Society, 1981). According to Bryan (1983), the vast majority

of human tumors, about 90%, are carcinomas. And, the

majority of research focusing on psychological and social

variables considers individuals with cancers of this type.

 The amount of resemblance of a tumor to normal cells

and tissue and an estimate of its growth rate are considered

to be important biological factors in the course of the

disease and the potential for cure or control (Meissner,

1978). As Goldfarb (1983) has pointed out, the characteriza-

tion of cells in this way is referred to as grading.

 This issue, that cancer is not one disease but many, is

an extremely important issue not only for biologic research

but for psychological and social study in this area as well.

 The development of cancer. In a broad sense, advances

in the understanding of epidemiologic factors in cancers have

not resulted in a view of a simplified relationship but

rather in an appreciation of a remarkably complex, multi-

staged process.

 According to Meissner (1978), the causes of the meta-

bolic defect in cancer cells are innumerable. Causative

factors may be intrinsic or extrinsic to the individual or

animal developing a cancer. Among the intrinsic factors that

may be casually related are heredity, age, race, sex, and

hormonal and immunological status. Among the extrinsic

agents implicated in the development of cancer are chemicals,