CA 15-3 levels high

Hello ,i hope this letters finds all of you good
August 2015,my mother was diagnosed with breast cancer stage 2B as the cancer had spread to the lymph nodes. She had a Simple Mastectomy then chemotherapy and radiation therapy.The cancer was hormone positive and the doctors told us that it was a good thing as it was easier to control the hormones to prevent the cancer return so they prescribed to my mother Nolvadex for the next 5 year. Everything was good ,she did regulars check and everything was good .The Ca 15-3 test levels were good for a year.October 2016 when she was doing some tests the CA 15-3 levels were 105 U/mL and doctors were shocked by it because everything else ,the echos mammography test were good .Surprisingly her triglycerides levels were very high and the doctors said that it was the reason for such high CA 125 levels (i note July 2016 her CA 15-3 levels were 20 U/ml).So my question is :what could be the cause of such rapid increase of CA 15-3 levels,could it really be because of triglycerides or it is a direct indicator of the return of cancer . Please,please,please respond to my letter as soon as you can because my mother is devastated.
god bless you