Tumor Treating Fields, or TTFields, are a cancer treatment that uses low-intensity, alternating electric fields to physically inhibit tumor cell growth. Unlike treatments using chemical drugs or ionizing radiation, TTFields is a non-invasive therapy that targets cancer cells based on their physical properties. The electric fields are delivered through a device worn by the patient to interfere with the rapid cell division that characterizes cancer.
How Tumor Treating Fields Work
The principle of Tumor Treating Fields therapy is to disrupt the process of cell division, known as mitosis. It generates specific, intermediate-frequency electric fields, between 100 and 300 kHz. These fields are tuned to interfere with the highly organized structures that cancer cells form when they divide. This selective targeting is possible because many healthy cells in the body divide much more slowly and are less susceptible.
During mitosis, a structure called the mitotic spindle is formed by tiny, charged proteins. This spindle is responsible for accurately separating the duplicated chromosomes into two new daughter cells. The external electric fields from the TTFields device exert a force on these charged proteins, disrupting their alignment. This interference prevents the mitotic spindle from functioning correctly, halting cell division and leading to the death of the cancer cell.
This mechanism is primarily physical rather than chemical or biological. The alternating nature of the fields causes constant reorientation of polar molecules within the dividing cell, creating an environment where the machinery of mitosis cannot assemble properly. Consequently, the cancer cell is unable to complete its replication cycle.
The Patient Experience with Treatment
Living with Tumor Treating Fields therapy involves integrating a portable medical device into daily life. The system consists of two main components: insulated ceramic discs, called transducer arrays, that are applied directly to the skin, and a small, portable field generator that powers them. Patients or their caregivers are trained to manage the device at home, which includes regularly changing the transducer arrays.
For treatment to be optimal, the device must be worn for at least 18 hours a day, meaning patients continue to receive therapy while sleeping, working, and engaging in most of their normal activities. The field generator is carried in a specially designed backpack or shoulder bag, allowing for mobility.
For glioblastoma, a type of brain cancer, the transducer arrays are placed on the patient’s scalp. This requires the patient to keep their head shaved throughout the treatment period to ensure good contact. The arrays are changed and repositioned every few days to maintain proper function and to minimize skin irritation from the adhesive.
Cancers Treated and Clinical Efficacy
The Food and Drug Administration (FDA) has approved TTFields therapy for specific types of cancer based on clinical trials. It is used for patients with newly diagnosed and recurrent glioblastoma (GBM), malignant pleural mesothelioma that cannot be removed with surgery, and certain types of non-small cell lung cancer. In these settings, TTFields therapy is not used as a standalone treatment but is integrated with other standard cancer therapies.
For newly diagnosed glioblastoma, TTFields are used in combination with the chemotherapy drug temozolomide, following surgery and radiation. Clinical studies have shown that adding TTFields to the standard chemotherapy regimen improves patient outcomes. A clinical trial demonstrated an increase in both progression-free survival and median overall survival for patients who received the combination therapy.
The efficacy of TTFields is linked to its ability to make cancer cells more vulnerable to other treatments. Evidence suggests the electric fields can increase the permeability of a cancer cell’s membrane, allowing chemotherapy drugs to enter and work more effectively. This synergistic effect is a reason the therapy is often combined with other treatments.
Side Effects and Management
The side effects from TTFields are localized and differ from systemic treatments like chemotherapy. The most common issue reported by patients is skin irritation at the site where the transducer arrays are placed. This can range from mild redness and itching to a more pronounced rash, caused by the adhesive on the arrays and the continuous presence of the electric field.
Physicians manage this side effect through proactive skin care. This often involves the use of moisturizers, topical corticosteroids to reduce inflammation, and careful rotation of the array placements each time they are changed. Patients are taught how to inspect their skin daily and communicate with their care team about any irritation.
Because the electric fields are directed locally at the tumor site, TTFields therapy does not cause the systemic side effects that are common with many chemotherapy drugs. Patients do not experience nausea or suppression of the immune system. This localized side effect profile can contribute to a better quality of life for patients during treatment.
Ongoing Research and Future Applications
The application of TTFields is an active area of cancer research, with clinical trials underway to explore its potential for other types of cancer. Scientists are investigating the effectiveness of this therapy against a variety of solid tumors, including pancreatic cancer, ovarian cancer, and gastric cancer. These studies aim to determine if the anti-mitotic effects can be replicated in other rapidly dividing cancer cells.
This research extends to exploring new combinations of TTFields with other cancer treatments. Studies are evaluating its use alongside different chemotherapy agents, radiation therapy, and newer immunotherapy drugs. The goal is to identify synergistic partnerships that could lead to more effective treatment regimens.
The technology itself is also evolving. Researchers are working to optimize the delivery of the electric fields and enhance the design of the device for greater patient comfort and ease of use. As understanding of the mechanisms deepens, it may become possible to refine the therapy for specific tumor types.