Making
the Link:
HPV and Cervical Cancer |
Human papillomavirus (HPV) has been around for thousands of years.
Early Greek and Roman medical records describe genital warts associated
with sexual activity.19 In the
mid-19th century, scientists reported that cervical cancer never
occurred in celibate nuns or virgins, an indication of its relationship
to sexual activity.20 Papillomavirus
was initially isolated from rabbits in 1933.21–22
Two years later, it was discovered that the virus had the potential
to cause malignancies.21,23 Squamous
cells that developed from HPV lesions were noted in 1956.24
The link between HPV and cervical cancer was first suggested in
1975.25
Today, more than 100 HPV types have been identified and numbered
and categorized as low- or high-risk in relation to their potential
to cause cancer. More than 30 types can infect the genital area.
Of these, low-risk types 6 and 11 are associated with external genital
warts but do not cause cervical cancer. Types 16, 18, 26, 31, 33,
35, 39, 45, 51, 52, 56, 58, 59, 66, 68, 73, and 82 are considered
high-risk types. In most countries, including the United States,
HPV 16 alone accounts for more than 50–60 percent of cervical
cancer cases, followed by HPV 18 (10–12 percent) and HPV types
31 and 45 (4–5 percent each).26 |
Today, genital infection with HPV is the most common sexually transmitted
viral infection in the United States.13
An estimated 6.2 million new genital HPV infections occur each year.14
Overall, about 75 percent of the US adult population has been exposed to
HPV.15 By the age of 50, it is estimated
that 80 percent of women have contracted HPV, and it is likely that similar
rates of infection would be found in men if good HPV testing methods were
available for males.16
“It is now agreed that 100 percent of cervical cancer is caused
by HPV,” says Saslow. “The actual number is about 99.7 percent,
but it is thought that the 0.3 percent is due to failure of testing rather
than the absence of HPV.” The vast majority of genital HPV infections
cause no symptoms and go away on their own. But genital HPV remains a
public health concern because persistent infection with certain high-risk
types can cause cervical cancer.17–18
“Genital HPV infection is especially common among sexually active
young women [less than 25 years of age], with prevalence decreasing with
older age,” said CDC’s Lawson. “The higher rates in
younger women appear to be related to transmission of new infection during
the early years of sexual activity, with infection clearing over time
in most women.”
The lowest rate of HPV detection is in women aged 30–55. There
are few data on women older than 65, and even fewer on men. Experts believe
that men probably have infection rates as high as women’s, but HPV
is harder to detect in men.
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