Could Thickening Of Endometrium Be A Matter Of Concern?

Hello my mom is 62 yrs old and had noticed she would have vaginal bleeding when she went to the restroom. She went to the gynecologist office and was told she has a 1cm nogule representing a polyp, representing blood clot, also her endometrium is thickened. Can you please tell me how serious this is. My family and I are scared and the drs office doesn t have an appt to biopsy this until April 21,2015 So we have to wait until then for the results. They mentioned R/O cancer. Can you please let me know. Thank you.