Cervical Cancer Diagnosis
Here we discuss investigations required to confirm the diagnosis of cervical cancer and stage the disease.
George Papanicolaou in 1920 discovered that tumor cells could be found in vaginal fluid of women with cervical cancer. There has been 75% reduction in the incidence and a 70% reduction in the mortality from invasive cervical cancer due to the Pap test. IARC data suggests that even screening women just once in their lives, at age 35 could reduce cervical cancer incidence by 40% and mortality by 26%.
Procedure of PAP Smear
- The patient should not be actively menstruating. (8-12th day )
- It is preferable that the patients refrain from sexual activity or use of vaginal medications or spermicides for the 48 hours prior to the test.
- Appropriately sized bivalve speculum should be used. Instead of lubricant jelly, water should be used for easier passage of speculum.
- If mucus or small amounts of blood are on the cervix, gently remove with a large cotton swab (to avoid removing cells from the transformation zone).
- Scrape cervix with the Ayre’s spatula by inserting the larger irregularly shaped side of the spatula into the endocervix and turning 360 degrees, making sure to cover the entire transformation zone.
- Spread the cells from the spatula onto a numbered slide, evenly, avoiding clumping. Immediately fix the smear in a coplin jar containing 95% alcohol.
Liquid Based Cytology
It is a technique which provides a uniform thin layer of cells for examination in smear without any debris / cell contamination. The cervix brush is used to collect the sample. Central bristles inserted into cervical canal and lateral bristles fully bend against Ectocervix and then rotated for 5 to 9 times. No smear needs to be prepared and the entire sample collected by the brush is transported to the laboratory in the fixative vial after proper labeling.
Visual Inspection Methods
Their advantages are that they are simple, safe and well accepted, require very low infrastructure, can be performed by a wide range of personnel with a short training (1-3 weeks) and provide immediate results. But these also have some disadvantages like lesions may not be readily visible in women over 50 years of age as squamocolumnar junction recedes towards the endocervix. Moreover, underlying infections may increase inflammation and render the inspection difficult. Also, the specificiity of these tests may be lower.
Visual inspection using acetic acid (VIA)
In this test, clinical inspection of cervix is done using only a speculum and light source. Patient is positioned in a modified lithotomy position on a couch and a sterile vaginal speculum is gently introduced. 5% acetic acid is applied using a cotton swab soaked in acetic acid and cervix carefully look at to see whether any white lesions appear, particularly in the transformation zone close to the squamocolumnar junction, or dense, non-removable acetowhite areas in the columnar epithelium. The results one minute after application of acetic acid should be reported. Acetic acid causes reversible coagulation of intracellular proteins called as ‘Acetowhitening’.
Visual inspection using Lugol’s Iodine (VILI)
Lugol’s Iodine stains glycogen stored in the cervical epithelial cells. The mature squamous epithelium is stained black or dark brown, whereas, the cancerous epithelium stains saffron yellow.
HPV DNA Testing
Persistent infection with an oncogenic type of HPV is the necessary cause of developing cervical carcinoma. HPV DNA is found in 99.8% of all cervical cancer cases. The table below compares the sensitivity and specificity of Pap test and HPV DNA testing. As we can clearly see, the sensitivity of HPV DNA test is much better as compared to that of Pap test. Specificity of this test is lower than conventional pap. But when used together with Pap test, sensitivity of both tests used together is 100%, and the specificity is 92.5%. The risk of CIN 3 or cancer is approximately 1% among women with a negative test for HPV.
|Pap||55.4 %||96.8 %|
|HPV DNA testing||94.6 %||94.1 %|
Colposcopy is a diagnostic technique which uses a colposcope – a device equipped with magnifying lenses, a light source, and some special instruments for biopsy or surgery. This device enable doctors to closely examine the cervix surface to determine the presence of abnormal cells. Cervical surface is first treated with a 3% acetic acid solution that reacts with the HPV proteins, dehydrate the dysplastic cells (if any), and allow easy identification of any abnormal cells in the cervix. Some other reagents like Lugol iodine may also be used to distinguish between low and high-grade lesions. Doctor can also collect biopsy samples with the help of a biopsy forceps if an abnormal area is observed during the procedure.
Biopsy sample(s) from the cervix is generally collected in case an abnormal area(s) is observed during the colposcopy procedure. Endocervical curettage/scraping: This technique is used when the entire transformation zone could not be visualized via colposcope. A biopsy sample from the endocervical canal is obtained with the help of a curette scraping or sleeved endocervical brush. The biopsy sample is then tested in a laboratory for the presence of any abnormal/cancerous cells. Cone biopsy: This is a type of excisional biopsy also known as conization as a cone-shaped biopsy sample is removed from the affected area (mostly from the transformation zone) in the cervix. This technique can also be used as a treatment option for certain very early-stage cervical cancers that are limited to superficial cervical layer. This technique is employed for the diagnosis of cervical cancer, when:
- abnormal area extends up to the endocervical canal;
- high-grade cancerous lesion is suspected; or
- invasive carcinoma or adenocarcinoma in situ is suspected.
Following are procedures generally employed for cone biopsy:
Loop Electrosurgical Excision Procedure (LEEP): In this procedure, a thin wire loop that can be heated with electricity is used to obtain cone biopsy from the transformation zone.
Cold Knife technique: In this procedure, a surgical scalpel or a laser is used to excise the cervix tissue.
These help in detemining the extent of locoregional and distant spread of the disease and determine the stage.
- Computed tomography (CT) scan
- Positron emission tomography (PET) scan
- Magnetic resonance imaging (MRI) scan
- Intravenous pyelogram (IVP)
- Chest X-ray