Electric Field Therapy (TTFields)

Note: This page is educational and reflects the state of the literature in 2025. It does not replace medical advice.

TL;DR

Tumor Treating Fields (TTFields) therapy delivers low-intensity, intermediate-frequency (100–300 kHz) alternating electric fields to the tumor through transducer arrays placed on the skin. The fields disrupt cancer cell mitosis, inhibit DNA replication and damage response, interfere with cell motility, and stimulate antitumor immunity. FDA-approved (Optune Gio) for newly diagnosed and recurrent glioblastoma; CE-marked for grade-4 glioma. Pivotal trials in non-small-cell lung cancer (LUNAR) and other indications expand the modality. Tolerable safety profile; biggest practical issue is device usage compliance.
Sources: [1]

1. How TTFields work

TTFields exploit the physics of dividing cells:
Sources: [1]

During mitosis, charged proteins (especially tubulin) align along the spindle.
An external alternating electric field at the right frequency creates dielectrophoretic forces that disrupt this alignment, leading to abnormal mitosis or cell death.
Effects extend beyond mitosis: TTFields slow DNA-damage repair, interfere with cell migration, and promote release of tumor antigens that can activate adaptive antitumor immunity.

The fields are delivered by transducer arrays (gel-coupled patches) on the skin around the tumor. Treatment is continuous — the patient wears the device most of the day; effectiveness correlates with usage hours per day (typically aiming for ≥18 h).
Sources: [1]

2. Clinical evidence

Glioblastoma (approved)

The pivotal EF-14 trial showed adding TTFields to maintenance temozolomide in newly diagnosed GBM improved median progression-free survival and overall survival vs. temozolomide alone. Result was the basis for FDA approval (Optune; rebranded Optune Gio).
Sources: [1]

Newly diagnosed GBM: TTFields + temozolomide → standard of care option.
Recurrent GBM: TTFields monotherapy approved.
Pediatric / AYA glioma: emerging data; investigational in younger patients.

Non-small-cell lung cancer (LUNAR)

The LUNAR Phase III trial (2024 reporting) showed benefit of TTFields added to standard therapy after platinum failure in metastatic NSCLC, leading to FDA approval expansion in 2024.
Sources: [1]

Other indications under study

Pancreatic cancer (PANOVA-3 Phase III).
Ovarian cancer (ENGOT-ov50/INNOVATE-3).
Mesothelioma (STELLAR data informed CE marking).
Brain metastases, gastric cancer, hepatic cancer — Phase I/II.
Pediatric oncology applications under exploration.
Sources: [1]

Combinations

TTFields + radiotherapy + temozolomide in GBM.
TTFields + immunotherapy — preclinical evidence of antigen release and adaptive immunity activation; combination trials emerging.
Sources: [1]

3. Practical aspects

Usage compliance is the main predictor of benefit — analyses consistently show dose-response by hours/day worn. Patient adherence support is essential.
Skin care — electrode sites need rotation, skin barrier products, sometimes topical steroids; the most common adverse event is dermatitis.
Lifestyle integration — patients can be ambulatory; battery packs are portable.
Cost and access — high; reimbursement varies dramatically across health systems.
No interaction with metallic implants other than at field-relevant sites; pacemakers and active implants are typically contraindications.

4. Safety profile

The dominant adverse events reported in trials:
Sources: [1]

Skin reactions at electrode sites — usually managed with topical care and rotation.
Mild headache, fatigue, mechanical irritation.
No significant systemic toxicity observed in pivotal trials.
No cumulative tissue damage at the recommended exposures.

The non-toxic profile is part of what makes TTFields combinable with chemotherapy and IO.

5. What's actually controversial

Magnitude of benefit in GBM has been debated — the OS gain in EF-14 was statistically significant but modest (~5 months median); clinical communities differ on cost-effectiveness.
Mechanism completeness — the original "mitotic disruption" framing has expanded into a multi-mechanism story (DNA damage, immunity, motility); some critics argue the mechanism is still imperfectly characterized.
Trial design — open-label control in EF-14 generates discussion about effect-size confidence.
Real-world adherence — real-world data show many patients don't reach the optimal usage hours that trials suggest.

These are honest critiques, not reasons to dismiss the modality. TTFields is a rare example of a non-pharmacological device-based therapy that crossed the rigorous oncology approval bar.

6. What technologists can build

Adherence monitoring — wearable sensors, patient-reported wearing time, EHR integration.
Treatment planning — finite-element electric-field simulation to optimize array placement (NovoTAL, academic FE software).
Outcome registries — link wearing-time profile to outcomes for individualized recommendations.
Skin-reaction prediction from imaging or photographs; preventive recommendations.
Combination predictors — model which patients gain from TTFields + IO based on baseline immune profile.

7. Brazilian context

Optune Gio is registered at ANVISA for glioblastoma; access is mostly via private insurance and select centers.
Multidisciplinary glioma services in HC-FMUSP, A.C. Camargo, Hospital Sírio-Libanês, ICESP, Hospital Albert Einstein and Beneficência Portuguesa cover TTFields-eligible patients.
Cost is a major barrier — academic-clinical partnerships and patient-support programs help selected patients access the device.
Brazilian academic groups participate in international trials (LUNAR-2, PANOVA-3) at large centers.

References

Khagi S, Kotecha R, Gatson NTN, et al. Recent advances in Tumor Treating Fields (TTFields) therapy for glioblastoma. Oncologist 2025;30:oyae227. PMID 39401002. https://doi.org/10.1093/oncolo/oyae227
U.S. National Cancer Institute. https://www.cancer.gov/about-cancer/understanding/what-is-cancer
American Cancer Society. https://www.cancer.org/cancer.html
Cleveland Clinic. Cancer (overview). https://my.clevelandclinic.org/health/diseases/12194-cancer
A.C. Camargo Cancer Center. https://accamargo.org.br
Fundação do Câncer (Brasil). https://www.cancer.org.br/
Ministério da Saúde / BVS. ABC do câncer. https://bvsms.saude.gov.br/bvs/publicacoes/abc_do_cancer.pdf
ANVISA. https://www.gov.br/anvisa/pt-br

PubMed citations retrieved via NCBI E-utilities.

Electric Field Therapy (TTFields) ​

TL;DR ​

1. How TTFields work ​

2. Clinical evidence ​

Glioblastoma (approved) ​

Non-small-cell lung cancer (LUNAR) ​

Other indications under study ​

Combinations ​

3. Practical aspects ​

4. Safety profile ​

5. What's actually controversial ​

6. What technologists can build ​

7. Brazilian context ​

See also ​

References ​