Early diagnosis method of cervical cancer

No matter which woman has cervical cancer, her family and friends do not want to see it. If female friends must consider their own health, they must do a good job of prevention and regular examinations in advance. If they are found, the chance of cure will be very high. Because the early symptoms of cervical cancer are not obvious, it is usually discovered in the middle and late stages, and it is more difficult to treat. It is best to detect and treat it early. So what are the diagnostic methods for early cervical cancer?

There are several main ways to diagnose cervical cancer:

(I) Visual observation

Visual observation is to apply a 5% glacial acetic acid solution to the cervix and then directly observe the reaction of the cervical epithelium to acetic acid. The lesion area turns white. The advantages of this method are easy training, low cost, rapid feasibility, and suitable for screening a large population. The disadvantages are that the sensitivity and specificity are relatively low, about 50%, and most of the screened cases are invasive cancer and early cancer rather than precancerous lesions. Due to the high false positive and false negative problems of visual observation, it should be used in combination with cytology when conditions permit. Compared with cytology, the reliability of visual observation is relatively low, but given its good economy and feasibility, it can be used as a method for coarse screening of cervical cancer in areas where cytology technology is limited.

Experimental studies of this method have begun in some developing countries, and its value in cervical cancer screening needs further evaluation.

(ii) Colposcopy

Colposcope is an endoscope. Its principle is to directly observe the lesions of the cervix and lower genital tract epithelium with a binocular stereo magnifier under a strong light source. It is one of the important auxiliary methods for early diagnosis of cervical cancer and precancerous lesions. When clinical suspicion or abnormal cytology is found, colposcopy is often recommended. The combination of colposcopy and cytology can reduce the occurrence of false negatives. Literature reports that the sensitivity of colposcopy diagnosis and the consistency rate with histology are better than traditional cytology. A randomized double-blind population screening study showed that the sensitivity and specificity of colposcopy were lower than those of thin-layer liquid-based cytology, with significant statistical differences.

The accuracy of colposcopy is usually affected by the experience and technical level of the examiner and the examiner. Cervical cancer often occurs in the transition zone of the cervical epithelium. Around the time of menopause, about 12% of the squamous-columnar junction of the cervical epithelium moves up to the endocervical canal. However, it is difficult to observe the lesions in the endocervical canal with a colposcope, which often results in false negatives. Endocervical curettage or cone biopsy is performed to assist in diagnosis when necessary. Although colposcopy is widely used as a screening method in Europe, most developed countries believe that it has low specificity and is not suitable for screening. In developing countries, it is not widely used as a screening method because of its high cost and the need for specialized technicians with certain experience. The electronic colposcope system (Jinkewei, Shenzhen) developed by my country has played a major role in cervical cancer screening and follow-up observation of precancerous lesions due to its clear images, realistic colors, convenient image storage and access, and simple operation.

(III) Cervical photography

Cervical photography is to use a special camera to magnify the cervix and take a picture, and then project the picture at a short distance to magnify it 16 times for reading. Generally, people who have not received colposcopy training can operate this technology, but the reading of the film must be done by an experienced physician, and the photos can be preserved permanently. Currently, only one company (National Testing Labs) has the patent for this method, and all cervical films are read by this company. Comparative studies of the two screening methods of Pap smear and cervical radiography have shown that for those with high-grade lesions, the detection rate of Pap smear is higher than that of cervical radiography, and for those with low-grade lesions, the detection rate of cervical radiography is higher than that of Pap smear. Some other studies on cervical radiography have also reached the same conclusion: the characteristics of high sensitivity and low specificity of cervical radiography are not suitable for use alone in cervical cancer screening, and there is no sufficient cost-effectiveness, so it only plays an auxiliary role in screening. This method is rarely used in cervical cancer screening at home and abroad.

(IV) Fluorescence microscopy

Fluorescence microscopy is a diagnostic technique developed after cervical photography. Using light of a specific wavelength to shine on the cervix, the intensity of fluorescence emitted by the tissue depends on changes in cell chemistry and tissue structure. Precancerous tissue has different cell structures compared with normal tissue, such as increased blood vessels and keratin changes, so as to distinguish cervical neoplastic lesions (CIN) from abnormal injuries. The advantages of this method are that it is non-invasive, painless, simple and fast, and the diagnostic rules are stored in computer software. It has been reported that in cases with abnormal cytology, fluorescence microscopy was used to distinguish CIN from non-neoplastic lesions, with a sensitivity and specificity of 87% and 73%, respectively. A recent study in my country used fluorescence microscopy to screen cervical cancer and precancerous lesions in women in high-incidence areas, with a sensitivity of 94% and a specificity of only 9%. The reason is that the former is diagnosed on the basis of cytological results and has a certain tendency, while the latter is to screen cases in the population, with a randomized double-blind design and strong objectivity, indicating that fluorescence microscopy cannot be used for population screening at present and needs further development.