Cervical cancer affects the cervix, which is a part of the female reproductive system. The cervix is the lowest portion of a women's uterus (womb) and is located at the top of the vagina. The cervix is made up of cells which can change from being healthy to abnormal.
Cancer refers to a class of diseases in which abnormal cells grow without control. The term tumour or neoplasm refers to an abnormal growth of cells. Tumours can either be noncancerous (benign) or cancerous (malignant). A benign tumour does not spread to surrounding tissues or organs and usually does not come back after it has been removed. On the other hand, a malignant tumour can spread (e.g., from the cervix) and invade other tissues or organs in the body.
Cervical cancer is the third most common type of gynecological cancer in North America and the fourth most common cancer in women worldwide. The incidence of cervical cancer has declined dramatically since the 1950s. The Pap test screening (also known as Pap smear) was the major contributing factor to this decline. The Pap test detects cell changes in the cervix.
As discussed above, some of these changes are noncancerous, but some cells may become precancerous. If precancerous cells are left untreated, they can progress to invasive cancer of the cervix. Regular Pap test screening allows for early detection of precancerous cells and for initiation of treatment before these calls become cancerous.
In Canada it is estimated that approximately 1,350 new cases of cervical cancer are diagnosed each year. About 400 women will die from cervical cancer each year. The lifetime probability of a Canadian woman developing cervical cancer is estimated to be 1 in 168. Fortunately, almost all cervical cancer can be cured when diagnosed and treated at an early stage. The cure rate for stage 1 cervical cancer (cancer limited to the cervix) is 80% to 90%.
Since some types of human papillomavirus (HPV) can cause cancer of the cervix, HPV vaccination has been made available in Canada since 2006. It is recommended that females between the ages of 9 and 26 receive the HPV vaccine to protect them from strains of the HPV virus responsible for approximately 70% of cervical cancers.
Although males cannot get cervical cancer, vaccinating boys and young men against HPV is still beneficial. It helps prevent the spread of HPV and also helps reduce their risk of anal cancer and genital warts, which are also caused by HPV. Vaccination is recommended for males between the ages of 9 to 26.
For the most part, cervical cancer can be prevented and cured when detected in the early stages.
So far, it is not fully understood what causes cells to become abnormal and to grow without control. Some factors have been observed to increase the risk of developing cancer of the cervix.
HPV: The most important risk factor is the infection of the cervix with HPV. HPV is one of the most common sexually transmitted infections (STIs). It is estimated that 75% of individuals who are sexually active will have at least one HPV infection in their lifetime, many of which are without symptoms. While some types of HPV cause genital warts, other strains of the virus can infect the cervix and then cause abnormal changes within the cells that may slowly progress to cancer. It is important to note that most women diagnosed with cervical cancer had a previous HPV infection; however, not all women with an HPV infection will develop this type of cancer.
Sexual activity: Becoming sexually active at an early age is linked to a higher risk of cervical cancer. Also, certain sexual behaviours (such as having multiple sex partners and partners who have multiple partners) can increase a woman's likelihood of becoming infected with HPV, thereby increasing the risk of cervical cancer.
Smoking: People who smoke are at higher risk of cervical cancer, as well as other cancers. Both tobacco smoking and exposure to secondhand smoke (environmental tobacco smoke) have been associated with the development of cervical cancer. In fact, the risk increases with the length of time a woman smokes and the number of cigarettes consumed per day.
Weakened immune system: Our immune system helps our body fight infections. Therefore, medications and diseases that diminish the immune system can increase a woman's risk of HPV infections, thereby increasing the risk of cervical cancer. Examples of medications that suppress the immune systems are corticosteroids (used over a long period of time) and chemotherapy drugs. Women infected with the human immunodeficiency virus (HIV) have an increased risk of developing precancerous cervical changes with an HPV infection.
Diethylstilbestrol (DES): DES was a form of estrogen used during pregnancy between 1940 and 1971. Some studies have suggested that DES-exposed daughters may be at increased risk of developing precancerous cervical cancer and clear-cell adenocarcinoma of the cervix and vagina.
Age: Most cases of cervical cancer tend to occur in women younger than 50 years of age.
Socioeconomic status: Women with lower incomes are at higher risk of developing cervical cancer because they are less likely to receive regular Pap test screenings.
Oral contraceptives: Using birth control pills for a long time (for example, more than 10 years) increases the risk of cervical cancer in women with an HPV infection. This risk decreases once the pill is stopped.
Multiple births: Women who have given birth multiple times are at increased risk of cervical cancer, with the risk increasing as the number of births increase.
Other risk factors: Other possible factors have been associated with increased risk of cervical cancer. However, there is currently not enough evidence to consider them as main risk factors. These factors include having a family history of cervical cancer or a history of sexually transmitted infections.
Symptoms and Complications
In the early stages of cervical cancer, the woman may or may not experience symptoms. It is important to note that some symptoms of cervical cancer can also be caused by other health conditions.
