Worldwide cervical cancer remains a scourge. It is the second commonest cancer affecting women. It is impossible to put a figure on the actual number of cases since accurate diagnosis and registration are neither available nor indeed possible in many countries. It is estimated, however, that at least 450,000 women are so afflicted annually. At least 9 out of 10 of these are women in the developing world. Women in the developed world are protected to a greater or lesser extent by screening programmes aimed at detecting pre-cancerous changes. These programmes are so effective that in some situations women are at risk of over-investigation, over-diagnosis and over-treatment in the massive and expensive effort which aims to prevent their developing cervical cancer let alone dying from the disease.

In 1925, Hans Hinselmann (1) devised the colposcope. In simple terms this amounted to a binocular instrument mounted on a stand which allowed a magnified and stereoscopic view of the cervix through a speculum. He was endeavouring to detect the earliest forms of cervical cancer. In 1943, Papanicoloau and Traut (2) described the appearances of cells scraped from the surface of cervices affected by disease where the apparent malignant changes in the cells were confined to the epithelium in so-called carcinoma in situ. Thus two quite distinct methods for potentially screening a population came into being. The former required considerable training and expertise and required the physical presence of the woman. Colposcopic screening spread from Germany through other parts of Europe including Spain and thence to South America. The latter demanded less expertise for harvesting the cells which could then be examined and re-examined in the laboratory in the absence of the woman herself. The English speaking world adopted this primary cytological approach and thus, for many years, colposcopic screening and cytological screening were seen to be in competition rather than complementary approaches to a common problem.

In the early 1960's, the oral contraceptive pill became widely available and screening was extended to a younger population. Squamous cervical cancer which accounted for at least 95% of all cervical malignancies had a peak incidence in women aged 45-55. Most women undergoing screening were at least 35 years old and, not surprisingly, most cases of carcinoma in situ thus found were in women over the age of 35. Commonly, such women had completed their families and the standard treatment for a carcinoma in situ by hysterectomy was not unacceptable to them. Some were subjected to what we would clearly recognise now as over-treatment namely radical surgery, pelvic lymphadenectomy or indeed pelvic irradiation. Some women, however, wished to retain their fertility and with the help of pioneering gynaecologists were able to do so by undergoing cone biopsy rather than hysterectomy. When cervical screening was extended to much younger women who, far from having completed their families, had in many cases not yet embarked upon starting one then hysterectomy became totally unacceptable. Indeed large cone biopsies, in some cases, led to an increase in operative delivery or even infertility through scarring and stenosis and in others miscarriage and premature delivery through cervical incompetence. Clearly, an increasingly conservative approach was called for if this could be adopted with safety. Thus the way was paved for the marriage of colposcopy and cytology.

Cervical cautery was commonplace 50 years ago. Gynaecologists were predominantly male and the appearances of the cervix in the young woman, especially in the postnatal period, offended the uninitiated. The red appearance of the central cervical area seen through thin, transparent columnar cells without the aid of a colposcope was commonly mistaken for ulceration and described as erosion. It was customary for such gynaecologists to destroy this area with electric cautery or diathermy. Occasionally, a young woman with cytological or colposcopic evidence of early cervical disease but wishing to retain her fertility, would see an enlightened gynaecological pioneer who would cauterise the cervix rather than carrying out cone biopsy. This was first described in 1945 but did not become fashionable until the early 1970's.

Women with a positive smear, i.e. one showing high-grade abnormality in keeping with the diagnosis of carcinoma in situ were increasingly referred for colposcopy. Diagnosis was confirmed by colposcopically directed punch biopsies and the cervical transformation zone, i.e. the area where columnar epithelium normally underwent metaplastic change to squamous epithelium, was cauterised, diathermied or electrocoagulated. These techniques, however, were predominantly carried out in operating theatres under general anaesthesia albeit the patients being dealt with as day cases. The alternative of freezing the cervix was understood to be less painful and could be carried out in the outpatient clinic without anaesthesia. Increasing availability of colposcopy and the establishment of national societies of like-minded individuals led to national co-operation and the establishment of an international federation for colposcopy and cervical pathology, which led to widespread interest and increased expertise in colposcopic practice. The development of laser technology in the mid-1970's led to increasing use of this modality which was seen to be much more precise and thus more sophisticated than electrocoagulation diathermy and cryosurgery.

