Free test kits to help detect early signs of colon-rectal cancer are available at most pharmacies in the metropolitan area this month. The kits have been provided by the American Cancer Society. The test is simple and painless, according to the cancer society.

The American Cancer Society already has given out 50,000 test kits, and about 23,000 people have taken the test so far, the society reports. From those tests the society has found 12 colon-rectal cancer cases, as well as 32 blood-related disorders, according to Lois Callahan, a spokeswoman for the society.

Colon-rectal cancer "will strike more than 1,500 people in the Washington metropolitan area this year alone." Callahan said, and "at least 900 of these people will die of the disease." Experts estimate that 75 percent of the people who die from the disease could be saved through early detections.

The test kit contains instructions and a self-addressed envelope to mail the kit back to the society after the test is taken. All results are confidential, and the cancer society has made arrangements to provide treatment, if necessary, to people who cannot afford it.

Some of the participating pharmacies are Dart, Drug Fair, Giant Pharmacies, Peoples and Rodmans. Many independent pharmacies also are distributing the test. To find out which stores are participating, call 232-6100.