TTFields and the Limits of Extrapolation

Oncology needs precise distinctions between measuring a tumor and treating one. Neither a membrane-voltage observation nor a tissue impedance reading automatically identifies an effective field regimen for a patient.

A defined field regimen

The EF-14 randomized trial studied TTFields via scalp arrays at 200 kHz for at least 18 hours a day in 695 patients with newly diagnosed glioblastoma after radiochemotherapy. Maintenance temozolomide was given in both arms. Median overall survival from randomization was 20.9 months with TTFields plus temozolomide and 16.0 months with temozolomide alone. The result does not imply that patients can forgo systemic treatment.

How to evaluate the next question

Electro-hyperthermia, nanotechnology-based delivery and electrical profiling each require their own evidence. A hypothetical workflow that measures a tumor, selects a waveform and adjusts it based on response has several independent validation steps: reliable measurement, a reproducible selection rule and improved patient outcomes over an appropriate comparator. The EF-14 trial did not test such a workflow or metastatic disease.

Outpatient convenience and quality of life matter, but neither can be presumed for a new device. They belong among the prespecified outcomes of future studies, alongside adverse events and survival.

From tumor electrical features to a defined intervention Describe the tumor's electrical features

Choose one defined field or device modality

Test that modality in the specified cancer and setting

What the linked references do not establish: The cited glioblastoma TTFields trial does not establish effectiveness for all tumors or other electrical therapies.