Introduction: Breast Cancer (BC) is the most common cancer among women. Hyperthermia is a new cancer treatment modality which is used in addition to other treatments to improve patient's survival. The clinical use of Hyperthermia in the combination of radiotherapy is debatable and shows important technical challenges. But the most challenge in this case is the order of this combination. We aimed to explore that in Triple-negative breast cancer applying hyperthermia before radiotherapy is better or after it.

Methods and Material: The anti-proliferative activity of Hyperthermia alone and in combination with Radiotherapy in 4T1 balb/c triple negative breast cancer cell line was assessed by the standard 3-(4,5-dimethyl-2-thiazolyl)-2,5 diphenyl-2H-tetrazolium bromide (MTT) method. We also used Acridine Orange/ Propidium Iodide fluorescent staining for approving the inhibitory effect. We exposed the cells to 43±0.2°C for 30 minutes in a regular incubator, as Hyperthermia treatment and also exposing into 4Gy Gamma irradiation as Radiotherapy. In two modality treatments the time interval was two hours. Then the viability rates of cells were determined after 24, 48 and 72 hours.

Statistical analysis used: All data are expressed as the mean ± standard deviation. We used Kruskal-Wallis and Mann-Whitney for statistical analysis. P-values of less than 0/05 were considered to be statistically significant.

Results: The findings indicated that adding hyperthermia before Radiotherapy showed 58 ± 4.06, 60.6±2.03 and 62.4±2.5 viability rate after 24,48 and 72 hours, respectively; while applying it after Radiotherapy showed 63.4 ± 1.81, 67.2±2.2 and 62.4±2.5 viability rate after 24,48 and 72 hours.

Conclusions: It was concluded that in Triple negative breast cancer applying hyperthermia before radiotherapy is more efficient.

Note: This abstract was not presented at the conference.

Citation Format: Zahra Joveini, Zhaleh Behrouzkia, Reza Zohdi Aghdam. Hyperthermia plus radiotherapy in triple-negative breast cancer; before or after? [abstract]. In: Proceedings of the AACR International Conference: New Frontiers in Cancer Research; 2017 Jan 18-22; Cape Town, South Africa. Philadelphia (PA): AACR; Cancer Res 2017;77(22 Suppl):Abstract nr A07.