子宮頸癌
HPV is passed through skin to skin contact; sex does not have to occur, although it is a common way for it to spread. It takes an average of a year, but can take up to four years, for a person's immune system to control the initial infection. Screening during this period may show this immune reaction and repair as mild abnormalities, which are usually not associated with cervical cancer, but could cause the patient stress and result in further tests and possible treatment. Cervical cancer usually takes time to develop, so delaying the start of screening a few years poses little risk of missing a potentially precancerous lesion. For instance, screening people under age 25 does not decrease cancer rates under age 30.