How Cancer Is Diagnosed

In the foregoing chapter we have sketched some facts about cancer as it affects populations. In this and the following two chapters we shall deal with cancer as it affects individuals.

We have stressed the diversity of entities that comprise cancer. This diversity probably precludes the discovery of a single reliable laboratory procedure or test that would diagnose all cancers. We can say certainly that there is no such test known at present. Depending on the suspected site or type of cancer, as based upon the patient’s complaints or the physician’s suspicions, a different set of diagnostic procedures is undertaken. The last of these steps, the basis upon which all diagnosis of cancer is acceptably founded, is the examination of a relevant piece of diseased tissue under a microscope. This is called a biopsy.

For cancers of the internal organs, the steps between initial suspicion and definite diagnosis may be many and complex. The steps are targeted at three questions a physician must answer in considering a patient’s problems. These questions are : what is it? (diagnosis) what should be done? (therapy) ; what is the probable outcome? (prognosis). Cancer is always a medical challenge because the life of the patient depends upon the earliest diagnosis and the correct first treatment.

The most curable cancers are cancers that have not progressed to the stage of producing symptoms. For this reason, periodic examinations of individuals without symptoms is well worth while for the earliest clinical detection of some cancers. Such examinations will not detect all cancers, and many procedures that must be employed in the face of symptoms simply are uneconomical to consider for symptomless individuals. Economy here is not used in the monetary sense, but as it relates to the time, discomfort, and hazard to the patient.

Examinations that have stood the test of experience as being worthwhile in the detection of symptomless cancer include a general physical inspection and palpation of the whole body, with special attention to the cavities of the mouth, the vagina, the bladder and the rectum. The vaginal smear test for cervical cancer should be a routine annual procedure on all women of adult age. If this test were performed on all women, the mortality from this important cancer site could be reduced by about 90 percent. The examination of the rectum by means of lighted tubes, called proctosigmoidoscopy, is also unquestionably useful in detecting this common form of cancer at stages that are curable by surgery.

Under conditions as they exist at present, most cancers are diagnosed because an individual becomes aware of certain symptoms, or because a physician suspects that certain symptoms or signs of a patient may mean that a cancer is present. What are these symptoms? The number is legion, but some are of particular importance and should be considered as danger signals that need early medical attention. None of these symptoms means that cancer is necessarily present, because they could be due to many other causes, but they must not be ignored. The danger signals include the following :

(1) Any sore that does not heal or increases in size, particularly on the lips, tongue, ears, eyelids, or the genital organs.

(2) A painless lump or thickening that persists, especially in the breast, tongue, lips, neck, arm pit, or groin.

(3) Bleeding or abnormal discharge from any body opening, especially the mouth, rectum, vagina, or bladder.

(4) A change in bowel habits, particularly after the age of 40.

(5) Persistent hoarseness or sore throat.

(6) Persistent indigestion.

(7) Unintended loss of weight, continued unexplained fever, or a feeling of weakness.

(8) Progressive changes in the color or size of a wart, mole, or birthmark.

(9) Persistent headache, sinusitis, or difficulty in vision.

Confronted with these or a myriad of other possible symptoms, the physician begins a time consuming, systematic detective action that has three main divisions: a careful history, which may allow a patient to recall events that may be of utmost relevance to his situation; a thorough physical examination, including the use of instruments through which the physician can see parts of the intestinal, respiratory and the genital and urinary canals; and laboratory procedures, especially Xrays. All these may lead to the identification and localization of a mass or a “lesion” which can be reached only by a surgical operation. This is often the case not only for such internal cancers as of the lung, stomach and other organs of the abdominal cavity, but of the breast, muscle or bone. The more favorable cancers are the ones that cannot be distinguished from other diseases before an actual biopsy is obtained. The small piece of tissue that is removed is placed in a preservative, cut in very thin slices, placed on a glass slide, stained with special dyes, and examined under the microscope. The procedure may be done in the operating room, by rapidly freezing the tissue, so that the operation can be continued if the presence of cancer is established.

For specific sites and types of cancer, a wide variety of laboratory procedures are useful in diagnosis and subsequent observations on patients. Some cancers, as part of their biology of abnormal growth, also overdo the functions of the tissue from which they are derived. Tumors of the pituitary gland may secrete too much growth hormone so that the patient develops overgrowth of his bones and other evidences of acromegaly. Tumors of the adrenal gland may oversecrete cortisone and related hormones and produce a physical appearance called Cushing’s disease. Women may start growing beards and in other ways become masculine with certain rare tumors of the ovary, and excrete grossly increased amounts of sex hormones in the urine.

The cytology test, developed for cancer of the uterine cervix, has been extended usefully to other locations in the body. Detection of abnormal cells in the urine is helpful in the diagnosis of cancer of the urinary bladder. Abnormal cells are looked for also in sputum, smears of the nose and mouth, and in washings of the stomach. Cytologic evidence alone is selom conclusive, however, and should be followed by an actual biopsy for the definite diagnosis of cancer.

Thus, the diagnosis of cancer is reached by a pathologist looking through a microscope at a small piece of stained tissue. In order to reach the correct answer, two elements are demanded : the tissue on the slide must be taken expertly and from the right spot, and the man looking into the microscope, must have the experience and the judgment for the interpretation, on which the outcome of the case must depend. It is immediately obvious that human error is inevitable. For some common forms of cancer this error is almost negligible, especially if the lesion is not in its earliest stages. But for other, rarer cancers, such as bone sarcomas, melanomas and lymphomas, the margin of error may be considerable, even on such a basic point as whether it is a malignant tumor at all.

Here often is the explanation of the miraculous cure claimed by a quack. A lesion that is diagnosed as cancer that is not a cancer is curable by any, or no, treatment. Here is also the tragedy of recurrence and wide spread of a disease that was considered to be a benign one. Fortunately, these occurrences are not frequent, and become less frequent as the training and the experience of physicians and pathologists improve. It is also true that difficulties in diagnosis will increase as patients bring smaller and earlier lesions to the attention of physicians, and as the physicians confront the pathologists with progressively earlier stages of cancer.