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 second most common type of gynecological cancer in North America. 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 not found and are left untreated, they can progress to more invasive cancer of the cervix. Therefore, regular Pap test screening allows for early detection of precancerous cells and for initiation of treatment before these calls become cancerous.
Each year, it is estimated that 1,300 new cases of cervical cancer are diagnosed in Canada. Among these cases, 390 women will not survive their cancer. The lifetime probability of a Canadian woman developing cervical cancer is estimated to be 1 in 148. 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 45 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. One of the HPV vaccines in Canada can be given to boys and young men aged 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. 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 (before 18) 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 squamous cell carcinoma of the cervix.
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.
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 prolonged used of oral contraceptives (more than 10 years), a family history of cervical cancer, and history of STIs.
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.
Late symptoms can occur as the tumours grow large or invade other organs of the body: