Current and potential role of thermoradiotherapy for solid tumours

The disappointing results for inoperable, locally advanced or recurrent solid tumours of the uterine cervix, rectum, chest wall, liver and deep seated, high-risk sarcomas after conventional radiotherapy alone necessitate the search for improved treatments. A benefit from simultaneous radiochemotherapy with regard to local tumour control and survival has been shown for a rising number of tumour entities. Radiofrequency hyperthermia is established in only a few centres, and represents another option to intensify the effect of radio- and chemotherapy. Altogether 11 randomised phase III trials with more than 1,000 patients proved the combination of hyperthermia (40-42 degrees C for at least 1 h) and radiation therapy in reference to local tumour control. Two of these trials could demonstrate a survival benefit; e.g. in locally advanced cervical cancer, stage FIGO IIB-IVa, the 3-year survival was improved from 27 to 51% with the addition of hyperthermia. Frequently trial design (main endpoint local tumour control), a low number of patients or a short follow- up period are the reasons why most trials of thermoradiotherapy failed to demonstrate a survival benefit. Disadvantageous effects of hyperthermia like an increased rate of distant metastases as a result of hyperthermia-induced elevated perfusion can be largely ruled out. While at the moment the equivalence of thermoradiotherapy and radiochemotherapy is still under evaluation, future studies have to investigate the question whether hyperthermia can add benefits when used in combination with simultaneous radiochemotherapy. An ongoing investigation of hyperthermia in multimodal treatment strategies for locally advanced solid tumours is warranted. These trials will help to improve temperature monitoring and temperature distribution and define particular groups of patients who will profit from the addition of hyperthermia. The 'Interdisziplinäre Arbeitsgruppe Hyperthermie', a working group of the German Cancer Society, introduces clinical protocols, treatment devices, and provides information for patients at www.hyperthermie.org.