Dr. Gabe Mirkin's Fitness and Health E-Zine
June 5, 2011
Many Skin Cancers and Pre-Cancers Are Caused by HPV and Sunlight
*******We have known for many years that the Human Papilloma
Virus (HPV) causes almost all warts on the skin, most head and
neck cancers, and almost all cervical cancers. *Now we find that
HPV also causes the common skin pre-cancers called actinic
keratoses, which can develop into squamous cell skin cancers that
can spread through other parts of the body (Trends in
Microbiology, January 2011). *More than 60 million Americans
suffer from actinic keratoses, scaly areas on sun-exposed skin
primarily on the face, ears, scalp, neck, and dorsal surface of
the hands.
* *Most actinic keratosis cells are infected with HPV, the
viruses that cause warts (1 - see list of references below).
Dr. Eggert Stockfleth, of the Charité Hospital in Berlin, found
specific types of HPV (21, 5, 8, 16 and 18) that convert normal
skin to the pre-cancerous actinic keratoses, which may then
progress to become squamous cell cancers (2).
* *Recent research shows that these skin pre-cancers are caused
by a combination of cumulative exposure to sunlight and HPV, which
can be acquired through sexual contact (3).
* *HOW SKIN CANCER STARTS: Chronic exposure to ultraviolet
light damages DNA in skin cells. Your immunity tries to repair
this damage, but the Human Papilloma wart viruses can prevent your
immunity from repairing the DNA. *Most of the time when your DNA is
damaged, the cells die because they have a programmable cell death
called apoptosis. However, the HPV virus prevents DNA from healing
and also prevents the programmable cell death that would have
removed the damaged cells (4). Then you develop scaly areas and
bumps on your skin called actinic keratoses. *With further exposure
to sunlight, HPV can cause these damaged cells that do not die to
develop into squamous cell skin cancers that can spread through
your body.
* *THE MORE DIFFERENT HPV VIRUSES YOU HAVE, THE MORE LIKELY YOU
ARE TO DEVELOP SKIN CANCERS. *More than 150 different types of HPV
exist. Some types of HPV (Types 8, 24 and 76) are far more likely
to cause skin cancer than others. *The ones most likely to cause
cervical cancers are types 16, 18, 52 and 59. They are also the
ones that persist the longest, and are most likely to cause
cancers and abnormal PAP smears.
*******A person acquires these viruses usually, but not always,
from a sexual contact, and then a person's immunity usually clears
the virus in six to eight months. However, the more viruses a
person picks up from other people, the more likely he or she is to
go on to suffer squamous cell skin cancers (5).
*******The more sexual partners you have, the more likely you are
to acquire and keep the cancer-causing HPV virus (6). *Men 18 to
70 years old who were free of both HIV and cancer had HPV cultures
taken every six months from several places on the penis and
scrotum. *Among the 1159 men, the incidence of new genital HPV
infection was 3.8 percent every six months. Those who had the most
sexual partners had the most HPV infections that cause cancer.
*******Positive cultures for HPV persisted for an average of 7.5
months, and for HPV 16, the type more likely to cause cancer, for
12.2 months. *The more partners a person has, the less likely he
is to clear the virus. *Older people clear HPV faster than younger
ones, probably because they have fewer new partners.
* *MOST HPV INFECTIONS GO AWAY: *If you don't acquire any of
the other 150 HPV types from additional contact, most HPV
infections appear to clear themselves without treatment (7). *
DNA tests of HPV show that 70 percent of women clear HPV infections
in their cervix and vaginas within one year, and only nine percent
continue to be infected after two years (8). *A summary of several
studies shows that 90 percent of HPV tests become negative in
about two years.
*******The current theory is that you become infected with HPV,
usually through sexual contact, and it can disappear without
treatment, as cultures fail to find it. *We do not know if the
virus really goes away, but we usually cannot find it. *However,
some people never clear the high-cancer-risk types of HPV and it
is the persistent infections that can lead to skin pre-cancers and
cancers (9).
* *ADDITIONAL EXPOSURE TO HPV: Infected people who continue to
have the most sexual contacts are the ones most likely to continue
to be infected with HPV. *Each additional sexual exposure increases
your chances for acquiring additional HPV viruses and the specific
viruses that cause cancer.
*******You can have several different HPV virus types at the same
time. *Acquiring immunity to one type of HPV does not protect you
from becoming infected with another type of HPV in the future. *
It is likely that the more HPV viruses that infect you and the
more sunlight that damages your skin, the more likely you are to
develop skin cancer.
* *HOW DO YOU GET HPV?: The most common way to acquire HPV is
through rubbing skin on skin, usually through sexual contact, but
any type of rubbing skin on skin has been associated with an
increased risk. Non-penetrating skin-on-skin contact has caused
HPV transmission even in virgins (10). *The virus has repeatedly
been found underneath the fingernails, so shaking hands can, at
least theoretically, transmit the virus (11). *Furthermore, HPV
can be transmitted non-sexually from a mother to her child (12).
HPV was found in up to 50 percent of pubic and anal hairs removed
from patients with genital warts (13).
* *CONDOMS: Condoms do not offer complete protection against
HPV since any skin-to-skin contact can result in transmission of
the virus (14). The virus can also pass around condoms in body
fluids, such as saliva, semen and vaginal secretions.
