The story of an incomplete triumph
Until the mid 20th century, many women died unavoidably from cervical cancer, a fatal disease in the face of which medicine was helpless. Discovered through vaginal bleeding, it affected mainly - as still today - low-income women, often multiparous (multiple pregnancies), whose sex life started when they were very young - around 14 years - the age at which they often married. Sexually-transmitted diseases such as syphilis and gonorrhoea were frequent at that time, and nothing was known about papillomavirus transmission. The cancer became apparent around the age of 40 years and women died at about 45, leaving a large number of orphans.
It was a Greek pathologist, Papanicolaou, who, in 1945-1950, had the idea of taking a smear of cells from the surface of the cervix in women who had suffered bleeding and then died of cervical cancer. He then took the same samples of cells from women without symptoms. He was thus able to observe that, before developing a cancer, the cervical cells showed dormant and benign, but nonetheless pre-cancerous, abnormalities. And so it proved possible to diagnose and recognise them thanks to this sample, but only if carried out on all women. The idea of screening based on the cervical smear was born.
Yet it was not until the 1960s that the usefulness of the smear, the sole means of prevention at the time, really became apparent: not only did the abnormalities of certain cells denote a pre-cancerous state, but above all “extirpation” - removal of the abnormal “cone” area - allowed the disease to be prevented.
Then in 1976, Meisels and Fortin described a particular cell in the smear, the koilocyte, which looked strangely like the cells of genital warts, which were symptomatic of the presence of papillomavirus: these particular changes in the smear therefore probably came from this virus. So they hypothesised that the koilocyte, a cell visible on the smear indicating papillomavirus infection and reflecting the abnormalities of the cervix, was of viral origin. The hypothesis was confirmed when the human papillomavirus was identified in the abnormal cervical cells when examined under an electron microscope, followed by biological methods which confirmed the presence of these viruses in the nuclei of the abnormal cells. They had just proved that the altered cells detected in the smear were indeed the expression, or consequence, of the infection.
Having demonstrated this, women were then invited to consult their doctors regularly for a smear. But it soon became apparent that, to be effective and beneficial, screening had to include all healthy women of all social categories throughout their lives. To this end, some countries, as we have seen, put in place proper, organised screening programmes where women were invited by name to consult a physician every three years, free of charge. This is the case in Finland and other Scandinavian countries which have gradually integrated prevention into women´s lives. England was subsequently to copy this model. Thus, with this system of invitation, it was possible to monitor a large part of the female population and register drastic falls in the disease - over 70% in some countries.
In other countries, such as France, screening was left up to the individual, and occurred in a more spontaneous or voluntary manner.
However, with the advent of the contraceptive pill in the 1960s through to the “Women´s Liberation” campaign in the 1970s, screening has become common practice. This was because, while contraception offered women greater sexual freedom, it also exposed them to all forms of sexually-transmitted infections (STIs) - chlamydia, herpes and, of course, papillomavirus. So contraceptive check-ups and STM risks forced them to consult their doctors. There remained the problem of women who were not taking the Pill or who, after the menopause, no longer felt they had any reason to see their doctor (a situation which improved slightly after 1990, thanks to the increased popularity of a hormone replacement treatment for menopausal women, though this situation has worsened again over the past three years due to health scares).
For many women, therefore, the smear is a necessary examination only if they have a sex life, as it is often linked to the prescription of a contraceptive. I will return to the danger of this concept, since, even if women are no longer sexually active, this does not mean that they can forget about gynaecological monitoring. It is important to realise that cervical cancer manifests, on average, 15 to 20 years after sexual exposure to the papillomavirus, and during this period the virus lies dormant and has no reason to remind anyone of its existence.
To sum up, the benefit of screening in countries where this is left to the individual initiative is mitigated. While the fall in the frequency of cancer in France since the 1970s is certainly very significant, going from 10,000 to less than 4,000 in the year 2000, thanks primarily to the number of specialists and reimbursement by social security, the figures have stagnated for the past eight years and are still too high for a cancer thought to be avoidable. Inequalities in access to healthcare, lack of information or even ignorance in certain at-risk populations, the absence of a strict schedule, allowing some people to abuse the system with all the economic consequences this entails, and yet allowing others not to have any checks: this gives some idea of the limits of a system such as this.
What is a smear?
