According to statistics, more than 800,000 people die from liver cancer every year in the world. China accounts for more than half of the world's liver cancer patients, making it the second leading cause of death among cancer patients in China. In addition to primary liver cancer, the liver is one of the common sites of metastases. The traditional treatment is still surgical resection. However, most patients are diagnosed in the middle or late stages, or are inoperable due to age or other diseases. Only a few people have the opportunity to undergo surgery or receive liver transplantation.
Tumor ablation is one of the important treatment methods for multidisciplinary comprehensive treatment of liver cancer. It boasts of small incision, fast recovery, repeatability, wide indications, and precise. It can not only cure early-stage liver cancer, but also has good effects on mid- and late-stage liver cancer. Among all the ablations, cryoablation is recommended in the 2010 NCCN liver cancer treatment guidelines. Recently, Fuda’s Vice President Liang Bing shared about the cryoablation of liver tumors and the prevention of complications.
As a minimally invasive treatment technology, cryoablation uses ultra-low temperature to form ice crystals within tumor cells. The alternation of freezing and warming causes cell wall rupture and damage, small blood vessel obstruction, micro-thrombosis, etc., causing tissue ischemia and hypoxia, leading the target tumor cells to dead. Several randomized controlled experiments have shown that surgical resection and local ablation have comparable long-term outcomes for small liver cancers, and that supplementation with ablation or salvage surgery can effectively improve patients' overall survival.
For those who refuse surgery for primary small liver cancer, the elderly with cardiopulmonary insufficiency or not suitable for surgery, those with severe hepatitis, cirrhosis, poor liver function, those who cannot tolerate surgical resection due to huge or multiple masses or recurrences that are difficult to surgically remove, those who with residual liver cancer or tumor residue at the tip after surgery, cryoablation is the option.
In addition, cryoablation can form different shape of ice balls by puncturing cryo-probes within the lesion and nearby tissue structures with different temperatures, which can avoid irreversible damage to the gallbladder, intestines and diaphragm. Also, it is safer for unusual parts such as those adjacent to the liver surface, diaphragm, gallbladder, liver hilus, etc.
Complications of liver puncture ablation are a prominent clinical issue, but adequate preoperative assessment and preparation, precise intraoperative guidance, meticulous puncture, reasonable needle insertion, and real-time intraoperative and postoperative monitoring can effectively avoid complications.
Main complications and treatments:
Fever
The incidence rate is about 25-30%. Usually occurs on the day or the next day of surgery, the body temperature is usually between 37.5 and 38.5 ℃, and can reach as high as 39.0 ℃. It usually lasts for 3 to 5 days and requires routine symptomatic treatment.
Pain
The incidence rate is about 10%. It often occurs on the day of surgery or 3-5 days after surgery. Mostly found in the upper abdomen after ablation close to the liver capsule.
Liver rupture and abdominal bleeding
The incidence of massive bleeding is about 1%. Injury to the liver or celiac arteries during the punctuation can lead to massive abdominal bleeding. Liver rupture is mostly caused by the rupture of the liver surface during the forming and rewarming process of the ice ball. If necessary, arterial intervention or laparotomy is required to stop the bleeding.
Prevention:
Platelets>70×109/L, PT prolongation <3 seconds, APTT prolongation <10 seconds, vitinogen>1.5g;
If hypersplenism, splenic embolization can be performed;
Platelets are 50~70×109/L, thermal ablation, Nanoknife, etc. can be performed.
Pneumothorax and hemothorax
For patients with lesions near the top of the right diaphragm, the puncture operation may damage the diaphragm, intercostal vessels and adjacent lung tissue, which can lead to pneumothorax and hemothorax. If necessary, thoracentesis and tube drainage are required, and interventional embolization or thoracotomy is required for massive bleeding. Using ultrasound can avoid the great blood vessels of the liver, but it is easy to damage the intercostal arteries.
Chills
The incidence rate is about 20%, and it usually appears during to 2 hours after the operation. Use thermal blanket can reduce the occurrence. Phenergan and tramadol can be used as symptomatic treatment.
Arrhythmia
It often happens during surgery and manifests as bradycardia and premature ventricular contractions, mainly caused by low temperature and puncture operation stimulating the vagus nerve. Intravenous anesthesia is safer than simple local anesthesia. When the tumor is close to the cardiac, the ablation gas volume should be controlled or water isolation technology should be used.
Platelets decrease
Platelets might dropped to half of the preoperative level 2 days after surgery, gradually increased after one week, and returned to normal in the second week; platelet transfusion can be considered when the platelet count is lower than 30×109/L. (Factors affecting platelets: preoperative platelet absolute value, ablation time, ablation range.)
Cold shock
Multiple organ failure severe blood coagulation abnormalities, and disseminated intravascular coagulation (DIC) may occasionally happens in the cases of wide-range cryoablation (ARDS, liver failure, renal failure, shock); the key to preventing cold shock is to keep warm during and after surgery, using a warm blanket during surgery can effectively prevent the occurrence of cold shock. For larger lesions, cryoablation can be performed in stages.
Renal insufficiency (oncolytic syndrome)
The cause is thought to be acute tubular necrosis caused by myoglobinuria. A large amount of myoglobin is deposited in the renal tubules, which can cause kidney damage and, in severe cases, acute renal failure.
Prevention: Postoperative fluid rehydration >2000ml, appropriate hydration and diuresis, and daily urinate more than 2000ml three days after surgery.
Liver insufficiency
Transaminases and bilirubin increased within one week after surgery and gradually returned to normal; liver function need to be correctly assessed before surgery and liver-protective treatment need to be provided after surgery.
The diversity and complexity of the mechanisms of liver cancer have brought great difficulties to clinical treatment, and it is difficult for a single treatment method to achieve good results. In recent years, combined methods can be used to treat intermediate and advanced liver cancer that cannot be surgically removed. If the mass is large or invades nearby important structures (gallbladder, portal vein, main branches of bile ducts, diaphragm, etc.), in order to reduce complications and ensure the safety of treatment, radiotherapy can be used if cryotherapy cannot completely cover the lesion. For larger lesions with rich blood supply, vascular interventional therapy can be performed first to reduce bleeding and clarify the scope of ablation.
Studies have found that cryoablation can not only control the primary tumor, but also induce specific or non-specific anti-tumor responses, producing "remote effect." With the emergence of new anti-tumor immunotherapies such as immune checkpoint inhibitors PD-1/PD-L1 and CAR-T in recent years, immunotherapy has become a new direction in tumor treatment. A large number of clinical applications have shown that the combination of cryoablation, radiotherapy, chemotherapy, and immunotherapy for liver cancer achevies positive effects. In addition, local cryotherapy for liver cancer can be combined with targeted therapy, antiviral therapy, traditional Chinese medicine therapy and other methods to consolidate the curative effect and prolong the patient's survival.