by Gauri Panzade and Shriprada Labde
T.Y.B.Sc Department of Biotechnology DES Fergusson College, Pune. For BTH3507
Blog Category: Cancer Biology
According to the estimates of 2018, it was observed that 96922 cases of cervical cancer occur annually in India and 60078 deaths have occurred because of it. Seems high right? Afterall, cervical cancer is the second most prevalent type of cancer after breast cancer in females. There are 453.02 million females in the age group 15 and above who are at a risk of developing this cancer. It is also the second frequent type of cancer in the age group 15-44. The real question that lies ahead is what do we know about cervical cancer? All the answers to 5Ws and an H (Who, what, when, where, why, how) related to cervical cancer will be discussed here.
Let’s start with the basic and the most important question, what is cervical cancer? Cervical cancer is a type of cancer that affects the cells lining the cervix. Cervix is the connection between uterus and vagina. The part of the cervix that opens into the uterus is called endocervix and it is lined by glandular cells. The part of the cervix that opens into vagina is called exocervix or ectocervix and it is lined by squamous cells. Transformation zone is the area where both squamous and glandular cells meet. Based on the type of cells affected, cervical cancer is of following types- 1) Squamous cell carcinomas- Most common type of cervical cancer arising from the squamous cells of ectocervix. This cancer begins from the transformation zone. 2) Adenocarcinomas- This type arises from glandular cells of endocervix. 3) Adenosquamous carcinomas- It is also called as mixed carcinomas. This type has features of both squamous cell carcinomas and adenocarcinomas. However, it is not very common.
What causes cervical cancer? Cervical cancer is mostly caused due to the preceding infection of human papillomavirus (HPV). This virus is
sexually transmitted and is very common in sexually active males and females. HPV infects cells in the transformation zone. Most HPV infections resolve on their own. Some types of HPV show persistent infections. E6 viral protein causes inhibition of apoptosis and E7 causes inhibition of cell cycle arrest of infected cells. This causes abnormal changes in the cervical cells(dysplasia) and it is called as cervical intraepithelial neoplasia (CIN). Over the time if HPV infection is not resolved then they turn the pre-cancerous cells into invasive cancer. HPV type 16 and 18 cause 70% of the cervical cancer and pre-cancerous cervical lesions. Based on the severity of abnormality, CIN is classified as - CIN1 (mild changes in cells), CIN2(moderate changes in cells), CIN3(severe changes in cells). CIN1 resolves on its own. CIN2 and CIN3 are pre-cancers and may become cancerous if not treated.
What are the symptoms of cervical cancer? Cervical cancer doesn’t develop quickly. One may not know what’s hiding in their closet or cervix in this case. Cervical cancer slowly and gradually creeps on you. That’s why the early stages don’t generally show any symptoms. However, the advanced stages show signs and symptoms like vaginal bleeding (post coital, between periods or post menopause), vaginal discharge with foul odour or pelvic pain and pain during intercourse.
Now, moving ahead to the next W i.e. ‘Who’. Who are at the risk of getting this cancer? Females having multiple sexual partners, being immune-compromised (having weak immune systems), or having other sexually transmitted diseases will increase the risk for HPV and in turn cervical cancer. Also, females who smoke, take birth pills for long time, take miscarriage prevention drugs are at risk.
Why should we do screening tests? As the phrase says ‘be cautious than sorry’. Screening tests are used for early detection of pre-cancerous cells. These cells can be treated and cervical cancer can be prevented. 1)HPV test- As HPV is the risk factor for development of cancer, it is important to be tested for high risk types of HPV. 2) Pap test (Papanicolaou test) – The cells of cervix are scraped by using a spatula or a brush and are then sent to laboratory for observation. It is checked whether the cells are normal or abnormal.
It is to be noted that screening tests are not diagnostic tests and further tests have to be done to diagnose pre-cancer and cervical cancer.
When should the screening be done? All females of age 21 and above should get Pap test done after every 3 years. HPV test is only for females who are above 30 years old. Women of age group 30-65 can take a Pap test alone after every 3 years, HPV test alone after every 5 years or a co-test (both Pap test and HPV test) after every 5 years.
How is cervical cancer diagnosed? Based on the results of screening tests, age, physical examination and medical history, further testing is carried out. Abnormal Pap test result is followed by colposcopy. A colposcope is a magnifying device used to examine a cervix clearly. If areas of abnormal cells are seen then biopsy (removal of a small piece of tissue for examination under microscope) is carried out. Biopsy gives definite diagnosis of pre-cancer or cancer. There are various types of cervical biopsies. Colposcopic biopsy- During colposcopy, a small section of tissue is cut using forceps and observed microscopically. Endocervical curettage- A curette is an instrument with hook/scoop like tip which is used to scrape the inner side of the endocervical canal. Cone biopsy- A cone shaped piece of tissue is removed from the cervix under general anesthesia. Cone biopsy can also be used as treatment for pre-cancer and very early stage of cancer. Loop electrosurgical procedure (LEEP)- A heated wire loop using electric current is used for removing a section of abnormal area of the cervix. It is used as both diagnosing test and treatment.