Within five years concern was being expressed that destruction of the cervical lesions by carbon dioxide laser could be too precise. Treatment confined to the visible lesion resulted in a higher failure rate than the "low tech" forms of treatment. Extension of the laser to destroy the whole of the transformation zone including the lower endocervix resulted in cure rates as good as electrocoagulation diathermy but became laborious in the way that eating peas with a cocktail stick can be compared to eating them with a fork.

In the early 1980's, it was generally appreciated that, in the hands of experts, various extremes of heat or cold could effectively destroy precancerous cervical lesions thereby preventing the development of cervical cancer. Large numbers of women were identified with abnormal smears. Large numbers were referred for colposcopy, and large numbers had their cervical transformation zones destroyed. Enthusiasts championed their chosen modality. Studies confirmed that each were equally effective and their selection was based on other factors. With the increase in numbers reports began to appear of cervical cancer developing despite conservative treatment. A disproportionate number of these were adenocarcinomas and adenocarcinoma in situ was described as a new, albeit rare, clinical entity. Concern grew that small numbers of pre-existing cervical cancers and co-existing glandular lesions were being missed and undertreated and the pendulum began to swing. Proponents of laser announced that their instruments could excise the transformation zone just as easily as destroying it thus providing more tissue for histological examination and improved diagnosis. Laser cones became the "in thing".

In the 1960's, cone biopsies were often known as "cold-knife conizations" to distinguish them from "hot-loop conizations". The latter were used to remove the transformation zone in small pieces largely unsuitable for histological examination in women who had benign cervical "erosion" and troublesome symptoms. Cartier (3) had modified the electric current and demonstrated that the loop technique could yield pieces of tissue suitable for histological examination. Prendiville at al. (4) took this one step further. Refining the technology for combining cutting and coagulating current and using a series of larger loops, he was able to devise a technique of removing the transformation zone in fewer pieces allowing better orientation of the tissue for histological diagnosis and the assessment of surgical margins. His large loop excision of the transformation zone (LLETZ) or loop electrosurgical excision procedure (LEEP) as the Americans prefer to call it has been widely adopted and in the 1990's became the most common method for treating cervical precancer. Those few individuals with unsuspected microinvasive cancer of the cervix or adenocarcinoma in situ are more likely to have their lesion detected with this method. At the other end of the scale, however, large numbers of women with small, early or transient lesions risk being over-treated if LLETZ is used injudiciously. A single LLETZ is unlikely to threaten fertility or reproductive performance but if carried out in the first instance in a young immature cervix and then repeated for some low-grade persistent cytological abnormality then the old anxieties regarding knife cone biopsy may re-emerge.

In developed countries where cervical screening has now become a highly organised computerised programme of call and recall acceptable to almost everyone in the eligible age groups, the incidence of and mortality from cervical cancer are continuing to fall. Excision of the transformation zone is, once more, more common than destruction although the latter still has its advocates when the cervical lesion is visible colposcopically in its entirety, there is no suspicion of invasion, microinvasion or a high-grade glandular lesion on clinical, cytological or colposcopical grounds, and the cervix has not been previously treated with a destructive method.

For the foreseeable future, colposcopy will continue to be used in the routine examination of women as an aid to the diagnosis of infection as well as neoplasia in many parts of the world. It will continue to be used as a convenient means of examining other areas of the body. Developing technology allowing human papillomavirus detection and ascertainment of the physical as opposed to the chemical properties of cervical epithelium may supplement and indeed at some point supplant cervical cytology. Colposcopy itself may evolve with the development of video colposcopy especially for data capture and for training purposes but the colposcopy in whatever form will remain at the crux of cervical treatment in the prevention of cervical cancer.

IAN D. DUNCAN