THERMORADIOTHERAPY FOR SUPERFICIAL TUMOR DEPOSITS IN THE HEAD AND NECK

Tumour deposits in the head and neck region were treated with hyperthe rmia using 915 MHz external microwave applicators and radiation therap y between 1986 and 1990. The mean (+/-SE) radiation dose was 47 +/- 2 Gy (range 21-77 Gy). All but four patients had failed previous therapy . Mean tumour volume was 40 +/- 10 cm(3) (range 0.3-276 cm(3)). Hypert hermia was administered biweekly in 80% of the patients in 6.0 +/- 0.4 sessions (range 1-10); thermometry involved 3.6 +/- 0.4 catheters (ra nge 1-9) and 5.7 +/- 0.4 sensors (range 1-12) per tumour. Of the 50 le sions evaluable for response, 29 had a complete response (58%), and 20 had a partial response (40%). Lesions were stratified by depth. In tu mours considered potentially heatable (i.e. depth less than or equal t o 3 cm and lateral dimensions at least 2 cm less than boundary of appl icator), the complete response rate was 81% (26/32, 47 +/- 2 Gy, 15 +/ - 3 cm(3)); whereas for patients with tumours deeper than 3 cm, the co mplete response rate was 17% (3/18, 48 +/- 3 Gy, 110 +/- 21 cm(3)), p= 0.0001. Among lesions 3 cm depth that exhibited a complete response, s ix recurred (24%, 5.8 +/- 1.8 months) while 20 lesions were recurrence free response, six recurred (24%, 5.8 +/- 1.8 months) while 20 lesion s were recurrence free at last follow-up of 11.9 +/- 1.2 months. The o verall survival of patients with lesions less than or equal to 3 cm de pth was 11.5 +/- 1.3 months (range 2.4-32.3 months) while for patients with lesions >3 cm depth survival was 6.7 +/- 0.9 months (range 2.1-1 8.6 months), p=0.01. In superficial lesions with depth 13 cm, multivar iate logistic regression analysis indicated that the model best correl ating with complete response included radiation dose (p=0.08) and tumo ur volume (p=0.08, model p=0.004). Multivariate proportional hazard an alysis indicated that the model best correlating with duration of loca l control included tumour depth (p=0.03) and previous radiation therap y (p=0.08, model p=0.006). Twenty-two fields were treated without any skin reactions (39%), 23 evidenced erythema (40%) and eight thermal bl istering (14%). Ulceration occurred in 11 treatment fields but in all but one of these cases the ulceration may have been due to tumour brea kdown as there was direct invasion of the skin by tumour prior to the initiation of treatment. The maximal skin temperature was the best pre dictor of morbidity although the correlation was not statistically sig nificant (p=0.19).