In the minds of women, the regular, often annual, visit you make to the gynaecologist is very often associated with the smear. And you dread this unpleasant or painful examination. The announcement of the result concerns you or is a source of anxiety, since it is not immediate but arrives two to three weeks later: the time it takes to send the sample to a laboratory, interpret it and pass the results on to the doctor.
The smear, still called the Papanicolaou test, is a test which screens for abnormalities in the cervical cells. Its objective is to detect early and benign changes in cells which could possibly constitute a cancer risk. It is important to understand that the smear needs to be performed on “healthy” women before any symptoms appear. Even if you feel in good health, even if you are no longer sexually active, the smear is still an essential examination regardless of all these considerations.
The smear is generally carried out by a doctor, usually a gynaecologist but sometimes by a general practitioner, or a trained nurse.
For the smear itself, the patient lies on an examination couch, a speculum is used to part the vaginal walls and gain access to the raised, convex area at the back of the vagina we described earlier: the cervix. With good lighting, the physician can see the cervix from where the sample is to be taken.
I recommend that my patients avoid having a smear at the time around their period or if they have any break-through bleeding, infections or abnormal discharges. I recommend that vaginal douches not be carried out, nor creams, pessaries, gels or tampons used for two days before the smear, as any of these could affect the cells or reduce the number in the sample. Nor should the patient have sex for the two days prior to the smear.
In some cases, in particular in post-menopausal women, the preparation of the cervix with a hormone administered topically or systemically may facilitate the examination and allow a better interpretation.
Contrary to commonly-held beliefs, this examination is not painful and takes only a short time. I always ask my patients to relax so that they do not contract the muscles of the vagina, which would make the insertion of the speculum more difficult.
How a smear is taken
Women who have already had this examination know that it is quick, and unpleasant rather than painful. When carrying out a patient´s first smear, I first explain the procedure. I also always set the date for the next one if this one is normal.
You settle into the so-called gynaecology position, the bottom flat on the couch. With the thumb and index finger, I part the labia of the vulva and insert the unlubricated speculum along the rear surface of the vagina.
Its insertion should not cause pain. Two models of speculum can be used:
• the Collins speculum which comprises two levers which can be taken apart;
• the Cusco speculum.
I usually use the Collins speculum which parts the vulvar opening and allows me to take samples more easily. If the cervix is difficult to access due to major retroversion or anteversion (where it is tilted either backwards or forwards) or because it is small, I use the Cusco which helps access to the cervix.
Every physician selects the right size of speculum for the anatomy of the vagina so that it can be examined fully up to the cervix. In the post-menopausal woman not on hormone therapy, the mucous membranes are fragile and atrophied. Likewise, the vagina shrinks in a woman who has not had sex for a long time. After radiation (radiotherapy) for cancer, the vagina also becomes more rigid. In all these cases, the examination can be uncomfortable so I prescribe hormones for around ten days beforehand to make the vagina more supple, and I use a small speculum with smaller levers. Likewise, I often choose a disposable speculum as metal can feel unpleasant to some women, but the use of metallic material is necessary for optimum examination conditions. In this case, it is essential to have an approved sterilisation unit.
Generally speaking, I prefer to insert the speculum diagonally so as to avoid pinching the lips when the speculum is rotated through 90°, with the screw pointing downwards. I ask the patient to push when the speculum is introduced (this action is not at all painful), and I then insert it, closed, to the back of the vagina in the direction of the cervix. The two levers are parted to facilitate the search for the neck of the womb which should be seen in its entirety: external opening between the two anterior and posterior lips.
The sample is taken with a flexible brush, wide at its base and tapering towards its end.
The tapered end of this brush can be inserted in the cervical canal with its wide part resting on the external wall to help positioning. I rotate it clockwise three times through 360°. (A wooden spatula can be used to take samples of cells from the outside of the cervix and a cotton bud from the cervical canal.) However, I prefer the triangular brush with which endocervical and exocervical samples can be taken at the same time. If the cervical canal is narrow - as is the case with post-menopausal women, those who have not had children, virgins, women who have only given birth by caesarean or those who have undergone surgical treatments to the cervix such as laser or high conisation - I use a fine rigid brush which can be inserted in the cervical canal so the sample can be taken.
