My mother was diagnosed with breast cancer in 2011. She used to have unbearable pain around her waist region. Her CA-15.3 levels were found to be above 500. So after intensive chemotherapy and radiation therapy, she got well. She has been under a well reputed oncologist. Though she got well, the pain returned without a definite frequency. But we can say she was well. She is under regular check ups and tests to confirm that well being. And her CA-15.3 levels were brought down too. But lately, during a period of 6 months the level has been rising. Like 2 months ago it was 56 from 47, and now this month it was found to be 66. She also has several leg pains sometimes, though after taking a medicine that reduces. She stays good for someday, but then again the pain increases. And the rising CA-15.3 level is adding to the worry. Can you please help me out providing some light on that matter? Is there something to worry about? Thank you.