How Do I Choose the Best Pheochromocytoma Treatment?

Malignant pheochromocytoma is rare, only 0.005% to 0.1% seen at necropsy, 80% of tumors occur in the adrenal medulla, 15% outside the adrenal; 10% to 50% are malignant, slow and rare growth, MayoClinic group The study reported that its 5-year survival rate was 36%, and most died within 3 years after metastasis was found, with a poor prognosis.

Malignant pheochromocytoma

Introduction to malignant pheochromocytoma

Overview of malignant pheochromocytoma

Both malignant pheochromocytoma and pheochromocytoma secrete adrenaline and norepinephrine, so the clinical manifestations are hypertension and metabolic symptoms, and their diagnosis is also elevated in blood and urine catecholamine levels (normal 8-165ug / day). ), Antihypertensive drug inhibition test, CT scan, etc. 131I-MIBJ (Metaiodoben-zylguanidine) scan and so on.

Principles of treatment for malignant pheochromocytoma

(1) Surgical resection is the main method for the treatment of malignant pheochromocytoma. Recurrence and metastases should be removed as much as possible to reduce tumor burden and reduce symptoms, but blood pressure should be paid attention to before, during, and after surgery to avoid occurrence. Sudden death and other accidents.

(2) Radiotherapy for malignant pheochromocytoma is slightly sensitive to radiotherapy and can be used as appropriate.

(3) Radioisotope treatment The tumor is highly sensitive (85%) and specific (100%) to 131I-MIBG imaging. Therefore, a larger dose (200mCi in 5mg) is used to treat recurrent, metastatic malignant pheochromocytoma, but The curative effect is not satisfactory. For example, Feldman et al. (1984) reported that catecholamine levels decreased in only 5 of 12 cases and tumor shrinkage in only 2 cases.

(4) The effective rate of CTX + VCR + DTIC for chemotherapy of metastatic neuroblastoma is 80%, and this scheme is also effective for metastatic pheochromocytoma.

Malignant pheochromocytoma treatment

Surgical removal of pheochromocytoma is the most effective treatment, but surgery has certain risks. Squeezing the tumor during anesthesia and surgery can easily cause blood pressure fluctuations; tumors have abundant blood flow, are close to large blood vessels, and easily cause large amounts of bleeding. Therefore, the correct management before, during and after surgery is extremely important.

In patients with pheochromocytoma, due to the high secretion of theophylline, the blood vessels are in a contracted state for a long time. Although the blood pressure is high, the blood volume is often insufficient. Therefore, sufficient medication should be prepared before surgery to relax the blood vessels, reduce blood pressure, and expand blood volume. At present, phenoybenzamine, an alpha-adrenergic receptor blocker, is used in a variety of dosages, at a dose of 10 to 20 mg, 2 to 3 times a day for 2 to 6 weeks. Beta adrenergic receptor blocker propranolol 10mg, 2 to 3 times a day, taken about 1 week before surgery, can prevent tachycardia and cardiac rhythm disorders during surgery.

The choice of anesthesia methods and drugs should meet the following conditions: there should be no significant inhibition on the effectiveness of the heart pump; no increase in sympathetic excitability; favorable blood pressure control during surgery; after tumor resection, it is beneficial to restore blood volume and Maintain blood pressure. At present, more general anesthesia is advocated. Surgical incisions depend on the accuracy of diagnosis and localization and the size of the tumor. Most diagnostic abdominal exploration incisions are more secure.

The pre-prepared floating catheter (Swan-Ganz cardiac catheter) currently under development to monitor the pulmonary artery wedge pressure can accurately and reliably monitor the patient's heart pumping status and effectively maintain blood volume, and provide benefits for the successful completion of the operation. condition.

-methyltyrosine (-methyltyrosine) can block catecholamine synthesis. It can be used with benzylamine in patients who cannot be operated, but it is prone to drug resistance in long-term use.

Cases of malignant pheochromocytoma

Internal radionuclide irradiation for malignant pheochromocytoma and its metastases

principle

131I-MIBG is an anti-adrenal neuron agent, which can be taken up by all tumors with adrenal neurons, such as pheochromocytoma, neuroblastoma and other tumors, and can be concentrated in carcinoid and medullary thyroid carcinoma tissues. The radioactivity ratio of 131I-MIBG in tumor and liver can reach 680: 1, so it can be used for treatment. Malignant pheochromocytoma and its metastases are not sensitive to chemotherapy and radiation therapy, but large doses of 131I can be used. -MIBG treatment can make the absorbed dose of tumor reach tens of Gy (Gray), and such radiation dose can inhibit or destroy tumor tissue to achieve the purpose of treatment.

Indication

1. Patients cannot undergo surgery or chemotherapy, and radiotherapy fails.

2. Patients who are expected to survive more than 1 year.

3. Tumor lesions can ingest 131I-MIBG: 37MBq (1mCi) of 131I-MIBG can cause tumors to receive an absorbed dose of 0.2Gy (20rad).

4. Pain caused by bone metastases.

5. Patients with uncontrollable hypertension.

treatment method

First, the uptake rate and effective half-life of 131I-MIBG per gram of tissue were measured. The size of the tumor should be estimated by SPECT, CT, or B ultrasound to calculate the absorbed dose of the tumor. Generally, 200 Gy (20,000 rad) is required for each course of treatment. Three days before the treatment dose, Lugol's solution was started, 10 drops 3 times a day for 4 weeks after treatment. At present, it is advocated that the first dose should be 131I-MIBG of about 3700-7400MBq (100-200mCi) intravenously, and the drip should be completed within 60-90 minutes. The patient's heart rate and blood pressure should be closely monitored after the injection, and ECG monitoring should be performed.

treatment effect.

131I-MIBG has a certain effect on malignant pheochromocytoma, especially it can improve symptoms, control blood pressure, reduce the amount of catecholamines, etc., for small tumors, the tumor disappears and cures when the absorbed dose per gram of tumor tissue reaches more than 1000cGy; For patients with bone metastases, the effect of alleviating bone pain is obvious 3 to 5 days after administration, and the survival rate at 100 months is 6%.

Influencing factors

Reserpine can reduce the uptake of 131I-MIBG by tumors by 80% to 95%. Therefore, it should be discontinued before treatment. Cocaine also has a similar situation, and propranolol and other antihypertensive drugs have no effect.