The smear consists of scraping the surface of the cervix, in particular the most receptive zone where abnormalities develop: the transformation zone which is usually found around the cervical opening. This zone always starts at the junction between the two linings that we have already described: the thick one on the outside or squamous epithelium and the fine one in the cervical canal or columnar epithelium. The good quality of a smear is therefore judged by the presence or otherwise in the sample of these three types of cell: those of the squamous lining, those of the glandular lining and, finally, those of the transformation zone. When reading a smear result, if I note that there is no description or presence of cells from the transformation zone or the glandular component, I know that the examination was not optimum and that another one needs to be performed.
This is why I always ask my patients to show me their smear result so that I can assess the quality of the sample.
I do this because, if the transformation zone is in the cervical canal, cells need to be taken from the canal with the most suitable tool: a narrow rigid brush called a cytobrush, which can be inserted into the cervical canal.
An over-zealous sampling procedure can sometimes cause slight bleeding in the twenty-four hours following the examination; do not panic, this is normal if the physician has scraped the mucous membrane firmly or if it has become fragile due to inflammation or a lack of hormones.
At the end of the examination, I remove the speculum gently, with the two levers remaining parted to check the integrity of the vagina walls (this enables any cysts on the vaginal septum, ulceration or warts, called condyloma, to be identified). In order to examine the anterior and posterior vaginal walls in their entirety, I dismantle the Collins speculum and use just one lever in order to push back one of the two walls of the vagina, asking the patient to push. This manoeuvre allows me to see any slackness in the muscles of the perineum around the vagina; the movement of the opposite wall of the vagina could interfere with this. This laxity, called prolapse, can cause organs to descend and affects the zones of the cervix, the bladder which crosses the front wall of the vagina and the rectum which holds the rear wall in place. This mainly affects women who have had a number of pregnancies and who have not undergone any physiotherapy of the perineum.
From start to finish, the smear will have taken less than 5 minutes.
Two kinds of smears used for screening
Two kinds of smears are commonly used:
• the conventional smear or Pap smear, which has not changed for sixty years;
• the more modern, liquid-based smear which has existed for a mere ten years or so.
The conventional smear, an old method which has proved its worth but has limited sensitivity
After taking cells from the surface of the cervix and transformation zone using the brush or the spatula and cotton bud, the doctor spreads this sample uniformly on a glass slide (2 slides are usually made). The slide is then immediately fixed to keep the cells intact.
This step must be undertaken carefully and rigorously in order to avoid any possible pitfalls. For example, a sample can contain very few cells, so there is a risk when they are transferred from the brush to the slide that abnormal cells are not seen. Spreading the sample badly and fixing it badly can also considerably hamper its reading. Likewise, an infection or inflammation, with its large load of white and red blood corpuscles or abundant mucus, can mask the visibility of possible abnormalities.
Each slide then needs to be identified. They are slid into a box and usually sent to the laboratory in a padded envelope intended for this purpose. The result is sent to the doctor on average two to three weeks later. He will then inform his patient in writing, enclosing a copy of the report.
The liquid-based smear, a modern method which opens up many new possibilities
As we have seen, taking a sample using the conventional smear method is not always reliable. A number of factors can adversely affect its performance: the sample may be taken badly, the slides read incorrectly or abnormal cells not recognised when transferred. Indeed, it is estimated that 80% of cells are lost during this transfer, which means that in two-thirds of cases, the smear is ineffective. It should also be noted that it is also possible for the laboratory to commit some errors in interpretation. Thus, a few years ago, the level of defective or poor-quality samples was estimated at 10% in England as against 2% in France.
And last but not least, it is not possible to identify the causal agent of pre-cancerous lesions on the cells of the conventional smear.
This is why it was necessary to offer a new type of smear which would meet these needs.
It is called the liquid-based smear or thin-layer smear.
The sample is taken in the same way but, instead of spreading the cells from the brush onto a glass slide, the entire brush is rinsed in a liquid solution to preserve the cells.
This method allows firstly almost all the cells obtained to be transferred from the sampling implement into the liquid, thereby reducing practically to zero the inherent risk of loss associated with the conventional smear.
Furthermore, this technique, in addition to improving sample quality, eliminates all the components which can interfere with its interpretation (mucus, white and red blood cells etc.). Using a special procedure, the cells immersed in the liquid are drawn out and spread in a “thin layer”.
