
Surgery is considered beneficial for the patient when all tumor tissue can be completely removed (resected). The fewer metastases there are, the more frequently surgery can be performed. For example, if the number of liver metastases exceeds five, surgery is rarely possible. This is because too little functioning liver tissue would remain after the operation.
On the other hand, even a large number of metastases can be removed if their location is favorable. At the time metastases are detected, approximately 10–25% of patients are candidates for liver surgery, 4–15% for the removal of lung metastases, and individual patients for the removal of other metastases.
Prognosis after surgery
The prognosis after surgery is influenced by several factors, such as the size and number of the metastases, the so-called healthy tissue margin (clear margin), and the stage of the colorectal cancer. If there has been only a single metastasis, the 5-year survival rate after surgery can be over 70%. The corresponding survival rate is 30–50% if there have been multiple metastases.
Thermal ablation (Thermoablation)
Thermal ablation (“heat treatment”) can be used to destroy a single metastasis. Thermal ablation is performed under ultrasound guidance by inserting a probe through the skin into the tumor. The probe heats its surroundings to approximately 70°C, causing permanent cellular damage and cell death.
The prognosis after ablation is slightly poorer than with surgical treatment. This method is used, for example, if there is a single, relatively small metastasis (under 3–4 cm) in the liver or lung, and the patient’s other medical conditions prevent surgical treatment.
SIRT therapy
SIRT stands for Selective Internal Radiation Therapy for liver tumors. In this treatment, microscopic particles containing the yttrium isotope are delivered through an arterial catheter directly into the liver metastases. The treatment is administered in collaboration with a radiologist, liver surgeon, oncologist, and medical physicist.
SIRT therapy is suitable for patients in good general health whose disease is primarily confined to the liver and whose metastases cannot be surgically removed. The treatment requires careful patient selection and planning to prevent potential complications.
See the HUS video below on the care pathway for patients undergoing liver surgery.