SMOKING AND CANCER
Smoking today stands indicted as a significant factor in
many types of cancer, most notably cancer of the lung. Most researchers believe
that there are multiple causes, rather than some single cause, for cancer.
Many
believe that certain human cancers will be proved to be due to viruses which
already are known to produce some cancers in animals. No matter what the cause
may be, the basic cancer process involves a change in DNA or RNA, chemicals
that are part of the reproductive mechanism of cells.
As a result of the change, the cells no longer reproduce in
orderly fashion but divide rapidly and, upon dividing, each cell may produce
three or more new cells instead of the normal two. Whether a virus is the cause
or chemical disturbances are involved, the effect is upon the cell reproductive
system.
And many contributory factors may open the way for cancer by disturbing
the balance between viruses and cells or by upsetting chemical processes in
cells. Thus, sun- light, soot, and other irritating substances are known to be
factors in provoking skin cancer; radiation is known to be involved in
leukemia; and cigarette smoke in lung cancer.
Lung cancer today is the leading cause of death from
malignancy in the United States. Before World War I, 371 deaths in the United
States were attributed to lung cancer. By 1940, there were 7,121; by 1950,
18,313; by 1960, 36,420; and recently the rate has reached 55,300 a year. The
increase has been epidemic in its proportions. The association between smoking
and lung cancer has been established by many studies.
One of the largest
involved a follow-up of more than one million men and women for a four year
period. The study determined that the risk of dying from lung cancer for men
aged 35 to 84 who smoke less than a pack a day is 6 times as great, and' for
men smoking
Smoking more packs 16 times as great, as for nonsmokers.
