This undated photo provided by the American Cancer Society shows Dr. George Papanicolaou, inventor of Pap test, foreground, and his wife, who was also his research partner, in their lab. In the late 1940s, the American Cancer Society advocated wide adoption of the Pap test, which has resulted in a 70 percent decrease in uterine and cervical cancer.

NEW YORK — The American Cancer Society — one of the nation's best known and influential health advocacy groups — is 100 years old this week.

Back in 1913 when it was formed, cancer was a lesser threat for most Americans. The biggest killers then were flu, pneumonia, tuberculosis, and stomach bugs. At a time when average life expectancy was 47, few lived long enough to get cancer.

But 15 doctors and businessmen in New York City thought cancer deserved serious attention, so they founded the American Society for the Control of Cancer. The modern name would come 31 years later.

The cancer society's rise coincided with the taming of infectious diseases and lengthening life spans. “Cancer is a disease of aging, so as people live longer there will be more cancer,” explained Dr. Michael Kastan, executive director of Duke University's Cancer Institute.

Cancer became the nation's No. 2 killer in 1938, a ranking it has held ever since. It also became perhaps the most feared disease — the patient's own cells growing out of control, responding only to brutal treatments: surgery, radiation and poisonous chemicals.

Last year, the organization had revenues of about $925 million. It employs 6,000 and has 3 million volunteers, calling itself the largest voluntary health organization in the nation.

“The American Cancer Society really is in a league of its own,” Kastan said.

The rate of new cancer cases has been trending downward ever so slightly.

Some historical highlights:1913 — The American Society for the Control of Cancer is founded in New York City.1944 — The organization is renamed the American Cancer Society. The change is spurred by Mary Lasker, the wife of advertising mogul Albert Lasker.1946 — A research program is launched, built on $1 million raised by Mary Lasker. A year later, Dr. Sidney Farber of Boston announces the first successful chemotherapy treatment.1948 — The cancer society pushes the Pap test, which has been credited with driving a 70 percent decline in uterine and cervical cancer.1964 — Prodded by the cancer society and other groups, U.S. Surgeon General Luther Terry issues a report irrefutably linking smoking to cancer.1971 — The cancer society helps lead passage of the National Cancer Act to ramp up research money. President Nixon declares a national “war on cancer,” which becomes an extended effort derided by some as a “medical Vietnam.”1976 — The cancer society suggests women 40 and older consider a mammogram if their mother or sisters had breast cancer.1976 — The cancer society hosts a California event to encourage smokers to quit for the day. A year later, the annual Great American Smokeout is launched nationally.

U.S. Surgeon General Dr. Julius B. Richmond, at the center of the microphones, kicks off the third annual “Smokeout” rally sponsored by the American Cancer Society in 1979 in Washington, D.C. as part of the “Great American Smokeout Day.”