Long-duration, mild whole body hyperthermia with cisplatin: Tumour response and kinetics of apoptosis and necrosis in a metastatic rat mammary adenocarcinoma

Abstract

This study examines antitumour effect and induction of apoptosis and necrosis after treatment with long-duration, mild whole body hyperthermia (LL-WBH, 40.0 degrees C, for 6 h) in simultaneous combination with cisplatin (CDDP) on primary and metastatic tumour growth in a rat mammary adenocarcinoma. A significantly greater delay in primary mammary tumour growth was observed after treatment with LL-WBH + CDDP, compared to either modality alone (p < 0.05). LL-WBH alone caused a significant delay in spontaneous metastasis to the axillary lymph node (ALN) and LL-WBH + CDDP tended to further increase the delay in ALN metastasis. Survival was longest in rats receiving LL-WBH + CDDP, compared to other groups (p < 0.05). CDDP induced a peak of tumour apoptosis at 24 h after treatment beginning that was significantly greater than LL-WBH alone (p < 0.05). The peak of tumour apoptosis induced by LL-WBH + CDDP from 12 to 24 h was significantly greater than any other group (p < 0.01). These results suggest that the extent of treatment-induced apoptosis seems to correlate positively with antitumour response and the combination or LL-WBH with CDDP may lead to a promising adjuvant therapy for breast cancer.