Even though her Pap tests had come back normal, McKinney's HPV test was positive.

NPR: Detecting High-Risk HPV in Older Women

It turns out that cells can flake off of tumors in the ovaries or the lining of the uterus, and float down to rest in the cervix, where Pap tests are performed.

NPR: Retooling Pap Test To Spot More Kinds Of Cancer

Although vaccines against some of the most dangerous HPV strains have been approved for girls ages 13 to 26, the vaccines are expensive and routine Pap tests are still necessary to pick up cervical cancers.

CNN: Circumcision reduces risk of herpes and HPV infection

It suggests the test is far more likely to give 'false-positive' readings from cervical, or Pap, tests, than pick up early signs of cancer.

BBC: Annual post-menopause smears 'unnecessary'

Even a casual reader of newspapers must be aware that there is considerable debate about when and how often people should get mammograms, Pap smear tests, PSA tests, and other cancer screenings.

FORBES: Contrary To What Nicholas Kristof Tells You, Healthcare Is Not Free

Other tests -- such as a Pap smear for cervical cancer or a lymph node biopsy for lymphoma -- are also safe.

CNN: Pregnant with cancer

The list includes electrocardiograms for asymptomatic patients, imaging tests for routine back pain, and Pap smears for women younger than 21 years old.

CNN: Doctors and patients should talk more, test less