TUMOUR TREATING
FIELDS (TTFIELDS)
TTFields deliver low-intensity alternating electric fields through transducer arrays worn on the shaved scalp — disrupting mitotic spindle formation to prevent cancer cell division without affecting non-dividing normal brain cells. The EF-14 trial showed the largest single-treatment OS improvement in newly diagnosed GBM since 2005.
analyticsAt a Glance
- check_circleEF-14 Phase III trial: TTFields + TMZ improved median OS from 16.0 to 20.9 months vs TMZ alone — 5-year OS 13% vs 5%
- check_circleFDA-approved for newly diagnosed GBM (2015) and recurrent GBM (2011) — Optune device by Novocure
- check_circleCompliance-dependent: patients wearing device >22 hours/day achieved median OS of 24.9 months in EF-14
- check_circleNot yet routinely available in China and India — CancerFax advises on access pathways and device programmes
How TTFields Work: Disrupting Cell Division with Electric Fields
TTFields apply low-intensity (1–3 V/cm), intermediate-frequency (200 kHz) alternating electric fields through four arrays of insulated electrodes worn on the scalp. At this frequency, the oscillating field exerts dielectrophoretic forces on polar molecules with high dielectric constants — specifically the tubulin dimers that polymerise to form the mitotic spindle during cell division. This disrupts spindle assembly, impairs chromosome segregation, and causes abnormal mitosis — leading to mitotic catastrophe and cell death.
“TTFields are not chemotherapy, not radiation, and not immunotherapy — they are a fourth treatment modality. They work through a completely different mechanism from anything else in GBM, which is why they are additive to TMZ rather than competing with it.”
Why GBM Cells Are Specifically Vulnerable
TTFields at 200 kHz are specifically effective against GBM and other tumours because: (1) dividing tumour cells are far more susceptible than non-dividing normal neurons, which are post-mitotic and largely unaffected; (2) GBM's high mitotic rate means more cells are in division at any given time; (3) the blood-brain barrier concentrates the electric field effect within the CNS. Normal brain cells — protected by their non-dividing state — experience minimal biological disruption.
The Optune Device: What Patients Wear
The Optune system consists of four transducer arrays — arrays of ceramic disc electrodes embedded in a hypoallergenic medical patch applied to the shaved scalp. Arrays are connected to a portable electric field generator (approximately 1.2 kg) carried in a shoulder bag or backpack. The device must be worn continuously — the recommended minimum is 18 hours per day; outcomes are best at >22 hours per day. Arrays require replacement every 3–4 days.
The EF-14 Trial: TTFields + TMZ vs TMZ Alone
The EF-14 Phase III trial is the definitive evidence base for TTFields in newly diagnosed GBM — its 5-year follow-up data establish TTFields as the most significant advance in GBM treatment since the Stupp protocol.
EF-14: Overall Survival and Progression-Free Survival
Source: Stupp R et al., JAMA 2017;318(23):2306–2316; 5-year update Lancet Oncol 2021. 695 patients. Newly diagnosed GBM after standard CRT.
- Median OS: TTFields + TMZ20.9 mo
- Median OS: TMZ alone16.0 mo
- 5-year OS: TTFields + TMZ13%
- 5-year OS: TMZ alone5%
- Median PFS: TTFields + TMZ7.1 mo
- Median PFS: TMZ alone4.0 mo
EF-14: OS by TTFields Compliance Level
Patients wearing device more hours per day had significantly better outcomes — establishing compliance as the dominant TTFields outcome predictor
- Median OS: TTFields compliance >22 hrs/day24.9 mo
- Median OS: TTFields compliance 18–22 hrs/day21.1 mo
- Median OS: TTFields compliance <18 hrs/day13.4 mo
- Median OS: TMZ alone (control arm)16.0 mo
TTFields Eligibility, Practical Requirements, and Device Management
TTFields eligibility and day-to-day device management are closely linked — understanding both is essential before committing to this treatment.
