A 68-year-old G2P2 woman who has recently moved in with her daughter (a long-standing patient of yours) comes in for a health maintenance examination. A vaginal hysterectomy was done in her fifties for uterine prolapse. She is not sure if her ovaries were removed. She has never had an abnormal mammogram or Pap test and has had yearly exams. She stopped hormone replacement therapy 10 years ago. She was recently widowed after being married for 50 years. She does not smoke or drink. Her diabetes is well-controlled with Metformin; she takes a daily baby aspirin and is on a lipid-lowering agent. On examination, she is a thin elderly woman with a dowager's hump. Her breast exam is unremarkable. Her lower genital tract is notable for atrophy. No masses are noted on bimanual and recto-vaginal exam. A fecal occult blood test is negative. Which of the following tests is not necessary?