Читать книгу Cancer is a Word, Not a Sentence - Miriam Stoppard - Страница 12

In most cases, one of the three routes that we’ve just described will lead to your clinical team organising a biopsy, a sample of the suspicious tissue or portion of the organ in which the abnormality has been detected. Biopsies are relatively straightforward.

The word biopsy simply means taking a piece of tissue. There are many ways in which that can be done, and it depends on the part of the body in which the problem is situated. For example if there is a lump in the breast a biopsy can be taken with a thin needle after a little local anaesthetic. The procedure is minor and takes only a few minutes. However, a biopsy from a problem area in the brain is considerably more complex. It requires a proper operation with a general anaesthetic and may take an hour or longer.

In the case of many of the organs inside the abdomen, a biopsy can be taken during a laparoscopy. Usually done under general anaesthetic this procedure does not require a full incision and involves only inserting a thin telescope through the abdominal wall, by which a biopsy can be taken. There are different ways of doing the same thing depending on the part of the body involved. For instance, during a bronchoscopy, the surgeon will examine your lungs and bronchial tree with a thin telescope called a bronchoscope, then slot fine tweezers into the bronchoscope and take a piece of tissue from the wall of a bronchus, one of the tubes that conduct the air into your lungs. During colonoscopy, a similar method is used to take a biopsy from your colon (large bowel) or rectum. Similarly, it is possible to look at and take a biopsy from the structure in the middle of the chest, between the lungs and around the heart, called the mediastinum. That procedure is called a mediastinoscopy.

Depending on the exact site of the suspicious area, sometimes you may need to have a separate operation for the surgeon to get an adequate sample of the area. So you may need to have a laparotomy (an operation in which the abdomen is opened) or a thoracotomy (opening the chest to allow access to the lungs or the heart or the mediastinum) or, in the case of the suspicion of a brain tumour, a craniotomy (opening of a part of the skull to allow access to an area of the brain).

In some areas, sufficient information can be obtained from the suspicious area or lesion by using a thin needle and taking a thin core of the tissue. This is called a needle biopsy. Using an even finer needle and sucking out some cells from the tumour is called a fine needle aspirate and may, in some circumstances, give enough information to plan further tests, including a larger biopsy.

The bone marrow is in some ways a special case. The bone marrow is where the cells in the bloodstream are produced. When there are malignant cells in the bloodstream, as occurs in the various types of leukaemia and some other conditions, a bone marrow sample is taken. Sometimes this consists of inserting a fine needle into the bone marrow inside the pelvis. The needle goes in—under anaesthetic, of course—near the top inside part of the buttock area and a sample of the cells is sucked out. In other circumstances, an actual piece of bone marrow, including the inner surface of the bone, may be needed. This involves basically the same type of procedure but with a slightly different needle. In any event, you can think of these bone marrow tests as, basically, biopsies of the blood-making site.

WHAT A TISSUE DIAGNOSIS MEANS

In the great majority of cases—there are a very small number of exceptions—the whole plan of treatment and the discussions about your condition and your plans, is based on the pathologist’s examination of the biopsy under the microscope. That is what is meant by the phrase tissue diagnosis, having the actual cancer cells under the microscope. Broadly speaking, there are four main clinical settings possible with the biopsy.

First, a biopsy has been taken and the result is clear. This is the most common situation. You have had a lump in the breast. Or a bronchoscopy was done to investigate a shadow on your chest x-ray and an abnormality was found. The pathologist will examine a piece of the abnormal area. In most situations this process takes a few days. Remember, now, what I’ve said before about the way cancers behave and the rate at which they change. Although a few days may feel like a very long time, it is of enormous importance that the tissue sample be carefully examined, and it is genuinely worthwhile taking the necessary amount of time to ensure the result is trustworthy. As one of my patients said about the expertise of the pathologist, ‘You need a really good map-reader in order to trust the “You Are Here” sticker.’

In the majority of situations, the result of the biopsy is conclusive. The pathologist’s report analyses literally dozens of different features of the cells and can state with certainty whether or not there are cancer cells present and, if there are, the way they are arranged. The pathologist analyses many features about the cells’ appearance, important features that have been shown partly to predict how the cancer is going to behave.

The most important of those features are usually:

The type of the cancer, meaning which tissue it started in. This is important because, for example, cancer of the breast that has spread to the lung still behaves like cancer of the breast and is sensitive to the kind of treatment used for cancer of the breast. If cancer of the lung has spread to the bone or the liver, for example, it will still behave like cancer of the lung.

The type of tumour is also significant, and there are many subtypes of tumour. Examples include whether the cancer is forming glands, makes mucus, whether the cells are small (very important in lung cancers and lymphomas), or flat like skin cells (squamous). Sometimes (but not always) the subtype of the cancer influences the way it behaves and this may help decide how the cancer should be treated (its response to chemotherapy, for example).

The size of the cancer, and—for some kinds of cancer, for example, the bowel and the uterus—how deep into the surrounding normal tissue it invades. The pathologist may be able to determine the depth of invasion, which may make a huge difference to the whole treatment approach (in uterine cancer, vulva cancer and melanomas, for example). She or he may also look at whether the cancer has spread into lymph vessels or capillaries or into nearby lymph nodes. If a specimen has been removed surgically, the pathologist can check the margins and if cancer is still present at the borders, more surgery may be needed.

