Medical exams for cancer will be free to every resident of the District of Columbia under a local American Cancer Society program aimed at changing the District's position as the national leader among states in the rate of cancer deaths.

The program of free colorectal exams, pap smears, mammograms and other tests at District hospitals will be financed by a $500,000 anonymous bequest of a District woman who died two years ago, according to Joseph Pollard, president of the D.C. division of the American Cancer Society.

The screening, which will begin immediately, will be free, regardless of income. The project took two years of planning with hospitals and doctors "so as not to disturb the current medical system," Pollard said.

The screening is designed for people with no cancer symptoms. Anyone having one of cancer's early warning signs should see a private doctor or public health clinic rather than visiting a screening center, officials said.

If demand exhausts the bequest, other Cancer Society funds will be tapped to continue the screening, Pollard said, as the effort is expected to find many cancers at an early, treatable stage.

"This screening will go on indefinitely," he said. "We want the people of the District who have been afraid to come in to know that cancer is not a death sentence."

The citywide effort will be publicized by bus placards, posters and radio, television and print advertisements. "This is the city that has the highest mortality from cancer in the country and we want to change that," noted Dr. George Jones, a D.C. urologist and society board member.

The participating hospitals have agreed to charge the society $30 to screen each person for cancer of the mouth, throat, breast, colon and rectum, as well as cervical or prostate and testical cancer. The society will pay $50 for each mammogram. Both rates are about a third of what private doctors charge, according to society officials.

The hospitals and the D.C. Commission of Public Health will administer the program and the society will pay the bills, Pollard said.

Although the program is aimed at District residents, no one will be turned away from the screening, according to Dr. John Lynch, a society board member. Residents of Virginia, Maryland and other states will be asked to mail a donation after the tests are performed, but no attempt will be made to collect the suggested donation.

The donor, who asked in her will that she not be named, requested that her estate be used by the cancer society for "community service" work. Her family no longer lives in the area, according to Pollard.

According to National Cancer Institute figures, the District of Columbia has a cancer death rate of 309 cases per 1,000 people, a rate that leads the country. Rhode Island ranks second and Florida third.

"It may be dietary, it may be environment," Jones said of the District's high mortality rate. "Certainly Washington doesn't have the industry or manufacturing that often promotes cancer. But certainly there is a lot of alcohol use in the District."

Lynch added, "Whenever you find poverty and poor life style, you'll find cancer of the esophagus, lung, cervix and colorectal cancer."

The program also is intended to encourage local doctors to perform more cancer screening tests on their private patients.

"We're looking at the ripple effect through the notoriety," Lynch said.

Individuals interested in being screened are asked to make appointments by calling special numbers at the Washington Hospital Center (541-6710), Howard University Cancer Center (636-7610) or Providence Hospital (269-7986).

Mammograms are available at five locations for all women 35 years and older. Women must have a manual breast exam first, either at one of the screening centers or through private doctors, and be referred for the test. The locations include the Betty Ford Breast Diagnostic Center at Columbia Hospital for Women, Howard University Hospital's Department of Radiology, Metropolitan Radiology Associates' centers on Georgia Avenue and at Providence Hospital and the Washington Hospital Center.

"Contrary to what people think, you can pick up cancer in the breast before you feel a thing," said Lynch. % FREE CANCER SCREENING TESTS

Examinations include:

*Mouth and throat: visual and manual exam of roof, floor, gums and sides of mouth; tongue, face, and neck.

*Breast exam: Manual exam for those over age 20. For women over 35 includes breast X-ray (mammogram).

*Colon and rectum: For those 40 and older, a digital rectal exam and stool blood test.

*Prostate: For men 50 and above. Urine dipstick and digital rectal exam.

*Testes: For all males; visual and manual exam of genital area.

*Cervical: A pelvic exam and pap smear for women 20 and above, or younger if sexually active.

All patients under 18 must have written consent of parent or guardian. Testing should take 30 to 40 minutes.

For appointments call the following numbers. Evening and Saturday hours are available for the tests:

*Howard University Cancer Center 2041 Georgia Ave. NW.

Call 636-7610 from 9:30 a.m. to 4:30 p.m., Monday through Friday.

*Providence Hospital 1150 Varnum St. NE.

Call 269-7986 from 8:30 a.m. to 7 p.m., Monday through Friday.

*Washington Hospital Center 110 Irving St. NW.

Call 541-6710 from 9 a.m. to 4:30 p.m., Monday through Friday.