Cancer

Short Introduction

Principle By injecting pure alcohol (i.e., ethanol) into the tumor bed, blood flow to the cancer is blocked. The alcohol induces tumor destruction by drawing water out of the tumor cells (dehydrating them) and denaturing the structure of the cellular proteins, resulting in complete ablation of the tumor. Technique The 100% (absolute) alcohol is injected through the skin (percutaneously) and into the tumor using a very thin needle with the help of ultrasound or CT guidance. It may take up to five or six sessions of injections to completely destroy the cancer. Indication Alcohol injection may be appropriate for patients with any of the following:

• a single HCC lesion smaller than 5 cm in diameter
• up to three lesions smaller than 3 cm in diameter that are localized but unresectable due to the location in the liver, concomitant medical considerations (cirrhosis), or even limited bilateral tumors
• a lesion surrounded by a shell consisting of scar tissue (fibrous encapsulation) and not near the surface of the liver

Tumor response

Tumor response rates to alcohol injection have been reported to be 90-100% in liver cancer smaller than 2 cm in diameter, 70% in liver cancer of 3 cm in diameter, and 50% in 5 cm in diameter

Percutaneous ethanol (alcohol) injection (PEI) therapy was first performed in 1983 inJapan. Ultrasound guidance is used to place up to absolute alcohol into the lesion. Now this modality has been widely used and is accepted as an attractive alternative to surgery in patients with small hepatocellular carcinoma (HCC).

PRINCIPLE

The toxic effects of ethanol are at the cellular level. Ethanol diffuses into the cell and causes nonselective protein denaturation and cellular dehydration, leading to coagulation necrosis. Subsequent fibrosis and small vessel thrombosis also contribute to cellular death.

PROCEDURE

Ethanol (Alcohol) ablation is generally performed under sonography guidance by using a 20-gauge needle. This needle has two side holes at its tip, which allows better dispersion of the alcohol into the tumor tissue. The needle tip is placed close to the peripheral margin of the tumor. Absolute alcohol (100%) is slowly injected under real-time ultrasound control. If the alcohol ran off quickly into the blood stream rather than staining the tumor tissue, as observed by real-time ultrasound, then this indicates that the needle tip is not in the substance of the tumor. The needle is then repositioned. The goal of this procedure is to achieve a black stain in the tumor tissue, as evidenced on imagings. A maximum of 10 ml of 100% alcohol is injected per site, with maximum of 20 ml per session. At the end the procedure, 1% Lidocaine is injected along the needle track as the needle is slowly being withdrawn. The injection appears to lessen the amount of discomfort the patient experiences following the session. The session is terminated prematurely, that is by using less than 10 ml of alcohol, if the patient experiences significant discomfort or if the tumor tissue appears to be completely ablates. The numbers of session per patient, generally, are once or twice per week for four to six sessions, depending upon the tumor size and the amount of residual tumor identifies on CT or ultrasonography.