Mammography is the best screening process currently available for breast cancer. The mammogram produces an image of the breast tissue where benign or cancerous masses are detected.

Mammography guidelines are as follows:

• A mammogram should be obtained between the ages 35 and 40 to establish a baseline (of the breasts against which future conditions can be measured).
• The Journal of the American Medical Association recommends yearly mammograms for women ages 40 and older. About 29,000 cases of breast cancer are diagnosed in women between ages 40 and 50 each year, while 33,000 cases are diagnosed in women ages 50 to 60. Because the number of breast cancer cases is nearly equivalent in both age groups, it makes sense to have annual mammograms beginning at age 40. Tumors in young women grow quickly. Annual mammograms could diagnose tumors early enough to save lives.
• Every year after age 50.
• Annually if she has had any type of breast cancer, no matter what her age.
• If she has had a sister or mother diagnosed with breast cancer, she should have mammograms beginning 10 years earlier than the age at which her family member was diagnosed.

Abnormal results of mammograms include a group of small, white dots and a star-shaped suspicious mass or nodule. Benign (noncancerous) tumors or cysts appear to have smooth, clear margins. Ultrasound testing uses sound waves to detect whether a mass is solid, cystic or filled with fluid. A cyst creates a dark shadow on the ultrasounds image.

The Mammography Quality Standards Act requires all mammography centers to be certified by the Food and Drug Administration (FDA). Ask to see proof of accreditation to be sure equipment and training meet American College of Radiology standards. All should display FDA certificates.

Positron Emission Tomography (PET) and Magnetic Resonance Imaging (MRI) scanning are other techniques available in certain areas of the country. Both techniques are used as diagnostic tools before biopsy. MRI is being evaluated for detecting early recurrences in women who have had lumpectomies.

Books We Recommend on Breast Cancer

''Women's Cancers'' How to Prevent How to Treat Them How to Beat Them, Kerry A. McGinn, R.N. N.P. and Pamela J. Haylock, R.N. $16.95

''Breast Cancer The Complete Guide,'' Yashar Hirshau, M.D., F.A.C.P. and Peter I. Pressman, M.D., F.A.C.S. $14.95

''Dr. Susan Love's Breast Book,'' Susan M. Love, M.D. with Karen Lindsay $17.00