The grade of the cancer, meaning how aggressive it looks under the microscope. The way a cancer is graded varies from site to site. Pathologists all over the world look at certain standard features of the cancer cells and can correlate these with the way the cancer behaves, as a result of large numbers of research studies looking at those features and the outcomes. For example, they look at how many features of the original normal cells are still there in the cancer cells. If most of them are there, the tumour is well differentiated or low grade. If very few original features remain, the cancer is poorly differentiated or high grade. Low-grade tumours usually grow more slowly and have a lesser tendency to spread. High-grade tumours are usually more aggressive and have a greater tendency to spread to other parts of the body and may be under the microscope invading through normal barriers (basement membranes) or into blood vessels of lymph vessels.

Some features are common to most cancers—for example, very big nuclei occupying most of the cell, and many cells being seen in the process of reproducing—and the pathologist will measure the size or rate of these features. But some features are specific to a particular type of cancer cell. So the grading system for cancer of the breast, say, is similar to, but not the same as for brain tumours.

Usually, the pathologist can also determine much more than that. She or he can take slides of the tumour and stain them with different antibodies that bind to different kinds of molecular patterns on the cancer cells. For example, special stains can be used on breast cancer to see if there are oestrogen or progesterone receptors on the cells; if these are present, hormone therapies have a high chance of being effective. Stains can also reveal other molecular groups. For example, again in breast cancer, if an antigen (molecule) called her2/neu is present, the pathologist knows that the cancer may grow more quickly, but also that the cancer cells are susceptible to the drug Herceptin (trastuzumab). Some of the many other stains used by pathologists are to detect: mucin, which may indicate certain types of bowel, stomach and ovarian cancers; cytokeratin-7 and cytokeratin-20, often found on colon and ovarian cancer cells; CEA, found in many colon cancer and breast cancer cells; calretinin, found on the rare cancer, mesothelioma; and melan-A, found only on melanoma cancers.

With most biopsies, the pathologist can determine clearly what type of cancer is present and how aggressive, or what grade, it is. Sometimes, however, the result isn’t clear, and this can be very upsetting to you and your family. So let’s take some time to discuss what ‘We don’t have the full answer yet’ actually means. This brings us to the second clinical setting after a biopsy.

Second, a biopsy has been taken but the result is not clear. ‘You’ve got the piece of abnormal tissue right there under the microscope. Why can’t you tell what it is?’ When you first think about it, it might seem that a biopsy should always yield a definite and certain answer. But there are several situations in which a definitive answer isn’t clear. Think of analysing handwriting. If the sample of the writing includes a variety of letters and flourishes, the analyst may well be able to identify the writer. But if the sample is only a fragment, it becomes increasingly difficult.

It’s worth considering a couple of examples, because this result, naturally enough, causes so much distress.

There are some cancers that under the microscope appear to be so dormant and slow growing that it is actually difficult to determine whether they are truly cancers or not. One example is borderline tumour of the ovary.

In other cases, the cancer cells may have lost so many of the features of the cells from which they originated that it is not possible to say with certainty where the tumour started. In fact between 5 and 10 per cent of all cancers fit into this category and some are known as cancers of unknown primary—it can be seen that the cancer cells form little gland-like formations or have other features, but have lost all of the identifying features of the tissue that they started from (e.g., lung, bowel or breast). It’s important that you know about that, because many people, when they hear the diagnosis of unknown primary, think that this simply means the pathologist is not very good.

In an increasing number of cases these days, much more information can be gained by using special stains. If the cells have oestrogen receptors, for example, it is quite likely that the cancer originated from the breast.

Third, a biopsy has not yet been taken and the diagnosis is based on the results of a test. If one of the tests that you had suggests a cancer diagnosis but a biopsy has not yet been done, then this period of waiting is naturally going to be filled with anxiety. It can hardly be otherwise. As one patient put it, ‘It’s the feeling of not having anything to go on that knots you up. You almost long for news, whether it’s good or bad, because it’s better to know than not know.’

Almost everybody can understand those types of feelings. If you don’t know whether there is something serious going on or not, then you don’t know how to prepare yourself, or even what to prepare yourself for. You are genuinely in a kind of limbo.

There are only two questions that may help you get things into perspective.

The first is how strongly did the test result—the x-ray or scan or blood test—suggest a cancer diagnosis?

The second is when is the next step—the biopsy or other test—being done?

If you can focus on the answers to these two questions, you may be better able to cope with those queasy feelings of uncertainty that will probably creep up on you from time to time.

It is better to focus on the day-to-day events at this stage, than to start worrying, or researching, or surfing the internet about the way in which the cancer would be treated, if that’s the diagnosis. If you are mired in uncertainty—and everyone knows how very unpleasant that is—then you’ll be better off acknowledging that uncertainty than driving yourself crazy by drawing up plans for each eventuality. Of course waiting is a really uncomfortable experience, but if you can see that for yourself and can acknowledge how uncomfortable it makes you feel, you can, to some extent, contain the anxiety, and at least draw a line around it. Acknowledging uncertainty usually helps your coping strategies. Denying the feeling usually doesn’t.

Fourth, a biopsy cannot be taken. There are a very few areas of the body where the process of taking a sample of tissue is so hazardous that a biopsy can’t be done safely. Although this situation is rare, it does apply, for example, to certain crucial areas of the brain, particularly the brainstem, which is the stalk-like back part of the brain and forms the major highway controlling and conducting almost all information from the body to the brain. Injuries to the brainstem would be so devastating that most types of biopsy are too hazardous. If there is a suspicious lesion in that area, it will usually be treated as if it were a brain tumour, even without a tissue diagnosis. There are a few other situations like that, but they are rare. In these uncommon situations, often the treatment plan has to be based on imaging—CT or MRI or some other scan—without a tissue diagnosis.