What are the stages?
● Stage 1 - Cervical carcinoma is confined to cervix
● Stage 2 - Carcinoma invades beyond cervix but not to pelvic wall or lower 1/3 of vagina
● Stage 3 - Carcinoma extends to pelvic wall and lower 1/3 of vagina
● Stage 4 – Carcinoma extends to bladder, rectum and metastasis occurs
How is the staging of cervical cancer done? CT-scan, PET-scan and MRI are used to measure tumor size, to see if metastasis is occurring or not, to see other regions where it has metastasized. Based on the results of scans, physical examination, biopsy and hysteroscopy (examination of uterus using hysteroscope), staging is done
The most important question is how can the cervical cancer be treated? Treatment includes surgery, chemotherapy, radiation or a combination of the three. Treatment is planned according to the stage and type of cancer, patient age, desire to have a baby.
● Surgery methods-1)Cryosurgery - Destroying cancer cells by freezing them with low temp device 2)Laser surgery - Using laser to destroy cells 3)Cone biopsy 4)LEEP 5)Laparoscopic surgery - Small incision is made and camera is inserted for observing during surgery 6)Open surgery - Large cut is made and tumor is removed surgically 7)Trachelectomy - Whole cervix is removed for complete cervical cancer removal 8) Hysterectomy - If the cancer has metastasized to uterus then whole uterus along with the cervix is removed.
● Chemotherapy – Medications are given to shrink the tumor or stop the cancer cells from dividing. It is done in combination with radiation. Chemotherapy causes side effects as healthy cells are also exposed to drugs.
● Radiation- High energy x-rays or other types of radiations are used to destroy the cancer cells.
Cervical cancer can be prevented by having a healthy and proper lifestyle. Reduce the risk factors like stop smoking. Two doses of HPV vaccine are recommended to the age group 11-12 years with the second dose being administered 6-12 months after the first dose. HPV is recommended to women until the age 26. Just by taking two doses, one not only gets prevention from HPV infection but also from cervical cancer that can develop due to HPV infection. Routine HPV and Pap tests save lives because there is early detection of cancer and its treatment. However, many women avoid getting screening done due to the stigma around it, shyness, less knowledge about cervical cancer, low financial status etc.
Thus, people should be made aware about the importance of screening, educated about the cervical cancer and routine screening should be inculcated because prevention is always better than cure! So, let's break away the stigma and talk about it.
References
Smith, Jennifer S., Lisa Lindsay, Brooke Hoots, Jessica Keys, Silvia Franceschi, Rachel Winer, and Gary M. Clifford. 2007. "Human Papillomavirus Type Distribution in Invasive Cervical Cancer and High-grade Cervical Lesions: A Meta-analysis Update." International Journal of Cancer 121.3 (2007): 621-32. Wiley Online Library. Web. https://onlinelibrary.wiley.com/doi/10.1002/ijc.22527
Schiffman, M., Castle, P.E., Jeronimo, J., Rodriguez, A.C. and Wacholder, S., 2007. Human papillomavirus and cervical cancer. The Lancet, 370(9590), pp.890-907. http://www.umanitoba.ca/faculties/health_sciences/medicine/units/medical_microbiology/courses/MicroPath97.705/PDF/10.13.pdf
Crosbie, E.J., Einstein, M.H., Franceschi, S. and Kitchener, H.C., 2013. Human papillomavirus and cervical cancer. The Lancet, 382(9895), pp.889-899. https://poliklinika-harni.hr/images/uploads/153/hpv-karcinom-cerviksa.pdf
HPV INFORMATION CENTRE, 2019, India Human Papillomavirus and Related Cancers, Fact Sheet 2018 (2019-06-17), www.hpvcentre.net/statistics/reports/IND_FS.pdf?t=1598869715563
“What Is Cervical Cancer?: Types of Cervical Cancer.” American Cancer Society, www.cancer.org/cancer/cervical-cancer/about/what-is-cervical-cancer.html
"What Should I Know About Cervical Cancer Screening?" Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 07 Aug. 2019. Web. 31 Aug. 2020. https://www.cdc.gov/cancer/cervical/basic_info/screening.html
Fayed, Lisa. "How Cervical Cancer Is Treated." Verywell Health. 17 July 2019. Web. 31 Aug. 2020. https://www.verywellhealth.com/cervical-cancer-treatments-582042.
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