The desire for a general cancer detection test which would screen large population groups is an obvious and natural one, but it seems no closer to fulfillment today than when the quest began in earnest over a quarter of a century ago. The advantages of a relatively simple, reliable, and universally applicable laboratory divining rod for cancer similar to the serologic test for syphilis require little amplification.

Numerous tests have been proposed to exploit and measure some alleged characteristics of the cancer patient's blood, urine, body secretions, or immunologic or enzyme systems. Thus far, all the tests have been found wanting for one or more of the following reasons:

1. They have tended to assume that cancer is a single disease, with one or more constitutional common denominators which can be identified and used to form the basis for a general cancer test. Current knowledge suggests that this hypothesis may be unduly naive. The thesis that cancer is made up of a group of diseases of remarkably diverse etiology and behavior, sharing only certain cellular and pathologic characteristics, has yet to be disproved.

2. They have also assumed that the alleged common denominator has two further characteristics:

(a) That it is a direct result of the cancer process per se and not merely a reflection of nonspecific body abnormalities secondary to the tissue destruction, body wasting, etc., associated with malignant diseases.

(b) That it is present in the early, localized, and potentially curable cancer.

Many cancer tests have been discredited or shown to be of no practical value because these assumptions have proved to be unwarranted.

3. Even if cancer tests have met the challenges noted in the first two items, they have been found without exception to be of no practical use in screening programs because of their unreliability. The percentage of false positives and false negatives has been too high to warrant clinical application of the technique.

The search for such a cancer test continues and may yield important information about certain fundamental characteristics of the cancer process, but the day when one of these techniques will simplify the task of finding early cancer seems far off indeed.

In the absence of a single reliable screening test, effective cancer detection depends upon thorough examination of individual patients for the first signs of disease by the use of established clinical methods. In large part, these lend themselves to incorporation into the type of systematized examination which is practical in the doctor's office.

It should be mentioned that many presumably healthy adults will prove to have minimal symptoms which they do not regard as significant. The routine examination of these apparently well individuals serves to bring them to medical attention months or years before they would otherwise have sought it.