cervical cancer
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Cervical cancer describes any malignant tumor that originates in the cells of the cervix. Part of the female reproductive system, the cervix is the passageway that connects the uterus and the vagina. Cervical cancer is the third most common cancer in women worldwide and is a leading cause of cancer deaths in women in developing countries (1).  The overall survival rate of cervical cancer in developed countries, however, is quite good. In Canada, the overall five-year survival rate of cervical cancer is 73%.  The sooner the cancer is treated, the better the chance of survival (2).

Benign Conditions and Precancerous Conditions

A malignant, or cancerous, tumour is one that can spread, or metastasize, to other parts of the body. Cells in the cervix may start to behave abnormally, however, to produce benign, or non-cancerous, tumours such as polyps, cysts, or fibroids. There are also some changes that cause conditions known as precancerous. This means that while the cells are not yet fully cancerous, there is a chance that they may develop into cancer if not treated. If untreated, it may take ten years or more to develop into cancer. Most women identified with precancerous conditions are successfully treated and do not ever develop cancer. Precancerous conditions are quite common and most often affect women in their 20s and 30s (3).

Risk Factors

Most cases of cervical cancer occur in women under 50 years of age. Women of African descent are more likely to develop cervical cancer than Caucasian women.  Cervical cancer affects those of lower socioeconomic status at a higher frequency than those at a higher socioeconomic status, mostly due to a lower rate of Pap testing in this group.

Human Pappillomavirus (HPV)

The most important risk factor for developing a precancerous condition of the cervix is infection with human papillomavirus (HPV). HPV is a common sexually transmitted disease with no noticeable symptoms. Women with early sexual activity or more sexual partners are at a higher risk of HPV infection, and subsequently, cervical cancer. An HPV infection may clear up on its own but may develop into a precancerous condition.

There is a vaccine to prevent HPV, which is increasingly becoming a part of the routine vaccination schedule for young men and women in developed countries. Other risk factors that increase the chance of HPV developing into pre-cancer are smoking, a weakened immune system, multiple pregnancies, or using oral contraceptives (4).

Symptoms

There are usually no signs or symptoms of precancerous conditions of the cervix. There may be some mild bleeding or spotting after sex. Since the symptoms are rare and subtle, routine screening is the most important tool to prevent and protect against cervical cancer.

Diagnosis and Staging

A Pap test, which should be completed every one to three years, is usually the first indication that the cells in the cervix are abnormal.  A Pap test is a procedure that removes a small number of cells from the surface of the cervix for examination under a microscope.  This test identifies any cells that look abnormal and may indicate that cancerous conditions are forming.  An abnormal Pap test indicates that further investigation and monitoring are required.  Doctors may then want to repeat the Pap test more frequently, every six months, to monitor if the cells are continuing to change.  An HPV test, usually done in conjunction with a Pap test can indicate the level of risk.

Doctors may perform a colposcopy, which is a procedure that uses a lighted magnifying instrument to examine the vulva, vagina, and cervix. Endocervical cutterage is a procedure that uses a special tool, called a curette, to remove cells from the cervix for more detailed examination.  They may require a complete blood count (CBC) or others tests to confirm a diagnosis. Once cancer is confirmed, doctors will use other tests to stage cancer, including biopsies, CT scans, MRI, intravenous pyelograms (IVP), PET scans, or others.

Doctors will use a number of techniques to stage cancer, determining how far it has progressed.  In Stage 0, the cancer is confined to the outer layer cells of the cervix. In Stage I, the cancer is moving deeper into the cervix but has not spread beyond it. In Stage II cancer has spread out of the cervix into the uterus but has not reached the walls of the pelvis or the lower part of the vagina. Stage II cervical cancer has not yet spread to the lymph nodes or other distal sites. In Stage III cancer has spread to the lower part of the vagina or the walls of the pelvis but has still not spread to the lymph nodes or other distal sites. In Stage IV the cancer has spread to other nearby or more distant organs such as the lungs, rectum, bladder, or liver (5).

Treatment

Most treatment for cervical cancer is a treatment for the precancerous conditions and is generally very successful. Mild changes to the cervix usually resolve themselves without any treatment, only close monitoring.  More severe changes are more likely to develop into cancer and are more likely to be treated.  Treatment for precancerous conditions may include loop electrosurgical excision procedure (LEEP), cryosurgery, laser surgery, or hysterectomy.

