High-Intensity Focused Ultrasound to Treat Cancer
High-intensity focused ultrasound (HIFU) is a non-invasive therapy that uses focused ultrasound waves to ablate or heat cells or tissues. The intense heat causes coagulation of tissues and heat shock to cells, ultimately destroying them (High-intensity focused ultrasound (HIFU) – CIRSE, 2018). HIFU is a newly developed treatment for cancer. Cancer cells are killed due to the high heat produced by the high-frequency waves from ultrasound. That it can kill the cancer cells without any invasive surgeries directly. This treatment is more suitable for benign cancers (contained in one area) and single or large parts of tumours; ultimately, this treatment is only appropriate for some cancers (High intensity focused ultrasound | Other treatments | Cancer Research UK, 2018). In addition, HIFU can be used for cosmetic purposes in the face.
Image is courtesy of cirse.org.
An example of suitable cancer for HIFU is prostate cancer. Prostate cancer is the third-leading cause of death in men as 20% of cancer in men is located in the prostate, and 10% of cancer deaths in men are caused by prostate cancer (Prostate cancer statistics - Canadian Cancer Society, 2020). It is caused by the loss of control of growth and division in prostate cells, and ultimately, the prostate cells do not function properly, and a malignant tumour in the prostate forms (What is prostate cancer? - Canadian Cancer Society, 2021). To treat prostate cancer, a radical prostatectomy, the removal of the prostate, or transurethral resection of the prostate (TURP), the removal of the prostate through the urethra is performed. Both are invasive surgeries as tissues around the prostate may also be removed. Radiation, hormonal, and chemotherapy are also methods to treat prostate cancer. Still, these therapies have side effects such as radiation therapy can damage tissues around the focused area, hormonal therapy can interfere with the body’s homeostasis, and chemotherapy’s side effects can be intense for patients (Treatments for prostate cancer - Canadian Cancer Society, 2021)(Chemotherapy and other drug therapies - Canadian Cancer Society, 2021). In contrast, HIFU is minimally invasive, which results in minimal hospital stay, recovery time, and side effects. HIFU also does not harm the healthy tissue around the cancer cells. HIFU for prostate cancer is still relatively an experimental procedure. Under strict criteria, patients with prostate cancer can receive this treatment (High-Intensity Focused Ultrasound (HIFU) for Prostate Cancer, 2020).
Moreover, liver tumours may also be targeted using HIFU and bring multiple advantages. Collateral cancers can metastasis in the liver and are usually treated through the resection of the affected tissue combined with chemotherapy—invasive surgeries. Hepatic resection of the solid tumour is only feasible in 10-25% of cases with the added risk of an operative mortality rate up to 5%. Chemotherapy to treat the liver tumour provides an objective response rate of 20-50% with a 12-month survival rate. According to the clinical trial that explored the use of HIFU for liver tumours, transient pain was described in 83% of patients and superficial skin burns in some subjects. However, there was radiological and histological evidence of 28 of the 30 patients who received the HIFU treatment having ablation of the target. There were minimal physiological consequences to hepatic and renal functions (Leslie et al., 2012).
Image is courtesy of ncbi.nlm.nih.gov.
There are currently multiple clinical trials exploring the feasibility of HIFU of liver-related cancer. This use of HIFU has been approved in China, Russia, Europe, and Korea for liver cancer (Liver Tumors, 2021).
Using HIFU for cosmetic purposes is still a relatively new procedure. The ultrasound energy is used to encourage collagen production, which gives the face a plump and firm appearance. Small clinical trials have found HIFU to be effective in facial lifting and refining wrinkles. This procedure works by thermally causing cellular damage to layers of skin below the surface. This damage stimulates cells to produce collagen—a protein that provides structure to tissues—for repairing. Since the ultrasound energy is directed to areas below the skin, there is no damage to the outward appearance of skin or adjacent tissues. The procedure is noninvasive, and a painless alternative to the conventional facelift surgery that is invasive and requires going under anesthesia. Moreover, HIFU is less costly, but repeated procedures may be needed as results may not last as long. Facial rejuvenation using HIFU has been through clinical trials in South Korea and US (both of which had successful results), but has not been approved by the FDA; only the use of HIFU for brow lifts and to improve lines and wrinkles in the upper chest and neckline has been approved (Healthline & Cafasso, 2019).
In conclusion, the innovative uses of high-intensity focused ultrasound therapeutically and cosmetically carry heavy benefits in terms of patient side effects and outcomes. The main advantage of HIFU’s noninvasiveness allows for a far quicker recovery time compared to conventional surgical procedures. Many of HIFU’s functions are still being explored through clinical trials to ensure safe and effective clinical usage of this technology, and the results look promising.
Article author: Ashley Chen
Article editors: Sherilyn Wen, Maria Giroux