Should methotrexate be stopped prior to radiation therapy if a patient has rheumatoid arthritis?  

I have not stopped as dose of MTX for RA is low (7.5 mg) and there is data of CMF with RT for breast cancer with higher dose of MTX showing no significant increase in morbidity. 

I have to revisit Eric Hall’s radiobiology text, but I am not certain if the process of radiation sensitizing is necessarily dose dependent, because I think the mechanism of action in at least some cases is the re-positioning of cells at the most radio-sensitive phase of the cell cycle, G2/M. ...