Population Screening for Cervical Cancer - Essay Example

Running head: POPULATION SCREENING FOR CERVICAL CANCER Population Screening for Cervical Cancer Subject Name of the Professor/Instructor March 20, 2006. ABSTRACT The paper is first introduced with cytological description of the cervix and uteral area followed by pictorial description of malignant cells. Then the different smear techniques are discussed along with their advantages and disadvantages followed finally by the rationale for screening among different age groups of women. Population Screening For Cervical Cancer According to the National Cancer Institute two different types of cells form the surface lining of cervix: 1. Tall, glandular cells or columnar cells make up the mucus and guard the entrance of uterus. 2. Squamous epithelial cells or squamous cells which are thin, flat and arranged in layers. Figure 1 Figure 2 Fig: 1 Pictorial depiction of Endocervical canal and Cervix (Source: National Cancer Institute). Fig: 2 Different types of cells of the cervix (Source: National Cancer Institute). According to the American Cancer Society, majority of Cervical Cancers start at the junction of endocervix and ectocervix. Cervical precancers and cervical cancers are classified based on their appearance under the microscope: 1. Squamous Cell Carcinoma - comprises of about 80% to 90% of cervical cancers, wherein the thin, flat squamous cells cover the surface of endocervix. This type of cancer generally begins at the junction of ectocervix and endocervix. 2. Adenocarcinoma - comprises of 10% to 20% of the cervical cancers, wherein the adenocarcinoma develops from the mucus generating gland cells of endocervix. 3. Adenosquamous Carcinoma - rarely do cancers have the features of both the adenocarcinoma and squamous cell carcinoma, these are also called mixed carcinomas (2006). Figure 3: Normal cervical cells Normal and precancerous mix Precancerous cervical cells (Source: National Cancer Institute). According to the National Cancer Institute, cell changes may occur due to human papillomavirus (HPV) infections, which is a very common virus. About 15 types of HPV cause cervical cancer. HPV is considered as the most common risk factor for cervical cancer and the virus can be detected with the help of a HPV test. According to the American Cancer Society all women should undergo screening (Pap smear test) every three years after beginning vaginal intercourse but not later than 21 years. Regular Pap test should be done annually once or newer liquid-based Pap test done every two years. Women above 30 years of age may get tested every three years by either of the methods and HPV DNA test. Women above the age of 70 years with 3 or more normal Pap tests in a row and no abnormal results in the last 10 years and also women who have undergone hysterectomy (removal of uterus and cervix) unless the surgery was done as treatment for cervical cancer may choose to stop. But women with a history of cervical cancer, or diethylstilbestrol (DES) exposure before birth, or HIV infection, or a weakened immune system due to organ transplant, or chemotherapy, or chronic steroid use must get tested yearly. Although Pap test is the best screening method, it is not a perfect method; since accurate analysis of thousands of cells under a microscope is humanly impossible even in the best of laboratories. Mucus and cell samples are collected with the help of a spatula by scrapping the ectocervix and another sample is collected by using a cotton-tipped swab or a brush from endocervix. The samples are then smeared on to a slide and examined under a microscope, but there are some limitations to this method. First the cells may be piled up due to which the cells underneath may not be clearly visible, second the cells may dry up and appear distorted if not properly treated with alcohol, third vaginal or cervical infections may result in inflammatory (pus) cells, increased mucus, yeast cells, or bacteria hiding the cervical cells. In the newer liquid based Pap test the sample is placed in a preservative solution and then spread on to a slide. The liquid based Pap test removes mucus, bacteria, yeast and pus cells in the sample and spreads the cells evenly on the slide, it also prevents drying up of the cells, thus avoiding a distorted view of the cells. US Food and Drug Administration (FDA) have approved the computerised AutoPap instruments that can spot abnormal cells in Pap tests. Computerised instruments locate most of the abnormal cells such as Atypical Squamous Cells (ASCs) in early stages itself. This type of automated testing method is more expensive than the conventional Pap smear test or Liquid based Pap test. The system adopted to report the results of Pap smear test is called The Bethesda System (TBS). The categorisation is as follows: Negative for intraepithelial lesion or malignancy - This means that no signs of malignancy or precancerous changes or other significant abnormalities were detected. Epithelial cell abnormalities - The abnormalities of epithelial cells depict abnormality of cells of the lining layer of the cervix, thus meaning that the changes may be due to a cancerous or precancerous condition. This category is further divided into several groups of squamous and glandular cells. The epithelial cell abnormalities for squamous cells are called: Atypical squamous cells (ASCs); these are further divided into ASC-US and ASC-H Low-grade squamous intraepithelial lesions (SILs) High-grade SILs Squamous cell carcinoma. Other malignant neoplasms - Most uncommon forms of cancer such as malignant melanoma, sarcomas and lymphoma belong to this category. Women having abnormal cervical cytology results are advised to undergo other tests such as colposcopy, biopsy and sometimes endocervical scraping (2006). According to Saslow et al, about 93 to 100 percent of squamous cell carcinoma of cervix contain DNA from the high risk group of HPV that are transmitted during sexual activity. Contrary to expectations it is found that the Pap test sensitivity for cervical intraepithelial neoplasia is between 70% to 80%. The limitations of test sensitivity are due to small size of a lesion, inaccessible location of the lesion, possibility of the lesion not being sampled, presence of few abnormal cells and presence of inflammation and blood leading to prevention of clear view (2002). According to Saslow et al., cervical cytology screening in adolescents may not yield appreciable results within first three years immediately after vaginal intercourse since the natural history of HPV infection, low - and high - grade cervical lesions suggest that the risk of missing an important cervical lesion until three to five years after initial exposure to HPV is least. "However, the concern is that screening before the three-year-period may result in an overdiagnosis of cervical lesions that will regress spontaneously, leading to inappropriate intervention, which may result in more harm than good." Since the risk of HPV transmission is low for sexual activities other than vaginal intercourse, it was selected as point for starting cervical cytology screening. On the other hand women over the age of 70 and not screened previously, those having a history of cervical cancer, in utero exposure to diethylstilbestrol (DES) and those who are immunocompromised including (HIV+) must undergo cervical screening. According to a general consensus cervical cancer is confined to unscreened and underscreened. There are evidences of very low risk among women aged above 50 years. But "since screening the unscreened has been shown to affect mortality rates, there is rationale to screen the elderly unscreened population." Further there are evidences to show that screening is associated with anxiety and discomfort during cytology sampling of some older women and may lead to higher health costs due to false-positive cytology results. In case of women who have undergone hysterectomy for cervical intraepithelial lesions and subtotal hysterectomy retaining the cervix must undergo cervical screening. Follow up cytology is recommended for every four to six months in women with Cervical Intraepithelial Neoplasia (CIN2/3) for whom hysterectomy was a recommended. Screening intervals are applicable to only those women who have been screened previously and have received a normal result. However the most appropriate screening interval is age dependant, women exposed to in utero DES must be screened annually (2002). According to Janicek et al., CT scan has become popular in management of cervical cancer, but CT scans are unreliable in detecting a subclinical parametrial disease and nodal metastasis less than 2 cm in diameter (2002). In conclusion patient's psychological thinking also may be borne in mind, whether a result is positive or negative, the irreparable damage done while the cytological samples are being collected and the result is due are difficult to measure. Cited References National Cancer Institute, Understanding Cervical Changes: A Health Guide for Women, Retrieved on March 21, 2006. American Cancer Society, Cancer Reference Information, What is cervical cancer Retrieved on March 21, 2006. American Cancer Society, Cancer Reference Information, Detailed Guide: Cervical Cancer.Can Cervical Cancer Be Prevented Retrieved on March 21, 2006. Debbie Saslow, Carolyn D. Runowicz, Diane Solomon, Anna-Barbara Moscicki, Robert A.Smith, Harmon J. Eyre and Carmel Cohen. American Cancer Society Guideline for the Early Detection of Cervical Neoplasia and Cancer, CA A Cancer Journal for Clinicians (2002). Mike F. Janicek and Hervy E. Averette. Cervical Cancer: Prevention, Diagnosis, and Therapeutics. CA A Cancer Journal for Clinicians (2001) Read More