A mother of a 12-year-old girl was asking me this question the other day.
"Should I give my daughter cervical cancer vaccine?"
I was not prepared for the question. Though I know such a vaccine is available I have not studied it in detail. So my answer was little bit evasive.
' It is a new vaccine. Needs to be studied more .........."
I was curious why she asked the question.
"My sister who lives in USA gave her daughter the vaccine. I was wondering whether I should give it to my daughter too."
I realized that I would be asked similar questions again and again as the vaccine has been launched in India. More over I may have to take a decision about it personally since I have a daughter of about same age.
This post is an attempt by me to answer the question raised by that mother after considering all the facts available at present.
What is cervical cancer?
The cervix is another name for the neck of the womb. It is the opening to the womb from the vagina. It is really a strong muscle. Normally it is quite tightly shut, but during labour it opens up to let the baby out.
The cervix has a layer of skin-like cells on its outer surface. When these cells become cancerous it is called squamous cell cervical cancer.
There are glandular cells lining the inside of the cervix. The glandular cells produce mucus. Cancer of these cells is called adenocarcinoma of the cervix.
The area where cervical cells are most likely to become cancerous is called the transformation zone. It is the area around the opening of the cervix that leads on to the narrow passageway running up into the womb.
What causes cervical cancer?
Human papilloma virus or HPV is the major cause of cervical cancer. There are many different types of HPV. It is sometimes called the genital wart virus as some types of HPV cause genital warts. In fact, the types that cause warts are not the types that cause cervical cancer. But there are other types of HPV that are considered 'high risk' for cancer of the cervix. HPV is passed on from person to another through sexual contact.
Women who get cervical cancer have had past infections with HPV. High risk types of HPV can cause changes in the cells covering the cervix that make them more likely to become cancerous in time. It is said that around 50 to 80 % of women get infected with HPV some time in their lifetime.
Most people with HPV do not develop symptoms or health problems from it. In 90% of cases, the body’s immune system clears HPV naturally within two years.
But most women infected with these viruses do NOT develop cervical cancer. So other factors must also be needed for someone with HPV infection to develop cervical cancer.
HPV is passed on through genital contact, most often during vaginal and anal sex. HPV may also be passed on during oral sex and genital-to-genital contact. HPV can be passed on between straight and same-sex partners—even when the infected partner has no signs or symptoms.
A person can have HPV even if years have passed since he or she had sexual contact with an infected person. Most infected persons do not realize they are infected or that they are passing the virus on to a sex partner. It is also possible to get more than one type of HPV.
HPV can cause normal cells on infected skin to turn abnormal. Most of the time, you cannot see or feel these cell changes. In most cases, the body fights off HPV naturally and the infected cells then go back to normal. But in cases when the body does not fight off HPV, HPV can cause visible changes in the form of genital warts or cancer. Warts can appear within weeks or months after getting HPV. Cancer often takes years to develop after getting HPV.
Other risk factors for Cervical Cancer
Women who smoke are more likely to get cervical cancer than those who do not. Taking the birth control pill could increase a woman’s risk of cervical cancer. It is not clear why this is. Women with a weakened immune system are also more likely to get cervical cancer, as are those who have had a large number of children.
Preventive measures against HPV infection
For those who choose to be sexually active, condoms may lower the risk of HPV. To be most effective, they should be used with every sex act, from start to finish. Condoms may also lower the risk of developing HPV-related diseases, such as genital warts and cervical cancer. But HPV can infect areas that are not covered by a condom - so condoms may not fully protect against HPV.
People can also lower their chances of getting HPV by starting sexual activity at a later age, being in a faithful relationship with one partner; limiting their number of sex partners; and choosing a partner who has had no or few prior sex partners. But even people with only one lifetime sex partner can get HPV. And it may not be possible to determine if a partner who has been sexually active in the past is currently infected. That's why the only sure way to prevent HPV is to avoid all sexual activity.
Preventive measures against Cervical Cancer
Cervical screening is very important because we can stop cervical cancer from developing in the first place. This is one of the few cancers that are preventable because pre-cancerous cell changes can be picked up before they have a chance to develop into a full-blown cancer.
The screening test is often called a cervical smear. A nurse or doctor takes a small sample of cells from the surface of your cervix and spread straight onto a glass slide or put into a liquid. When it reaches the lab, your sample is put under a microscope. The cells are examined and any abnormal ones reported.
The smear test picks up pre-cancerous changes. If you have an abnormal result, it does NOT mean you have cervical cancer. But you may need further tests or treatment for an abnormal smear.
You have to be screened like this every 3 to 5 years from 25 years of age.
Vaccine against HPV
Now I come to the topic I wanted to discuss.
How good are these vaccines in preventing Cervical Cancer?
Are there any risks in taking this vaccine?
