THERMORADIOTHERAPY WITH COMBINED INTERSTITIAL AND EXTERNAL HYPERTHERMIA IN ADVANCED TUMORS IN THE HEAD AND NECK WITH DEPTH GREATER-THAN-OR-EQUAL-TO 3 CM

Advanced tumours in the head and neck 3-6 cm depth are too deep to be completely heated by external 915 MHz microwaves. A preliminary study was performed using interstitial plus external hyperthermia combined w ith external beam radiation therapy to heat tumours to depths greater- than-or-equal-to 3 cm. Nine advanced metastatic lesions of squamous ce ll carcinoma located in the head and neck were treated between 1987 an d 1990 with the combined hyperthermia technique and radiation doses of 38-60 Gy (mean of 49 +/- 3 Gy). The mean tumour volume was 58 +/- 9 ( SE) cm3 (range 24-94 cm3) with a mean tumour depth of 3.9 +/- 0.3 cm ( range 3-5.5 cm). The deeper aspects of the tumour were heated by inter stitial 915 MHz microwave antennas and the superficial aspects heated by external 915 MHz applicators. A single plane of polyurethane closed -end catheters, 16 Ga, were inserted under local anaesthesia approxima tely 1.5-2 cm apart in parallel arrays at the base of a lesion behind the sternomastoid muscle, or an equivalent site in a dissected neck, e xtending forward and angled deeply no more than 15'. Hyperthermia was administered twice weekly immediately after radiation therapy in a mea n of 5-3 +/- 0.7 external heat sessions (range 3-7) and a mean of 3.5 +/- 0.6 interstitial heat sessions (range of 1-6). Interstitial hypert hermia was usually administered in alternating sessions with external hyperthermia, but in some patients all of the sessions of one modality were administered followed by all of the sessions of the other modali ty. In no case were both interstitial and external heatings performed on the same day. Surface thermometers were used to monitor skin temper ature during external hyperthermia sessions. Results showed that by 8 weeks after completion of treatment, six lesions exhibited a complete response (67%) and three a partial response (33%). One of the partial responses continued to regress and became a complete response (78% com plete response). The recurrence rate in complete responders was 14% (1 /7) with time to recurrence of 7.7 months. Six lesions were recurrence -free at last follow-up of 21.3 +/- 8.8 months. Skin reactions were ab sent in four fields (44%), erythema was noted in five (56%) and therma l blistering in one (11%). Ulceration occurred only in association wit h tumour breakdown when the skin was infiltrated by tumour (three pati ents, 33%). The relative ease of the technique and the preliminary res ults suggest that a clinical trial is warranted to evaluate whether in terstitial plus external hyperthermia combined with external radiation therapy may be as effective in lesions 3-6 cm depth as external hyper thermia is in lesions less-than-or-equal-to 3 cm depth.