Diagnosed with a heart fibro-elastoma , 50-50 chances it is cancer, how to take this thing forward?

My mother was diagnosed with a fibro-elastoma (1.5cmx 2cm) in PML of heart about an year ago. It was an accidental discovery during the clearance for surgical removal of a lipoma in left underarm. She had no symptoms except for prolonged mild fever which has stopped since the last 3 months. Recently a growth in the tumor (about 0.5cm) was reported through echo. The doctor advised Cardiac MRI.
The Cardiac MRI gave a different picture.

The size is about 2.5 to 3 cm (about 0.5cm growth in an year)
The tumor is not attached to any valve, instead it’s on the inner side of heart chamber (no damage to the heart wall)
The radiologist says its giving a very high contrast which means its vascular
They say it could be connected to the lipoma in her underarm(the lipoma was diagnosed through biopsy an year ago)
They say there is a 50-50 chance that the heart tumor is cancerous, and to confirm a biopsy will be done of the tumor which requires open heart surgery
We need your advise on how to take this thing forward. The tumor has been there for about 1.5 hear without a growth like that of cancer and my mother is normal without any symptoms except for Diabetes, high blood pressure and plus she is over weight .

Your help in this regard will be highly appreciated

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