Though they are marketed as cervical cancer vaccines, they only prevent the infection of few types of HPV that are responsible for about 70% of cervical cancers. The studies that were conducted were for a period of about 2 to 3 years only. No long-term study results are available yet. Also no studies were conducted in girls less than 16 years of age. The studies had shown that the Vaccine can prevent abnormal cell changes for 2 to 3 years, but long-term effectiveness is not known.
Cervical intra epithelial neoplasia (abnormal cell growth) is graded from 1 to 3. Grade 1 indicates active HPV infection and is not considered to be pre-cancerous; current guidelines discourage treatment of this condition. Grade 2 is treated in most women but is not considered as true marker of developing cancer, as up to 40 percent of such lesions regress spontaneously; current guidelines suggest that some young women with such lesions do not need treatment. Grade 3 cervical neoplasia has the lowest likelihood of regression and the strongest potential to become cancerous.
In the HPV vaccine trials not much efficacy was reported in Grade 3 disease. This was attributed to other types of HPV, [against which we do not have vaccines] taking over and producing Cancer.
Though 3 doses are currently recommended whether there is a need for booster dose is not known
In conclusion the overall efficacy is only about 17 to 20 %.
Even after taking the vaccine the Women should undergo routine screening and safe sex practices to get maximum benefits.
Although it was licensed for use in the United States in June 2006, the first phase 3 trials of the HPV vaccine with clinically relevant end points — cervical intraepithelial neoplasia grades 2 and 3 (CIN 2/3) — were not reported until May 2007,
Why the US FDA and CDC was in such a hurry to give approval to this vaccine?
The editorial in the New England Journal of Medicine [NEJM] said
The vaccine was highly successful in reducing the incidence of precancerous cervical lesions caused by HPV-16 and HPV-18, but a number of critical questions remained unanswered.
For instance, will the vaccine ultimately prevent not only cervical lesions, but also cervical cancer and death?
How long will protection conferred by the vaccine last?
Since most HPV infections are easily cleared by the immune system, how will vaccination affect natural immunity against HPV, and with what implications?
How will the vaccine affect preadolescent girls, given that the only trials conducted in this cohort have been on the immune response? ......
.....In the meantime, there has been pressure on policymakers worldwide to introduce the HPV vaccine in national or statewide vaccination programs. How can policymakers make rational choices about the introduction of medical interventions that might do good in the future, but for which evidence is insufficient, especially since we will not know for many years whether the intervention will work or — in the worst case — do harm?
....... serious questions regarding the overall effectiveness of the vaccine in the protection against cervical cancer remained to be answered, and more long-term studies were called for before large-scale vaccination programs could be recommended.
Is the vaccine safe?
.Even though most of the reported adverse events were not serious, there were some reports of hypersensitivity reactions including anaphylaxis, Guillain-Barré syndrome, transverse myelitis, pancreatitis, and venous thromboembolic events. The editorial in the JAMA [Journal of American Medical Association] says, "it is also difficult to conclude that a serious event is not caused by the vaccine". That means the safety is not fully assured.
Should I recommend the HPV Vaccine?
The JAMA editorial says
When do physicians know enough about the beneficial effects of a new medical intervention to start recommending or using it? When is the available information about harmful adverse effects sufficient to conclude that the risks outweigh the potential benefits? If in doubt, should physicians err on the side of caution or on the side of hope? These questions are at the core of all medical decision making. It is a complicated process because medical knowledge is typically incomplete and ambiguous. It is especially complex to make decisions about whether to use drugs that may prevent disease in the future, particularly when these drugs are given to otherwise healthy individuals. Vaccines are examples of such drugs, and the human papillomavirus (HPV) vaccine is a case in point.
........Whether a risk is worth taking depends not only on the absolute risk, but on the relationship between the potential risk and the potential benefit. If the potential benefits are substantial, most individuals would be willing to accept the risks. But the net benefit of the HPV vaccine to a woman is uncertain. Even if persistently infected with HPV, a woman most likely will not develop cancer if she is regularly screened. So rationally she should be willing to accept only a small risk of harmful effects from the vaccine.
When weighing evidence about risks and benefits, it is also appropriate to ask who takes the risk, and who gets the benefit. Patients and the public logically expect that only medical and scientific evidence is put on the balance. If other matters weigh in, such as profit for a company or financial or professional gains for physicians or groups of physicians, the balance is easily skewed. The balance will also tilt if the adverse events are not calculated correctly.
My conclusion is like this.
I will not recommend HPV Vaccine with the present available scientific evidence due to the fact that the efficacy in preventing invasive cervical cancer is not much and there is a small but considerable risk of adverse events.
Even though India reports more than 70000 deaths yearly due to cervical cancer,this coslty vaccine [around 10000 Rs for 3 shots] is highly unlikely to make any change in incidence of Cervical cancer in India due low efficacy and prohibitive cost.
Links and references
Controversy on cancer vaccine
more on cervical cancer