| Aspect | Details | Practical Note |
|---|---|---|
| FDA/CE approved indications | Newly diagnosed GBM (after concurrent CRT, with adjuvant TMZ); recurrent GBM (monotherapy) — EF-11 trial data | Used throughout the 6-cycle adjuvant TMZ phase for newly diagnosed GBM; can continue beyond TMZ course |
| Contraindications | Active implantable devices (pacemaker, ICD, deep brain stimulator, cochlear implant); skull defects in treatment field; known skin hypersensitivity to gel/adhesive | Skull defects from surgery should be documented — arrays must not be placed over metallic bone flap; discuss with Novocure representative |
| Hair requirements | Complete scalp shave required — maintained throughout device use; regrowth requires reshaving every 3–4 days for array replacement | Most patients and families find scalp shaving manageable; wigs and head coverings are compatible with device use |
| Array placement | Four transducer arrays applied in two perpendicular field directions; placement layout determined by Novocure's proprietary NovoTAL algorithm based on tumour location MRI | NovoTAL planning performed by Novocure engineers; prescription submitted by treating neuro-oncologist |
| Array replacement | Arrays replaced every 3–4 days — patients and carers trained for home self-replacement | Replacement materials (arrays, conductive gel, adhesive) shipped directly to patient; telephone support available |
| Compliance monitoring | Device records daily usage hours; report submitted monthly to prescribing physician and Novocure | Compliance data are shared with the treating team — discussed at monthly clinical review |
| Scalp reactions | Local skin irritation (erythema, dermatitis) in 50–60% of patients — managed with topical corticosteroids, array repositioning, and skin care | Grade 3+ scalp reactions requiring device pause occur in ~2%; most mild reactions resolve with topical treatment without discontinuation |
| Physical activity | Shower possible (device disconnected); swimming not possible; physical activity generally unrestricted while wearing device | Device is worn during sleep — positioning in bed is adapted; patients generally report adaptation within 1–2 weeks |
| Cost | USD 20,000–25,000 per month in the US; lower in Europe; not routinely reimbursed in China or India | Novocure offers patient assistance programmes; CancerFax advises on access pathways and potential cost-support options |
TTFields: Benefits vs Limitations
TTFields represent a genuine advance in GBM treatment — but their practical demands and access barriers require honest assessment.
Benefits
- 4.9-month median OS improvement over TMZ aloneThe largest single-treatment survival improvement in newly diagnosed GBM since the Stupp protocol — EF-14 is Level 1 evidence.
- No systemic toxicity — different mechanism from TMZTTFields are not chemotherapy — no neutropaenia, nausea, or fatigue attributable to the device itself. Combined with TMZ without additive haematological toxicity.
- Benefit across MGMT subgroupsEF-14 showed OS benefit in both MGMT-methylated and unmethylated subgroups — particularly valuable for MGMT-unmethylated patients who have limited options.
- Compliance-dependent dose-responsePatients who achieve >22 hours/day wear time achieve the best outcomes — motivation, device management training, and support network improve compliance.
Limitations
- Continuous wear required — lifestyle impactWearing an electrical device on the scalp ≥18 hours/day for months is a significant lifestyle commitment — accepted by many patients but not all.
- Scalp shaving and visible deviceComplete scalp shave is required for array placement. The visible transducer arrays and connecting cables have a psychosocial impact that varies substantially between patients.
- Limited availability outside US, EU, and JapanThe Optune device is not routinely approved or available in China, India, and many other countries. Access requires special import, compassionate use, or patient assistance programmes.
- High cost — reimbursement challenges globallyUSD 20,000+ per month in the US — not covered by most Asian or African insurance systems. Cost access remains the primary barrier for most international patients.
TTFields: Key Clinical Numbers
The most important figures from the EF-14 trial and clinical practice.
- 20.9 moMedian OS: TTFields + TMZ in EF-14 (vs 16.0 months TMZ alone)The primary efficacy outcome — a 30.6% improvement in median overall survival compared to TMZ alone in the adjuvant setting.
- 13%5-year OS with TTFields + TMZ vs 5% with TMZ alone (EF-14)The long-term survival benefit — a 2.6× improvement in 5-year survival rate — changes the prognosis conversation for newly diagnosed GBM.
- 24.9 moMedian OS with compliance >22 hours/day (EF-14 subgroup)The highest median OS reported in any GBM trial — demonstrating that compliance is not an abstract metric but a clinically decisive variable.
- 200 kHzTTFields frequency specifically selected for GBMThe frequency at which electric fields most effectively disrupt GBM mitotic spindles — different tumour types require different frequencies (e.g. 150 kHz for NSCLC in LUNAR trial).