Treatment plans for cervical cancer are highly individualized and will take into account your age, your stage, your general health, whether you already have children or may want to have children, and your personal preferences.  There are several different surgical options including a cone biopsy, radical trachelectomy, total or radical hysterectomy, lymph node dissection, pelvic exenteration, or ovarian transposition. Other treatment options include radiation therapy, chemoradiation, chemotherapy, or targeted therapy (6).

Prognosis

A prognosis for cervical cancer is highly individualized, depending on several factors such as the women’s age and general health, and the stage of the cancer. Early detection and treatment is the key to successful cancer treatment.

The effectiveness of cervical cancer treatment has been linked to a woman’s pre-diagnosis iron level. Studies have shown that treatments are less effective in women with iron deficiency and may not be improved by blood transfusion designed to increase blood iron stores (3).

Types of Cervical Cancer

The most common type of cervical cancer starts in the flat, thin squamous cells that cover the lining of the outer surface of the cervix, and is called squamous cell carcinoma of the cervix. Cancer can also start in the glandular columnar cells that line the inner surface of the cervix, called adenocarcinoma of the cervix.  Other rarer forms of cervical cancer include adenosquamous carcinoma, glassy cell carcinoma, and mucoepidermoid carcinoma.

Squamous Cell Carcinoma

Squamous cell carcinoma, the most common type of cervical cancer, starts in the flat, scaly cells that cover the outer surface of the cervix.  This cancer develops in the transformational zone; the area where the columnar cells transform into the flat squamous cells. There are three types of squamous cell carcinoma (SCC):

Non-keratinizing SCC: the cells grow into separate masses

Keratinizing: the cells grow into irregularly shaped masses with keratin (a tough, fibrous protein) in the middle

Verrucous carcinoma: the cells develop into a tumour that looks like a cauliflower. This rare type of cancer tends to grow slowly and not metastasize.

Adenocarcinoma

This type of cervical cancer occurs more often in young women and accounts for 10-20% of all cervical cancers.  This type of cancer begins in the glandular cells of the inner cervix, which may become enlarged, or swollen.

Mucinous adenocarcinoma: the most common form of cervical adenocarcinoma

Endometrioid adenocarcinoma: this type of cancer is often mistaken for endometrial cancer, which develops in the inner lining of the uterus.

Clear cell carcinoma: occurs most often in the daughters of women who used a medication called diethylstilbestrol (DES) during their pregnancy. DES was prescribed to pregnant women between 1940 -1970 to prevent miscarriage and premature labour until studies demonstrated that it might lead to cancer. (7)

Other, more rare types of cervical cancer include: adenosquamous carcinoma, glassy cell carcinoma, mucoepidermoid carcinoma, adenoid cystic carcinoma, adenoid basal carcinoma, small cell neuroendocrine carcinoma, non–small cell neuroendocrine carcinoma, cervical sarcoma, and lymphoma of the cervix (3).

Prevention and Early Detection are the Key Determinants of Cervical Cancer

Cervical cancer is a dangerous, yet highly preventable type of cancer that affects young adult women. Most cervical cancers are caused by human papilloma virus and can now be prevented with the HPV vaccine. Although there are no early symptoms or warning signs, cervical cancer can be detected early during routine Pap testing and, if treated early, has a high survival rate.

 

Written by Lisa Borsellino, BSc

References

  1. Arbyn, M, et al. Worldwide burden of cervical cancer in 2008. Annals of Oncology. December 2011, Vol. 22, 12, pp. 2675–2686.
  2. Boardman, Cecelia H. Cervical Cancer. Medscape. [Online] 01 26, 2018. [Cited: 01 26, 2018.] https://emedicine.medscape.com/article/253513-overview?src=refgatesrc1.
  3. Canadian Cancer Society. What is cervical cancer? Canadian Cancer Society. [Online] 2018. [Cited: 01 26, 2018.] http://www.cancer.ca/en/cancer-information/cancer-type/cervical/cervical-cancer/?region=on.
  4. Mayo Clinic. Cervical cancer. Mayo Clinic. [Online] Aug 23, 2017. [Cited: 01 26, 2018.]
  5. America, Cancer Centre Treatment of. Cancer Centre Treatment of America. Cervical Cancer. [Online] 2017. [Cited: Jan 28, 2018.]
  6. Haie-Meder, C, Morice, P and Castiglione, M. Cervical cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up. Annals of Oncology. May 1, 2010, Vol. 21, 5, pp. 37-40.
  7. NIH National Cancer Institute. Diethylstilbestrol (DES) and Cancer. [Online] Oct 5, 2011. [Cited: Jan 25, 2018.] https://www.cancer.gov/about-cancer/causes-prevention/risk/hormones/des-fact-sheet#q1.
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