When breast cancer has grown to a size that it can be felt, the most common physical sign is a painless lump.

Breast cancer typically produces no symptoms when the tumor is small and at its most treatable stage. That fact is the reasoning behind getting screened and early detection.

“When breast cancer has grown to a size that it can be felt, the most common physical sign is a painless lump,” according to the American Cancer Society. “Sometimes breast cancer can spread to underarm lymph nodes and cause a lump or swelling, even before the original breast tumor is large enough to be felt.”

Breast cancer, of course, begins in the breast tissue, which is made up of glands for milk production, called lobules, and the ducts that connect the lobules to the nipple. The remainder of the breast is made up of fatty, connective and lymphatic tissue.

Most masses are benign, or not cancerous. Some breast cancers are called in situ because they are confined within the ducts. But most breast cancer is invasive. The seriousness of invasive breast cancer is strongly influenced by the stage of the disease. There are two main staging systems for cancer.

The TNM classification of tumors uses information on tumor size and how far it has spread within the breast and nearby organs.

A simpler system used for staging of cancers is known as the Surveillance, Epidemiology and End Results (SEER) Summary Stage system and is more commonly used in reporting by cancer registries and for public health records.
Breast cancer is the most common cancer among women, accounting for nearly one in three cancers diagnosed in U.S. women.

The American Cancer Society has set guidelines for early detection stating that women ages 20 to 39 should have clinical breast examinations at least every three years and doing a breast self-examination is optional. Women over the age of 40 are encouraged to receive an annual mammogram, an annual clinical breast examination and a breast self examination is optional.

Since the disease shows no symptoms in its early stages it is critical for women to follow the screening guidelines.

“Less common signs and symptoms include breast pain or heaviness; persistent changes to the breast, such as swelling, thickening or redness of the breast’s skin and nipple abnormality such as spontaneous discharge, erosion, inversion or tenderness,” according to the 2011-2012 Breast Cancer Facts and Figures published by the American Cancer Society.

A physician should evaluate any persistent abnormality in the breast as soon as possible.

The National Cancer Institute estimates that approximately 2.6 million women with a history of breast cancer were alive in January 2008. Most of those were cancer free while others still had evidence of cancer and may have been undergoing treatment.

All women should become familiar with both the appearance and feel of their breasts to detect any changes and report them promptly to their physician.

Although the American Cancer Society no longer recommends that all women perform monthly breast self-exams, women should be informed  about the potential benefits and limitations associated with the self exams.