Final answer:
The most reliable method for early breast cancer detection, before a mass is palpable, is through a mammogram, often supplemented by MRI for younger women. Annual mammograms are recommended for women over 50, while regular breast self-exams are advisable for younger women.
Step-by-step explanation:
The most reliable means of detecting breast cancer before a mass can be felt is through a mammogram. Mammograms have limitations, as they cannot diagnose a malignant tumor, but they can indicate the presence of a lump or areas of increased density that warrant further investigation. For younger women with denser breast tissue, contrast during mammography can be poor, affecting the test's sensitivity. As a supplemental tool, Magnetic Resonance Imaging (MRI) can be used alongside mammograms to improve detection rates and reduce false positives. For women 50 years and older, routine screening mammograms are recommended annually as their breast tissue typically has more fat, providing better contrast for detecting abnormalities.
Breast self-exams are also encouraged for younger women as a monthly practice to familiarize themselves with their normal breast tissue and to be alert to any changes. It is important to note that final diagnosis for breast cancer often requires additional tests beyond imaging, such as tissue biopsies.