聲波反擊：超音波的免手術癌症治療革命

Ultrasound technology, which has long been used to help doctors see inside the body, is now being developed as a new way to treat cancer without surgery. This exciting change is thanks to scientists like Zhen Xu, who began her research at the University of Michigan. Xu wanted to find a way for doctors to remove diseased tissue without having to perform invasive surgery. She experimented with high-frequency sound waves, known as ultrasound, on pig hearts. Her experiments were so loud that her lab mates complained, so she changed the number of ultrasound pulses she used. Surprisingly, this adjustment made her treatment more effective. She watched as a hole formed in the pig heart tissue within a minute, proving that ultrasound could break up living tissue.

This discovery led to the development of a treatment called histotripsy. Histotripsy uses focused ultrasound waves to target and destroy cancerous tumors. The device sends ultrasound waves to a very small area, about the size of the tip of a coloring pen. A robotic arm helps guide the ultrasound to the exact spot on the tumor. The ultrasound is delivered in quick bursts, creating tiny bubbles that expand and collapse in microseconds. These bubbles break apart the tumor tissue, and the patient’s immune system cleans up the remains. The treatment is fast, non-toxic, and non-invasive, meaning patients usually do not need to stay in the hospital overnight. In October 2023, the US Food and Drug Administration approved histotripsy for treating liver cancer. Studies funded by HistoSonics, the company that commercialized Xu’s technology, found that the treatment was successful and generally safe, with only rare complications like pain or bleeding.

Ultrasound is also used in other cancer treatments, such as High-Intensity Focused Ultrasound (HIFU). HIFU works by focusing ultrasound waves to heat and destroy cancer tissue, similar to how a magnifying glass can burn a leaf. HIFU is commonly used for prostate cancer and is about as effective as surgery. Both histotripsy and HIFU are performed while the patient is under anesthesia to prevent movement. Unlike HIFU, histotripsy does not use heat, so it is less likely to damage healthy tissue nearby. However, not all cancers can be treated with these methods. Bones and air-filled organs can block ultrasound waves, making it difficult to reach some tumors. Researchers are also exploring ways to combine ultrasound with other treatments, like chemotherapy and radiation, to make them more effective. For example, ultrasound can help open the blood-brain barrier, allowing medicine to reach brain tumors. It can also help the immune system recognize and attack cancer cells.

There are still challenges to overcome. Some scientists worry that breaking up tumors with ultrasound could spread cancer cells, but studies have not shown this to be a problem so far. More research is needed to understand how these treatments work and how they can be improved. Ultrasound is not a cure-all, but it offers hope for less painful and less invasive cancer treatments. Zhen Xu and other researchers believe that their discoveries will help patients avoid unnecessary suffering and improve their chances of recovery in the future.