* *NEW SEXUAL PARTNERS: You are most likely to acquire HPV from
a new sexual partner, rather than an old one, as healthy people
usually clear the virus from their bodies in six to eight months.
Each new partner can give you new HPV infections and the more HPV
viruses you have at one time, the more likely HPV is to persist
and the greater your risk for developing cancers.
* *PUBLIC PLACES: It is extremely unlikely that you will pick
up HPV from a public shower, sauna, or wet seat. Samples were
collected with a toothbrush from the floor and seat surfaces of
bathing resorts, showers, swimming pools, saunas, bathrooms and
dressing rooms. No HPV DNA-positive samples were found (15)
* *RISK FACTORS FOR ORAL CANCERS: You are five times more likely
to suffer oral cancer from HPV if you have had more than five
oral-sex partners in their lifetime. *You increase risk for HPV with
*increasing numbers of sexual partners,
*engaging in casual sex,
*having an early age at first intercourse, and
*using condoms infrequently (16).
* *COFACTORS INCREASE RISK FOR CANCER FROM HPV: *Many things
you do increase your risk for cancer and the more risk factors you
have, the greater your risk. Avoiding these risk factors after you
are diagnosed with a cancer can increase your chance for a cure.
********Smoking and being infected with HPV both cause fatal
squamous cell cancers of the head and neck. *A study from the
University of Michigan shows that smokers who have an HPV-linked
cancer are six times more likely to have a recurrence than those
who have never smoked, and two-thirds of patients with HPV-linked
tumors were current or former tobacco users (17). *Among those with
HPV-linked tumors, six percent of those who never smoked had
recurrences, compared to 19 percent of those who had smoked in the
past and 35 percent of current smokers. *Almost all cases of
cervical cancers are caused by HPV, but only one woman of 250
infected with HPV develops cervical cancer. If you are infected
with HPV and smoke, you increase your chances of developing cervical
cancer 15 times (18).
*******Lifestyle factors that are associated with increased
cancer risk (as well as heart attack risk) include: smoking,
taking more than two alcoholic drinks per day, being overweight,
not exercising, not eating enough fruits and vegetables, eating
too much saturated fat from mammals, eating burnt food (PAHs and
HCAs), lack of vitamin D, lack of sunlight, and anything that
increases risk for diabetes. *Other risk factors include
promiscuous behavior that exposes you to hepatitis B and C
viruses, HPV, human immunodeficiency virus (HIV), Helicobacter
pylori (H. pylori), Human T-cell leukemia/lymphoma virus (HTLV-1),
Epstein-Barr virus (EBV), or Human herpes virus 8 (HHV8); working
in jobs that expose you to radiation, chemicals such as asbestos,
benzene, benzidine, cadmium, nickel, or vinyl chloride, certain
metals, pesticides or solvents; taking certain medications and
hormones; repeated exposure of your skin to excess sunlight or
getting too many X rays.
* *TREATMENT OF GENITAL WARTS: Virtually all genital warts are
caused by HPV. *Doctors treat genital warts by burning, freezing,
lasering, scraping, or removing them surgically. *They use
chemicals to sensitize skin to sunlight and then use light to burn
the warts off. *They even peel them off. *However, warts often
return after all destructive procedures, so I usually recommend
*Fluoro-uracil cream (an anti-cancer drug),
*Imiquimod cream (a chemical that increases your immunity), or
*Diclofenac sodium gel (a drug that blunts your immune reaction).
* *TREATMENT FOR ACTINIC KERATOSES: *I think that the most
effective treatment for actinic keratoses is to use a generic
version of imiquimod cream (brand name Aldara). *It enhances your
immunity so it can more effectively kill HPV. *It is applied twice
a week for 16 weeks, left on the skin for about eight hours and
then washed off.
*******Current treatment by most dermatologists is to destroy the
lesions of actinic keratoses with liquid nitrogen or
electrocautery. *Surgery is rarely needed. However, once an actinic
keratosis becomes a squamous cell carcinoma, surgeons usually
remove the entire cancer. A pathologist usually checks the removed
tissue to see that there is a 360-degree margin of non-cancerous
skin around the removed cancer.
References:
1. New England Journal of Medicine, May 15, 2003
2. Disease Markers, April 2007
3. Expert Review of Dermatology, April 2010
4. Cancer Detection and Prevention, June 2001
5. BMJ. 2010;341:c2986
6. The Lancet, published online March 1, 2011
7. Am J of Ob and Gyn, 2000;183(3): 561-567
8. NEJM, 1998;338(7):423-428
9. Trends in Microbiology, 2011(Jan);19(1):33-39
10. Scand J Infect Dis 1996;28(3):243-6
11. Sexually Transmitted Infections 1999 Oct;75(5):317-9
12. J Med Virol 1998 Nov;56(3):210-6
13. J Clin Microbiol. 1999 Jul;37(7):2270-3
14. Am J Epidemiol 2003 Feb 1;157(3):218-26
15. Rev Med Virol 1999 Jan-Mar;9(1):15-21
16. NEJM May 9, 2007
17. Clinical Cancer Research, February, 2010
18. Cancer Epidemiology, Biomarkers & Prevention, November 2006
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Gabe Mirkin, M.D.
10901 Connecticut Avenue, Kensington MD 20895, USA
