External microwave hyperthermia combined with radiation therapy for extensive superficial chest wall recurrences

From January 1986 to January 1987 at Hahnemann University Hospital, Philadelphia, 13 patients were treated with combined external hyperthermia and radiation therapy to extensive chest wall recurrences from carcinoma of the breast. A total of 145 hyperthermia sessions for 27 different hyperthermia fields were analyzed in this study. Mixed photon (10 MV) or electron beam (6-15 MeV) radiation therapy (16-50.5 Gy, two to five weekly fractions of 1.5-2.0 Gy) was given followed within 30 min by external 915-MHz microwave hyperthermia (two weekly fractions for 60 min at 41-44 degrees C). Temperature recordings were made at up to 24 points in the center and periphery and at junctions of fields. The thermal dose concept of Sapareto (T43 Eq) was used to evaluate the relationship between maximum or minimum temperature (TMAX/TMIN) and rates of complication and of CR for each treatment field. Our results indicate that total or mean TMAX43 Eq per hyperthermia treatment field is related to complication rate, whereas total or mean TMIN43 Eq is related to CR rate. Also, higher radiation dose and smaller involved tumor area are related to higher CR rates. At 1 month follow-up 13/27 (48%) fields showed CR. At 3 months, four more CRs were noted, yielding 17/23 (74%) CR.