The advantage of this method lies also in the fact that, where the smear presents cells with minor changes, additional cells can be taken from the suspension in order to test for papillomaviruses - agents which, as we have seen, are responsible for pre-cancerous lesions of the cervix.
There are a number of liquid-based tests on the market, but only two have been validated and can be used in complete confidence. After hearing about the first results of these new smear tests, which come from the USA, I decided to try them in France, in 1998, by coordinating a large study involving six laboratories and thirty-five gynaecologists. This was an ambitious project as some pathologists looked unfavourably upon this new technique which was more expensive than the traditional method and required costly equipment and special training. To do this, I brought together public and private laboratories, specialists in a high volume of activity or more traditional ones, and organisations which were opposed, neutral or favourable to this new procedure so that the study was as representative as possible. During this trial, 5,428 patients had a single cervical sample taken from which cells were spread on slides in the conventional way, the rest of the sample being dispersed in the preservative liquid - a monolayer technique using the ThinPrep method (TP). The two slides from each patient were read double-blind (neither patient nor the tester knew which was which), and where there was any disagreement, an independent expert and a whole panel of pathologists checked them. We concluded that:
• the liquid-based method enabled the detection of high-risk lesions to be increased by 39% over the conventional smear, and the detection of minor lesions by 50%;
• the detection rate of the liquid-based method stood at 83% as against 66% for the conventional smear. The results of this project were published in the international scientific journal British Journal of Cancer in 2001, confirming the data published in the international press.
In August 2001, a clinical trial asked ten hospitals in the United States to compare the two types of smear: 20,917 samples taken by the conventional method were compared with, proportionally, 10,226 samples obtained by the ThinPrep liquid-based technique, followed by an analysis of abnormal tissue (biopsy). For all the positive cases, a 59.7% difference was found in favour of the liquid-based method for immediately pre-cancerous lesions, a conclusion confirmed by biopsy.
Another liquid-based smear process, called SurePath, the automatic version of which in 1999 received FDA approval of equivalence with conventional cytology, has been the subject of numerous publications. The quality improvement in the liquid-based method ranged from 42 to 75%. A multi-centre study showed a 46% diagnostic improvement for minor lesions and 6% for pre-cancerous lesions, while a study involving three laboratories demonstrated a diagnostic gain of 59 and 79% respectively. A few studies contest this diagnostic performance, but all acknowledge the improvement in sample quality with the liquid-based smear technique.
Other liquid-based smear techniques are also available, but there is little in the way of data about their performance and their ability to provide representative cell samples from the cervix. Many of them have also not been validated.
In the United States, 80% of samples are obtained using the liquid-based smear technique compared with 20% in France. However, England has adopted this technique for its national screening programme. Why so few liquid-based smears in France? Simply because it costs more and is not reimbursed by the social security. The laboratories which offer it generally therefore have to absorb the extra costs themselves.
For my part, I have nevertheless adopted this method for all the reasons mentioned above. However, I can confirm that a conventional smear carried out at optimum technical conditions remains valid.
Practical details regarding the screening smear
Once the smear has been taken, I usually give the patient the envelope containing the smear for her to post to the laboratory. Some doctors use a courier service provided by the laboratory to collect these samples. The results, as I have said, reach the doctor by post between two and four weeks after the sample was taken. I am, I repeat, in favour of the patient receiving a copy of her own smear result even if it is normal, as the common practice of only giving the patient her result if it is abnormal seems risky to me. Indeed, I have observed a number of dramatic cases where the patient, not having received the letter because of an incorrect address or postal strike, has not known about the results of an abnormal smear and so has not consulted her doctor, with a fatal outcome some years later, which could have been avoided. Any woman who has not received her smear results one month later absolutely must ask her doctor for them. The physician must likewise keep all abnormal results in a file and thus check whether the patients he has asked to make an appointment have indeed attended for a consultation.
It is essential, upon receipt of the result, that the patient - there and then - makes an appointment for her next smear.
Although, according to French recommendations, the first smear should be performed at 25 years of age (as the number of cancers below this age is insignificant), practice shows that it takes place on average at 20 years. Thus, in the United States, the first smear is recommended two years after the first sexual relations, a viewpoint I totally share. In France, the average age of the onset of sexual activity is 17, and although their capacity for spontaneous regression is real, it is not rare to observe real pre-cancerous lesions in young women under 20 years of age. Indeed, if a young woman is exposed to the papillomavirus when she first starts to have sex at around 14 years of age, a viral lesion can develop within 12 to 18 months and a pre-cancer occur 4 to 5 years later.
