Histotripsy

Histotripsy is a way to destroy a tumor using sound. A treatment head filled with water rests on your skin, over the liver. It sends very short, very powerful pulses of ultrasound that all meet at one small point inside the tumor. At that point, the pulses create clouds of tiny bubbles that form and collapse in millionths of a second. That rapid motion breaks the tumor cells apart, turning the tumor into a liquid that the body clears away over the following weeks to months.

Unlike microwave ablation or cryoablation, histotripsy does not use heat or cold, and nothing goes through the skin. The machine moves the focal point in a pattern until the whole tumor, plus a thin safety margin, has been treated.

The FDA cleared the first histotripsy system for treating liver tumors in October 2023. That makes it one of the newest treatments in cancer care. Early results are encouraging, but long-term results, such as how often tumors come back after several years, are still being studied.

During treatment, the tumor is watched on live ultrasound. The treated area appears as a bright, shimmering cloud of bubbles, and afterward it shows up on MRI or CT as a darker, rounded zone where the tumor used to be.

Histotripsy is cleared for tumors in the liver, both cancers that start in the liver, called hepatocellular carcinoma (HCC), and cancers that have spread to the liver from elsewhere, such as the colon. It may be an option when surgery is not a good choice or when you would prefer to avoid needles, and sometimes it is used alongside other treatments. It is being studied for the kidney, pancreas and other organs, but those uses are still in clinical trials.

The biggest limit is access. Ultrasound has to reach the tumor through a clear window. Ribs, lung and gas in the bowel block sound, so some tumors cannot be reached even if they are small.

Other options include Y-90 radioembolization, chemoembolization, focused radiation (SBRT) and medicines. Because histotripsy is new, we compare it honestly with treatments that have longer track records before recommending it.

1. 1
   Anesthesia

   You are put fully to sleep so you stay still. The anesthesia team can also control your breathing, which keeps the liver steady.

2. 2
   Setting up

   The treatment head, with a water bath or bag on its face, is placed on your skin over the liver. We use its built-in ultrasound to find the tumor and plan the treatment zone.

3. 3
   Treatment

   The machine sends rapid pulses of focused ultrasound and moves the focal point through the whole tumor. We watch the treated area on live ultrasound the entire time.

4. 4
   Waking up

   You wake in recovery with no incision and no stitches. Many people go home the same day or the next morning.

Most people have mild soreness over the treated area and feel tired for a few days. Some have a low fever or nausea. Many return to light activity within a few days.

1. First 24 hours
   Rest. No driving for 24 hours after anesthesia. Mild soreness is common.
2. Days 2–7
   Most people resume light daily activities. Tiredness is the most common complaint.
3. About 1–2 months
   An MRI or CT checks that the whole tumor was treated. The treated area slowly shrinks as the body absorbs it.
4. Every few months
   Regular scans watch for any tumor that comes back, as after any liver tumor treatment.

In the main study that led to FDA clearance, the planned treatment zone was fully treated in about 95 in 100 tumors, and serious complications were uncommon. These were short-term results in a limited number of patients. How well histotripsy controls tumors over years, and how it compares head to head with other treatments, is still being measured.

I am excited about histotripsy, and I am also careful with it. The first thing I do is look at the tumor on ultrasound myself, because if sound cannot get a clear path, the machine cannot treat it. Then I lay out, side by side, what we know about histotripsy and what we know about options with longer track records, so you can choose with clear eyes.

Fabio Komlos, MD, interventional radiologist · About Dr. Fabio Komlos