手术后，放射疗法是治疗乳腺癌最常用的技术。在过去的几十年中，射频波高温疗法与放射疗法相结合，被用于增加癌症治疗的放射敏感性。细胞在有丝分裂周期不同阶段有不同的辐射和热敏感性。此外，电离辐射和高温疗法的热效应会影响细胞的有丝分裂周期，并部分诱导细胞周期阻滞。然而，高温疗法和放射疗法之间的时间间隔是影响高温疗法对癌细胞周期阻滞的关键因素，这之前还没有研究过。在本研究中，我们调查了高温疗法在多个选择的不同时间间隔后对MCF7癌细胞有丝分裂周期阻滞的影响，以找到并提出高温疗法和放射疗法之间适当的时间间隔。在这项实验研究中，我们使用MCF7乳腺癌细胞系来调查13.56 MHz高温疗法（在43°C温度下持续20分钟）对其细胞周期阻滞的影响。我们进行了流式细胞术，以评估高温疗法后不同时间间隔（1、6、24和48小时）的细胞种群有丝分裂相的变化。我们的流式细胞术结果表明，24个小时是对S和G2/M期细胞种群影响最显著的时间间隔。因此，24个小时的时间间隔可以被提议为高温疗法后进行联合放疗程序的最适当时间。在我们研究中调查的各种时间间隔中，24个小时的时间间隔可以被提议为高温疗法和放射疗法组合疗法治疗乳腺癌细胞的最适当时间。

After surgery, radiotherapy is the most common technique to treat breast cancer. Over the past decades, the thermal effects of radiofrequency-wave hyperthermia combined with radiotherapy have been used to increase radiosensitivity in cancer treatment. The cells have various radiation and thermal sensitivities at different stages of the mitotic cycle. Furthermore, ionizing radiation and the thermal effect of hyperthermia affect the cells' mitotic cycle and can partly induce cell cycle arrest. However, the time interval between hyperthermia and radiotherapy, as an essential factor influencing hyperthermia effect on cancer cells' cycle arrest, has not been studied before. In this study, we investigated the effect of hyperthermia on the MCF7 cancer cell cycle arrest in mitotic cycles at various selected time intervals after hyperthermia to find and propose appropriate time intervals between hyperthermia and radiotherapy.In this experimental study, we used the MCF7 breast cancer cell line to investigate the effect of 13.56 MHz hyperthermia (at a temperature of 43°C for a period of 20 min) on their cell cycle arrest. We performed the flowcytometry assay to assess the changes in the mitotic phases of the cell population at different time intervals (1, 6, 24, and 48 h) after hyperthermia.Our flowcytometry results indicated the 24-h time interval has the most significant effect on the cell population at S and G2/M phases. Therefore, the 24-h time interval can be proposed as the most appropriate time after hyperthermia for carrying out combinational radiotherapy procedure.Among various investigated time intervals examined in our research, the 24-h time interval can be proposed as the most appropriate time between hyperthermia and radiotherapy for combinational therapy of breast cancer cells.