Hereditary Cancer treatment success...?

My maternal grandfather ped away at age 54 of cancer. My maternal grandmother ped this Summer 2010 at age 68 of and ovarian cancer. My mom (age 48) was diagnosed with cancer not long after that. The cancer is in multiple places in her as well as in her lymph nodes. She is now being treated with chemo. She has a quite a history of cancer in her family. Please be honest. Does this decrease the likelihood of successful treatment??