My daughter was diagnosed with renal cell cancer. Is this likely to be a big problem for her?

It depends. Renal cell carcinoma is curable if it's early stage and confined to the kidney and treated with surgery. If it has spreaded beyond the kidney, there are chemotherapy treatments available to help to control the disease that have spreaded.
Surgery. If the tumor has not spread surgery is curative most of time, the stage of tumor defines the survival.
Age. If you are only 39 years old, then your daughter must be quite young. There are some unique types of renal cell cancers that preferentially occur in young patients. If not already determined, an expert pathology review may be helpful to decide if the tumor is one of these unique types. Also, wilms tumor or nephroblastoma is another tumor that occurs in young children.