Could Lack Of Energy And Tiredness Be A Symptom Of Cancer?

Hi my mom age 60 was just diagnosed with peritoneal Cancer a plum size tumor on the vaginal cuff she had this and uteran Cancer 11 yrs ago she had a full hysterectomy and had chemo 12 years later it s returned ct scan shows no signs of it spreading ThankFully !!! Next thurs she will have tumor removed and then start chemo ... She is exastued and can this tiredness be a sign/symptom of her Cancer ? Also dr didnt stage/grade this Cancer he said we don t stage reoccurring cancers thank you