Hyperthermia systems (BSD-2000, EHY-2000, superficial and interstitial applicators)

Deep regional hyperthermia systems surround the pelvis or abdomen with a ring of radiofrequency antennas whose phases and amplitudes are steered so that the energy adds up at the tumour; Pyrexar's BSD-2000 family, descended from BSD Medical's machines of the 1980s, is the reference system, with a version that runs inside an MRI scanner so that temperature can be mapped non-invasively. Superficial systems (BSD-500 and others) use microwave applicators for chest-wall recurrences and melanoma skin metastases; interstitial and intracavitary antennas heat cervical and prostate tumours from within; and Oncotherm's EHY-2000 and EHY-2030 deliver a lower-power modulated radiofrequency current between electrodes, marketed as electro-hyperthermia. Temperature is usually monitored with thermometry probes in catheters. Randomised trials showed benefit when hyperthermia was added to radiotherapy for locally advanced cervical cancer (Dutch Deep Hyperthermia Trial) and to chemotherapy for high-risk soft-tissue sarcoma (EORTC 62961), and it is used for recurrent breast cancer on the chest wall, bladder cancer and paediatric germ cell tumours in specialist centres, mainly in Germany, the Netherlands, Italy and Japan.

Hyperthermia is cheap per session, non-ionising and repeatable, but each treatment takes an hour or more of staff time, heating deep tumours evenly is physically hard and depends on the patient's anatomy and blood flow, temperature verification is invasive unless MRI thermometry is available, the evidence base is small and old, and reimbursement is patchy, which is why the installed base has stayed small.