For RT naive patients, radiation therapy fields included any gross disease. The entire breast or chest wall were included; regional nodes were generally treated. Typical adjuvant radiation fields for locally advanced breast cancer were used. 50 Gy in 1.8–2 Gy fractions was prescribed to areas without gross disease and a minimum of 60 Gy prescribed to gross disease. Bolus was used when there was skin involvement. Interstitial RT boosts were used to improve dose homogeneity in appropriate patients. For previously treated patients, radiation fields included gross disease plus a margin. A minimum target dose of 40 Gy was planned at 1.8–2 Gy per fractions. Bolus was generally used.
HT was delivered twice per week, immediately after RT. A minimum of 4 sessions was planned. Multiple measurement sites were made in each treatment field and intratumor measurements made if allowed the ability to place intratumorally thermistors. The goal was to deliver an intra- tumor temperature of >42.5°C for a minimum of 20 minutes and for optimally for >45 minutes. Temperature and HT length could be limited by patient comfort and/or intolerance, including pain.
Most patients had been treated with prior chemotherapy. Overall, 56.7% of patients received chemotherapy. Cisplatin-based regimens were often used for potential RT potentiation.
A complete response (CR) during treatment was observed in 52.7% and a partial response (PR) in 26.8%. A minor response was observed in 7.1% and 13.4% of patients showed no response or progressive disease. CR was significantly higher among patients who received a total median TED42.5°C ≥ 200 minutes (p = 0.002), and median TED 43°C ≥ 100 minutes (p = 0.03). Patients who initially presented with early stage (I and II) disease prior to progression of breast cancer requiring hyperthermia treatment had a higher rate of CR versus those patients who initially presented with advanced stages disease (p= 0.002).
Patients who achieved a CR were more likely to exhibit freedom of progression (79.4%) at their last follow up (p < 0.0001). 55.1% of the patients had local control, at a median follow-up of 13 months and a mean follow-up of 30 months (range: 0–182, SD: 38 months).
The median OS from treatment was 16 months (95% CI: 12–21 months), and the 1-year, 3- year, and 5-year OS were 58.35%, 29.59%, and 22.05%, respectively.
Grade 3–4 desquamation was the most commonly reported treatment-induced adverse event (24.4% of the patients). Ulceration, telangiectasia, and fibrosis were reported in 6.7%, 4.7%, and 6.3% of the patients respectively. One patient had abscess formation. Using Fisher’s exact test, there was no significant difference in Grade 3–4 adverse events among patients who had prior RT (43.8%) versus those who did not (46.3%) (p = 0.86).
Hyperthermia and radiation therapy is an effective combination in obtaining local control in a group of patients that have been historically difficult to treat by radiation. Overall survival was related to the ability to obtain local control, higher doses of radiation, and higher doses of hyperthermia.
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Scientific article publishing date 21/8/2015
Immucura identifier BSC21_037EN