Q: I am a 37-year old woman whose grandmother and aunt were recently diagnosed with cervical cancer. In addition to my yearly Pap smears, are there any steps I should be taking to prevent this from happening to me?
A: Cervical cancer is not generally thought to be a genetically linked disease. It is most often caused by a family of viruses collectively known as the human papillomavirus (HPV). HPV is extremely common in the human population; it is believed that approximately 80 percent of women will have been infected with HPV by age 50. HPV is transmitted sexually, so although most studies of HPV infection are in women, it is believed that men are infected at similar rates. Although the prevalence of infection in the human population is quite high, only some infected women will develop cervical cancer. Science is currently unable to predict which women with HPV will develop changes on the cervix that will lead to cancer.
Pap smear screening is probably the single most important preventative measure that a woman can take to prevent the development of cervical cancer. This cancer is especially amenable to screening as it has a long pre-cancerous stage, called dysplasia, which may last five to 10 years. The Pap smear is designed to detect these changes on the cervix so that they may be treated, preventing any progression to cervical cancer. The Pap smear is a definite proven commodityover the past 40 years, with the acceptance of annual Pap smears by American women, the incidence of cervical cancer in the United States has declined by 75 percent. This is in contrast to the high rates of cervical cancer in countries where Pap smears are not available on a wide scale. Their cervical cancer rates are similar to that of the United States in the 1950s.
It is recommended that a woman starts annual Pap smear screening within three years of initial sexual activity or by age 21; whichever comes first. The Pap smear is incredibly reliable in detecting pre-cancerous changes on the cervix, provided women are screened yearly. Unfortunately, most women diagnosed with cervical cancer in the United States have not had a Pap smear in the three to five years prior to diagnosis.
In addition, since 2006, a vaccine has been available to prevent infection with certain types of HPV. This vaccine, called Gardisil, protects a woman from four types of HPV: types 6, 11, 16, and 18. Types 6 and 11 do not cause cervical cancer but are responsible for 90 percent of genital warts, while types 16 and 18 account for 70 percent of all cervical cancer cases . For the vaccine to work, it must be administered before the woman is infected with HPV through sexual intercourse. Thus, although the vaccine is approved for females ages 9 through 26, it is recommended for all girls ages 11 and 12. The vaccine is very effective; more than 90 percent of girls and women vaccinated are protected from infection with HPV and from developing pre-cancerous changes on the cervix. It's important to note that the vaccine does not contain the live virus; thus, it is not possible to become infected with HPV by being vaccinated. This vaccine is potentially the most exciting development (yet? of the century?) in the fight against cervical cancer. However, as the vaccine only protects against the virus types that cause 70 percent of all cervical cancer, it's still essential to continue annual Pap smear screening even after one has received the vaccination.
Lastly, as HPV is transmitted sexually, decreasing the potential for infection may theoretically decrease the chance that a woman will develop cervical cancer. Consistent use of condoms has been shown to decrease infection rates of HPV. Also, as rates of cervical cancer are higher in smokers, quitting the use of tobacco products may also decrease the risk of developing cervical cancer. In fact, nicotine by-products have actually been found in the cervical mucus of female smokers. It is thought that the noxious by-products of smoking may make it easier for the HPV virus to infect the cells of the cervix.
Dr. Tri Anh Dinh is a gynecologic oncologist at the Methodist Hospital in Houston and an assistant professor of Obstetrics and Gynecology at Weill Medical College of Cornell University. He earned his medical degree and interned at Baylor College of Medicine; completed his residency at the University of Texas Medical Branch at Galveston; and did his fellowship in gynecologic oncology at the Massachusetts General Hospital. Dinh is an active member of numerous professional organizations, including the American College of Obstetricians and Gynecologists, the Society of Gynecologic Oncologists, and the American Society for Colposcopy and Cervical Pathology.
