Purpose: Breast and cervical cancers are the two most common cancers among women worldwide. Morphine is a potent analgesic for cancer pain, and radiation therapy is a conventional treatment for cancer. Unfortunately, the combined adjuvant cellular effects of morphine and ionizing radiation in cancer cells are largely unknown.
Materials and methods: In this study, we examined the effects of morphine and single radiation dose of 2 Gy on viability and survival fraction of human breast cancer cell line MDA-MB 231 and human cervical cancer cell line HeLa, by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and colony formation assays. We were also interested in evaluating these effects in human umbilical vein endothelial cells as well.
Results: We found that morphine did not have a dose- and time-dependent manner in endothelial, breast, and cervical cancer cells in vitro. It seems that pretreatment of breast and cervical cancer cells with morphine at some doses before irradiation reduces the cytotoxic effect of radiation. We also observed that endothelial cells were less sensitive than breast and cervical cancer cells to radiation or morphine + radiation. Based on the results of endothelial cells, morphine or radiation might not have a selective effect on the viability and clonogenic survival of different cell lines.
Conclusions: Our data may suggest that morphine and radiotherapy could not be administered together to breast and cervical cancer patients if additional and in vivo studies confirm our results.
Keywords: Breast cancer; cervical cancer; morphine; opioids; radiation.