MULTIPLE FIELD HYPERTHERMIA COMBINED WITH RADIOTHERAPY IN ADVANCED-CARCINOMA OF THE BREAST

Extensive recurrences on the chest wall of advanced carcinoma of the b reast in 20 patients were treated with multiple field patchwork hypert hermia combined with radiation therapy between 1987-1991. The objectiv e of the study was to evaluate the feasibility, tumour response and co mplications of treating extensive lesions with multiple, overlapping f ields of hyperthermia. All lesions were diffuse encompassing up to 290 0 cm(2) with or without multiple nodules less than or equal to 3 cm de ep. All lesions had failed previous therapy with all but three failing previous radiotherapy. Hyperthermia consisted of 282 hyperthermia app licator fields and 357 hyperthermia treatments with external 915 MHz m icrowaves using commercially available applicators. Hyperthermia appli cator fields were defined by the surface 50% SAR distribution of a par ticular applicator, and hyperthermia fields were abutted to cover the entire tumour bearing area. Radiation therapy consisted of 81 fields t o a mean dose of 40 +/- 1 Gy (SE), 88% of fields received between 30 a nd 50 Gy. The equivalent total dose was 42 +/- 1 Gy, based on the line ar-quadratic model and alpha/beta = 25 (Fowler 1989). Overlapping hype rthermia fields were separated by an interval of at least three days. Up to four heat sessions per week were required to cover the entire tu mour in a rotating fashion. The hyperthermia treatment time was 60 min . Hyperthermia treatments were continued for the duration of radiation therapy. Each hyperthermia applicator field was heated at least once. Patients were exposed to a mean of 14 +/- 3 hyperthermia applicator f ields (range of 3-46 fields) and a mean of 18 +/- 3 hyperthermia treat ments (range of 6-61) delivered over a mean of 7.5 +/- 0.9 weeks (rang e of 3-17 weeks). Each field was heated an average of 1.3 times. The t umour complete response rate was 95% with a recurrence rate of 5%. Nev ertheless, the mean survival of patients with a complete response was only 10.8 +/- 1.7 months (range of 2-28 months) because of the systemi c tumour burden existing outside of the treated fields in these patien ts. Neither complete response, local control nor survival after thermo radiotherapy correlated with the disease free interval between initial mastectomy and recurrence. There was no evidence of increased thermal damage to skin nor evidence of tumour recurrence at junctions of hype rthermia field overlap. It is concluded that recurrent advanced carcin oma of the breast presenting as extensive, diffuse lesions on the ches t wall can be treated as effectively with multiple field patchwork the rmoradiotherapy as can nodular lesions treated with single hyperthermi a fields.