WASHINGTON -- Mammograms at 40 or 50? Every year or every other year? What's the best colon check?

Screening for cancer has gotten more complicated in recent years with evolving guidelines that sometimes conflict. Now a doctors' group aims to ease some confusion -- and encourage more discussion of testing's pros and cons -- with what it calls advice on "high-value screening" for several types of tumors.

Too often, even the doctors who order those tests aren't sure of the latest recommendations, said Dr. Wayne J. Riley, president of the American College of Physicians, which published the advice Monday in the journal Annals of Internal Medicine.

Breast cancer

The American Cancer Society long has recommended annual mammograms starting at age 40. The U.S. Preventive Services Task Force, which advises the government, says to get mammograms every other year from age 50 to 74.

The ACP sided with the more conservative approach, saying even experts who prefer mammograms at 40 agree women should be informed of the pros and cons to help them decide.

Colorectal cancer

Colonoscopies, which allow doctors to see precancerous growths in the colon, get the most attention. But the ACP advised people ages 50 to 74 to choose from a stool test every year; a colonoscopy every 10 years; a sigmoidoscopy, which views the lower colon, every five years; or a combination of a stool test every three years and a sigmoidoscopy every five years.

Cervical cancer

Screening choices vary by age. The ACP found widespread support for a Pap test every three years starting at age 21. Starting at age 30, women may choose a combination of Pap and a test for the HPV virus that causes cervical cancer, a combination that lets them go five years between tests.

There's little value in continuing to test women older than 65 who were screened and had no problems.

Prostate cancer

PSA blood tests are highly controversial, with some groups recommending against them. The ACP's advice: Doctors should tell men ages 50 to 69 about the pros and cons and order the test for those who request it.