Possible early symptoms may include:
- abnormal vaginal bleeding or spotting between periods
- pain during sexual intercourse or bleeding after intercourse
- clear, watery, or foul-smelling discharge from the vagina
- increased amount of vaginal discharge
Late symptoms can occur as the tumours grow large or invade other organs of the body:
- pelvic or back pain
- urine leakage (incontinence) or blood in the urine (hematuria)
- weight loss
- appetite loss or anorexia
- shortness of breath
- anemia (causing lack of energy and shortness of breath)
- blood in the stool
Making the Diagnosis
The Pap test is the main tool used to screen for cervical cancer. It is used to detect cancer or precancerous cells that may lead to cancer. This test was named after its inventor, George Papanicolaou.
The Pap test is a quick and simple procedure. Using a small brush or spatula, the doctor scrapes and removes some cells from the surface of the cervix. The test does not usually cause any pain. The cells are then examined for their appearance in a laboratory.
In the event that the Pap test shows a change or abnormalities in the cervical cells, follow-up tests or procedures may be done. Your doctor will advise which of the following tests or procedures are most suitable for you:
- Another Pap test in several months to see if there are further changes.
- HPV test may be done in combination with the Pap test to screen for cervical cancer or as a follow-up test after an abnormal Pap test result. Since the majority of cervical cancer begins with an HPV infection, this test allows for the detection of the presence of the virus in cervical cells. More specifically, the HPV test determines whether the woman is infected by a type of HPV virus that can cause cervical cancer.
- Colposcopy involves using a colposcope (an instrument with a light and magnifying lens) to examine the cervix. A dye is applied to the area to make the abnormalities more visible.
- Biopsy involves the removal of small amounts of tissue so that it can be examined in a laboratory to confirm whether the cervical cells are benign, precancerous, or cancerous.
Currently in Canada, it is recommended that women between the ages of 25 and 69 undergo regular cervical screening every 3 years. However, there may be differences in recommendation depending on the screening guidelines in your province or territory and your previous test results. Women who are considered at high risk of developing cervical cancer may require more frequent screenings. Ask your doctor how often and when you should be tested.
Treatment and Prevention
Treatment options for cervical cancer include surgery, radiation therapy, and chemotherapy.
Treatment decisions are made by an oncologist (a doctor specializing in cancer) based on the following factors: size of the tumour, stage of the cancer (severity of the precancerous changes or presence of cancerous changes), the woman's individual factors (e.g., age, whether the woman wants children), the woman's overall health, and prior treatment if any. The oncologist will discuss the most suitable treatment options with the person.
- Cryosurgery is a procedure that destroys abnormal cells by freezing them with liquid nitrogen. This type of surgery is usually done to treat precancerous changes of the cervix.
- Laser surgery employs a high-energy beam of light to destroy abnormal cells. It is done to remove precancerous or cancerous cells. Laser surgery is usually used when the affected area of the cervix cannot be reached by cryosurgery.
- Loop electrosurgical excision uses a fine wire loop electrode to remove affected lesion. It is done under local anesthesia.
- Hysterectomy refers to the surgical removal of the uterus to treat more invasive cervical cancer (larger spread or tumour sizes). Other organs, such as the ovaries, fallopian tubes, lymph nodes, and parts of the vagina, may also be removed at the same time. There are different types of hysterectomy:
- total hysterectomy: removal of the cervix and the uterus
- radical hysterectomy: removal of the cervix, uterus, upper part of the vagina, some supporting tissues, and regional lymph nodes
Radiation therapy refers to the use of high-energy rays, particles, or radioactive materials to destroy cancer cells in a localized area of the body. The goal of radiation therapy is to kill the cancer cells while minimizing the exposure of normal cells to radiation.
Chemotherapy may be used in combination with radiation therapy. Chemotherapy refers to the use of one or more anticancer medications that prevent the cancer cells from growing and reproducing. It can be used to treat metastatic (spreading to other organs) cancer and recurrent tumours. Currently, when radiation therapy is used as primary treatment for cancer of the cervix, chemotherapy is added to make the radiation more effective.
Women can minimize their risk of developing cervical cancer by reducing their risk of HPV infection. The virus is most commonly transmitted via sexual contact and intercourse. Since most HPV infections do not cause any symptoms, it is not possible to know for certain whether you or your partner is infected with HPV. Refraining from genital contact with an infected person or using a condom will reduce the risk of HPV infection. It is important to note that condoms are not 100% effective because they only protect the covered area. Other forms of contraceptives and barriers such as birth control pills, diaphragms, and intrauterine devices (IUDs) do not protect the woman against HPV infection.
If a woman smokes, quitting also reduces her chance of developing cervical cancer.
Another effective way to prevent cervical cancer is through vaccination against HPV. Since the vaccines are most effective in females who have not yet been exposed to HPV, it is recommended that females receive the vaccine before they become sexually active. But women who are already sexually active can also benefit from the vaccine if they have not yet contracted the strains of HPV included in the vaccine.
Since the HPV vaccine does not offer protection against all types of HPV that can cause cervical cancer, regular Pap test screening remains essential in preventing disease caused by HPV infection.
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