More from the Glioblastoma Resource Library
Continue exploring GBM treatment — from the Stupp protocol to emerging and recurrence strategies.
- ↑ Glioblastoma — Complete Guide
- What Is Glioblastoma (GBM)? Understanding the Most Aggressive Brain Tumour
- The Stupp Protocol: Surgery, Radiation, and Temozolomide for GBM
- MGMT Methylation Testing: Why It Is Essential Before GBM Treatment
- IDH Mutation in Brain Tumours: What It Means and Why It Matters
- GBM at Recurrence: Treatment Options After First Progression
Frequently Asked Questions
Common questions from GBM patients and families exploring TTFields/Optune.
About TTFields and Optune
Does TTFields (Optune) cure GBM?
No — TTFields, like all other GBM treatments, is not curative. It extends survival and improves the 5-year survival rate but does not eliminate GBM in the vast majority of patients. The EF-14 trial showed 13% of patients in the TTFields + TMZ arm were alive at 5 years, compared to 5% in the TMZ-alone arm. That 13% represents a meaningful subgroup of long-term survivors — but also means 87% of patients did not survive 5 years. The honest framing is that TTFields makes a clinically meaningful contribution to a disease that remains incurable with current standard treatments, and it remains the best non-surgical advancement in GBM since 2005.
How do I access the Optune device in China or India?
The Optune device is approved in the US, EU, Japan, Israel, and a small number of other markets. It is not routinely approved in China or India as of 2024. Access pathways for patients in these regions include: (1) Novocure compassionate use programme — Novocure reviews individual patient applications; (2) purchase of the device through specialty medical device import channels — available in some larger cities; (3) participation in a clinical trial using TTFields, including Chinese trials evaluating the technology; (4) receiving part of GBM treatment in a country where Optune is approved. CancerFax can advise on which of these pathways is most feasible for your specific location and disease situation — contact us with your country and a brief clinical summary for personalised advice.
Can I wear TTFields if I have a pacemaker?
No — an active implanted electronic device (pacemaker, implantable cardioverter-defibrillator, cochlear implant, vagal nerve stimulator, deep brain stimulator) is a contraindication to TTFields. The alternating electric field could theoretically interfere with these devices' function. This contraindication is listed in the Optune Instructions for Use and is absolute. If you have any implanted electronic device, you are not eligible for TTFields regardless of GBM diagnosis. Discuss alternative treatment strategies with your neuro-oncologist — the standard Stupp protocol without TTFields remains appropriate, and clinical trial access may offer alternatives.
What MGMT status benefits most from TTFields?
This is a commonly asked question given that MGMT-unmethylated patients have the least benefit from temozolomide. The EF-14 trial showed that TTFields added survival benefit in BOTH MGMT-methylated and MGMT-unmethylated subgroups — with a trend toward larger absolute benefit in the unmethylated group (who have less to gain from TMZ alone). This makes TTFields especially valuable for MGMT-unmethylated patients, where TMZ provides limited protection and the addition of TTFields is the most meaningful augmentation of standard treatment. For MGMT-methylated patients, the already-higher survival with TMZ is further improved by TTFields — achieving median OS approaching 25 months in high-compliance patients.
How CancerFax Helps
CancerFax is a specialist cancer access and patient-navigation platform. We help patients and families understand their options, organise medical records, coordinate hospital communication, and support cross-border treatment planning where appropriate.
We help collect and organise reports, scans, pathology, biomarker results, and treatment history for structured case review.
We communicate with hospitals or trial teams to assess whether a case may be suitable for further screening.
We support appointment coordination, document submission, translation, and direct communication with international departments.
For international patients, we help with practical coordination — travel planning, hospital admission guidance, and local support.
If this option is not suitable, we help explore other relevant treatments, clinical trials, or advanced care pathways.
From inquiry through to follow-up, our coordinators provide a single point of contact for the family.
CancerFax does not guarantee treatment access, eligibility, or clinical outcome. Our role is to help patients access accurate information, structured review, and appropriate specialist pathways.
Exploring TTFields Access for GBM?
CancerFax advises GBM patients on TTFields eligibility and access — including Novocure patient programmes, device availability in China and India, and specialist neuro-oncologists who integrate TTFields into GBM treatment planning.
This content is for informational purposes only and does not constitute medical advice. Always consult a qualified oncologist before making treatment decisions.