Although it is proposed that this screening should stop at the age of 65, I think that it needs to be continued as long as possible, especially where the woman is sexually active.
In France, the frequency at which a smear should be taken has been the subject of much discussion and the fodder of much debate. Do I need to mention the controversy in the 1990s when the social security required doctors to provide an opposable medical reference in order to obtain reimbursement for the smear based on a 3-year testing frequency? This was, of course, for reasons of economy and was supported by the recommendation of the Lille consensus, since it had been demonstrated that, in Scandinavian countries in particular, a smear every three years, in a system where screening was nonetheless organised, resulted in a 95% reduction in cervical cancer. Transferring this finding to our own situation was however to fundamentally ignore the limits and loopholes in our own screening system, and imposing it at a 3-yearly frequency would have been catastrophic in every respect. Firstly, in a country without an invitation system, a lot of women would have been demotivated and would have neglected their gynaecological monitoring. Also, as the conventional smear does not have optimum sensitivity, this overly long interval would make women run the certain risk of developing cancer (over 20% by our estimates). The interval between two smears should be decided on the basis of the sensitivity of the test used. The less sensitive the test, and this is the case with the conventional smear, the more frequent the screening procedures should be. Finally, it was neither acceptable nor logical to transpose the entire performance of an organised screening system to a system based on individual initiative.
I then launched a national survey among gynaecologists to find out what the interval between two smears was for women who developed cervical cancer. How astonished was I at the professionals´ response to this question! 1,200 of them, i.e. 25%, replied in detail to this questionnaire. The survey revealed that in 60% of cases, women with cervical cancer had never undergone this examination or had, in most instances, had their last smear more than three years previously; and in 35% of cases, their smear was normal three years ago. Since then, large international studies have confirmed that, in countries where screening is left up to the individual, a smear every three years increased the risk of developing cancer by 30%.
Bolstered by these results and under pressure from women supported by MPs convinced of the absurdity of this measure, Bernard Kouchner, the Minister for Health at the time, repealed it.
In France, health insurers tell us that, in reality, the gap between two conventional smears is 18 months on average.
After a hysterectomy, however, the vaginal smear should be less frequent.
The results of the smear
From the appearance of the cells, one can establish whether the cervix is normal, whether an infection is present, or whether these are abnormalities which could be pre-cancerous lesions called dysplasias, or even cervical cancer (approximately one woman in 10,000 gets cervical cancer every year in France). But beware: the smear enables abnormal cells to be detected but it is a screening test and not a diagnosis. A diagnosis can only be obtained by biopsy (sampling and analysis of a tissue fragment).
The normal smear
A smear is described as normal where the sample cells do not show any change, other than benign or reactional, which could correspond to or give rise to suspicion of a papillomavirus lesion foreshadowing a pre-cancerous lesion or cancer itself.
Certain infections can sometimes, though not always, be revealed by the smear: fungi (mycoses), trichomonas (parasite of the lower genital tract), herpes (a virus which attacks the external genital organs and more rarely the cervix), chlamydia (microorganisms which attack the cervix, the uterus and the Fallopian tubes and can cause sterility). But the smear is not the best method for diagnosing these infections.
Cervical cells can however undergo changes which remain benign abnormalities. This is because the transformation zone of the cervix is in perpetual motion as it constantly regenerates. This is one of the characteristics of the cervix. This regeneration is also called reorganisation and, when almost complete, it causes changes to the cells which appear on the smear. This is what happens with women who are still menstruating, who have a commonplace infection or who have undergone radiotherapy in this area following cancer. These changes, often not serious, can sometimes appear ambiguous and are called ASCUS. But we will consider this later.
They require additional exploration so that a possible dysplasia is not overlooked.
The abnormal smear, a silent and dreaded evil
A smear is described as abnormal if it is not classed as normal. This definition may seem obvious but what it means is that an abnormal smear covers a range of types and stages of abnormality, from the most commonplace to the most serious.
In the same way as a normal smear is not necessarily synonymous with a normal cervix, as the sensitivity of the smear is not optimum, an abnormal smear can also reveal something which is not serious. An abnormal smear is an alert but in no way a diagnosis. It is a call to be attentive and vigilant and, depending on the cells examined, suggests a follow-up or the need for more extensive examinations.
