© Borgis - Postępy Nauk Medycznych 7/2013, s. 492-495
*Aneta Słabuszewska-Jóźwiak, Grzegorz Jakiel
Profilaktyka cytologiczna raka szyjki macicy
The role of cervical smear in cervical cancer diagnosing
I Department of Gynaecology and Obstetrics, Postgraduate Medical Education Centre, Warszawa
Head of Department: prof. Grzegorz Jakiel, MD, PhD
Streszczenie
Rak szyjki macicy jest drugim pod względem częstości nowotworem złośliwym u kobiet na świecie. Zakażenie wirusem brodawczaka ludzkiego HPV stanowi najistotniejszy czynnik zachorowania na raka szyjki macicy. Przetrwałe zakażenie wywołane wirusem brodawczaka ludzkiego typu 16 i 18 przyczynia się do powstania ponad 90% płaskonabłonkowych i 75% gruczołowych raków szyjki macicy. Obecnie szacuje się, że HPV typu 16 i 18 jest najbardziej rozpowszechnionym wirusem przenoszonym drogą płciową. Szczepionka przeciwko wirusowi brodawczaka ludzkiego nie chroni przed wszystkimi onkogennymi jego typami, dlatego niezbędne jest kontynuowanie badań przesiewowych. W poniższym artykule przedstawiamy rolę badania cytologicznego w diagnostyce zmian przedrakowych i raka szyjki macicy. Według światowych rekomendacji populacyjny skrining zmian szyjki macicy powinien odbywać się w oparciu o cytologię wykonywaną co 3 lata u kobiet w wieku 21-59 lat. Badanie to może być uzupełnione, ale nie może zostać zastąpione przez test molekularny DNA HPV. Jednak najskuteczniejszą metodą unikania czynników rozwoju raka szyjki macicy jest edukacja zdrowotna informująca o czynnikach zwiększonego ryzyka zachorowania i kształtująca zachowania prozdrowotne.
Summary
Cervical cancer is the second most common malignant cancer in females worldwide. It is well-established that Human Papillomavirus (HPV) infections play a critical role in the development of cervical cancer. However, a large number of women infected with oncogenic HPV types will never develop cervical cancer. About 90% of adenocarcinoma and 75% squamous cervical cancers are causally related to persistent cervical infections by oncogenic human papillomavirus genotypes 16, 18. It is estimated that oncogenic papillomavirus genotypes 16 and 18 is the most frequent sexually transmitted virus. The HPV vaccination does not protect patients from all oncogenic HPV types, so it is essential to continue cytological screening. In this review article we describe the role of cervical smear in precancerous lesion and cervical cancer diagnosing. According to the recommendation the population-screening of cervical lesions should be performed every three years for women at age 21-59 years. This test can be completed but it can be replaced by a molecular test DNA HPV. However, the most effective way to avoid the cervical cancer is health education about the indicating factors.
Cervical cancer is the second most common malignant cancer in females worldwide. More than 470 000 new cases and 230 000 deceases are diagnosed every year. The average age of women in whom cervical cancer develops fluctuates between 45 and 50. An infection with Human Papillomavirus (HPV) constitutes the most essential factor of cervical cancer incidence. In 2008 the Nobel Prize Committee recognised the discovery of HPV in the process of cervical cancer carcinogenesis as the most important happening in the field of physiology and medicine. The main oncogenic type of the virus is HPV genotype 16, the second being genotype 18. HPV is transmitted mostly sexually, but also vertically and through a direct contact with an infected person. Serological typing of the virus allowed to differentiate non-oncogenic genotypes (HPV 6, 11, 40, 42, 43, 44, 54, 61), which cause condylomata acuminata on genital organs, and oncogenic genotypes (HPV 16, 18, 31, 33, 35, 39, 45, 51, 52, 56, 58) connected with a high risk of pre-neoplasm and neoplasm lesions of genital organs and anus. In women under 25 most infections with HPV regress spontaneously within 12 to 18 months. An infection lasting longer than 24 months is the main factor predisposing to the development of cervical cancer.
Cervical cancer prevention involves initial and secondary prophylaxis:
– initial prophylaxis – preventive vaccines, avoiding HPV infection,
– secondary prophylaxis – cytological screening, HPV testing or a combination of both techniques.
According to the WHO definition a screening test is a test, which conducted on healthy people allows for an early detection and treatment of a disease, the result of whose is decreased mortality in a population. A screening test does not diagnose a disease but only indicates its presence.
The key aim of population screening tests is to detect direct harbinger cancer lesions – that is cervical intraepithelial neoplasia (CIN) lesions or cancer. Detecting cervical pathology is possible due to the use of numerous standard and non-standard methods. The most common standard diagnostic methods are: conventional cytological smear, liquid based cytology (LBC), immunocytodiagnostics and colposcopy.
Cytological examination consists in collecting cervical specimens from the vaginal portion of the cervix and the endocervical canal with the use of a cytobrush on a microscope slide, and then fixing cells with a cytofix preparation. During the oncological assessment of smears a five-level Papanicolau classification (tab. 1) and the Bethesda system are used (tab. 2).
Table 1. The classification of cytological smears s according to Papanicolau.
| Cytological result | Cytological image |
| I° | Present correct cells of stratum superficiale
and intermedium, single leukocytes |
| II° | Present correct cells of stratum superficiale
and intermedium, existing glandular cells, metaplastic, existing bacterial flora, leukocytes, histiocytes |
| III° | Present dysplastic cells |
| IV° | Present dysplastic cells and single neoplasm cells |
| V° | Numerous neoplasm cells, leukocytes and erythrocytes |
Table 2. The assessment classification of cytological smears according to the Bethesda system. Brak odwołania do tabeli w tekście.
| Cytological diagnosis according to TBS | Cytological image |
| ASC-US | Atypical squamous cell undetermined significance |
| ASC-H | Atypical squamous cell cannot excluded HSIL |
| LSIL | Low-grade squamous intraepithelial lesion |
| HSIL | High-grade squamous intraepithelial lesion |
| AGC | Atypical glandular cells |
The classification by Papanicolau has played an invaluable role in the detection of pre-neoplasm states and cervical cancer. Nevertheless, it is currently being superseded by the Bethesda system (TBC), as the classification did not take into consideration the present knowledge about the carcinogenesis process in the area of cervix. The Bethesda system accounts for information about the quality of the specimen. It conditionally allows a smear for cytological assessment (it describes the presence or the lack of cells of the endocervical canal, the presence of inflammatory cells, the presence of erythrocytes) or disqualifies a smear from the assessment due to an incorrect technical procedure, too few cells in the specimen or an unreadable image because of numerous inflammatory cells, erythrocytes. Moreover, in case of an anomaly in the smear a cytologist uses a similar terminology to the one applied in histopathological diagnoses. According to the cytological classification which is in line with the Bethesda system and its modification from 2001 abnormalities of squamous cells which correspond to pre-cancer states were divided as follows:
1) ASC – atypical squamous cell:
a) ASC-US – undetermined significance,
b) ASC-H – cannot excluded HSIL,
2) LSIL – low-grade squamous intraepithelial lesion,
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