To understand the different types of smear abnormality, let us think back to the section on “The cervix under the microscope”. We explained where the boundary is between the two linings of the cervix, the squamous, malpighian and the glandular, separated by the junction. From this junction there develops over the transformation zone a dynamic corona of a variable size called which shows the normal repair process under the effect of female hormones. This regeneration is called malpighian metaplasia.
Abnormal changes to the cells of the cervix are always concentrated on this zone, an area which is receptive to the papillomavirus, and in particular on the cells of the junction.
First of all, these changes follow a very slow process which it is possible to recognise in time and treat effectively.
Women then need to know that if they have had smears regularly, the discovery of an abnormal smear hardly ever indicates a cancer but, instead, a benign and always curable process.
Thus, an abnormal smear should not trigger a panic reaction, as is too often observed, and does not mean cancer. The announcement of an abnormal smear without any explanation is a shock for many women.
With the sample, it is possible to observe these abnormal cells under the microscope. They are called dysplasic cells (in Greek dys means abnormal and plasia change).
Initially, papillomaviruses cause localised changes in the cells of the lower third of the lining of the transformation zone; this is known as mild dysplasia or LSIL (low-grade squamous intraepithelial lesion), according to the American Bethesda terminology commonly used. If the changes reach the bottom two-thirds of the lining, this is called moderate dysplasia. And if all levels of the cells of the lining are changed, this is called severe dysplasia. Moderate and severe dysplasia, which often have a homogeneous entity indicating a high-risk lesion, are both called HSIL (high-grade squamous intraepithelial lesion).
Where the cells are changed (which can be metaplasia, a normal process, or dysplasia, an abnormal process), this is called ASCUS (atypical squamous cells of undetermined significance), again per the American terminology.
All these abnormal changes are, in most cases, benign lesions. However, some of these lesions may lead to cancer if they are neglected. Although this process is generally slow, I recommend that there should be no delay and that the necessary examinations should be carried out to establish a precise diagnosis and, if applicable, prescribe appropriate treatment.
I have an abnormal smear, what next?
Above all, don´t panic! Remember that an abnormal smear is the sign of minor or undetermined changes in 80% of cases.
Consequently, if you receive a letter informing you that your smear is abnormal, you must make an appointment to see your doctor so that he can interpret your result and tell you what to do next. Never think that he is hiding the truth from you; this feeling creates unnecessary suspicion and distrust. After reading this book, though, you will be able to deal with this kind of situation calmly.
In France, several thousand women have abnormal smears. Of the six million smears performed annually, around 200,000 are abnormal, yet only half of them reveal confirmed abnormalities and around 65,000 are deemed lesions with a cancer risk if left untreated.
You doubtless know of someone in your family or among your friends who has survived.
However, avoid talking about it with the people around you as this could make you panic. Other people do not necessarily have the same pathology as you or the same doctor. It is extremely important for you to trust your gynaecologist or GP; you should even be critical and talk to him or her about your fears. Do not hesitate to ask for a second opinion from a specialist if you feel the need.
While waiting for this second appointment, you will probably be tempted to look for additional information on the internet. I personally would urge you not to do so - I will return to this issue later - since this would expose you to even more anxiety as it is difficult to filter this information, despite the quality of some sites, and your case is not necessarily like the ones described. Your best advisor is your doctor or specialist; only they can explain what you should do next, and only they can establish a diagnosis and determine the grade of the lesion.
But back to what needs to be done if your smear is abnormal. Very often you will need a colposcopy. This simple, quick and painless examination will enable the abnormality on the cervix or vagina to be shown there and then, the exact topography to be identified and a sample (biopsy) to be taken for a final diagnosis.
Sometimes, your doctor will judge that the changes on the smear are minor and do not justify colposcopy, but recommend this examination be carried out a few months later if your repeat smear, which is always essential, is also abnormal.
Or alternatively, your doctor may decide not to leave you in a state of uncertainty until your next check-up; if your smear was unclear (ASCUS), he will suggest that you request an HPV test on a cervical sample. If the test is positive, he will ask for a colposcopy.
It is colposcopy which allows these diagnoses to be made, as it can make directed biopsies (miniscule samples of abnormal tissue). This is the subject of the next chapter.