Feeling a lump in the breast is a classic sign of breast cancer, but there are other less-well-known signals that can tip off potential trouble.

"The hope is that women know their own bodies and would find a mass before it becomes palpable, but the truth is that radiologists can find tumors so small — 3, 4 or 5 millimeters — that it’s rare to be able to feel a small tumor before it can be discovered by mammogram," said Dr. Therese Bevers, medical director of the Cancer Prevention Center at MD Anderson in Houston and an expert in breast cancer screenings.

Today, breast self exams are not widely recommended, but that doesn’t mean you should stop investigating your breasts, Bevers said. The keywords now are "breast awareness. You know how your breasts look and feel. If something feels different, have it checked out," Bevers said.

Women themselves discover "a substantial amount of breast cancer because nobody knows a woman’s body as well as she does herself," said Dr. Rachel Brem, director of breast imaging and intervention at The GW Medical Faculty Associates in Washington, D.C.

"Women have to understand that mammograms are imperfect. Fifteen percent of breast cancers cannot be seen on mammograms. The death rate of breast cancer has decreased 35 percent in the past few decades, and mammograms are one part of that. They’re one tool in our toolbox, but there’s other things like MRIs, diagnostic ultrasounds and molecular breast imaging," Brem said. 

"We have many kinds of technology; no one size fits all."

Some of the signs of potential breast cancer:

Red, inflamed breast

A swollen and sometimes warm, red breast should be evaluated promptly, Bevers said. Inflammatory breast cancer is a rare but aggressive disease. Swelling and redness affecting one-third or more of the breast is cause for concern. Smaller changes, like the size of a half-dollar, are probably not breast cancer, "but get it diagnosed," Bevers said.

Peeling, scaling

Flaky, peeling or scaling skin on the breast could be a sign of Paget’s disease, a type of breast cancer, or it could be minor skin irritation, Bevers said. Watch for whether the skin changes only occur in one breast, often starting in the nipple area, and spread from there.

Dimpling of the skin

"A dimpling on the skin of the breast like a pimple that doesn’t heal" can also be a sign of breast cancer, Brem said. The nipple may also become retracted because there’s a tumor pulling it inward, Bevers said. The dimpling might be subtle and noticeable only at certain times, for example, when you stand in front of a mirror and raise your arms to brush your hair, Bevers said.

Nipple discharge

Most nipple discharge is not breast cancer, but it is of more concern if it is spontaneous, from one breast only, or clear rather than milky or greenish, Brem said. Nipple discharge may not have a high suspicion rate, but have it checked out.

Mass in the armpit

An ancillary mass in the region, such as a lump in the armpit, could be breast cancer in the lymph nodes, Bevers said. "Not all lumps in the armpit are breast cancer. It could be an ingrown hair, but it needs to be checked out," she said.

A thickening

If your breast feels firmer than before, that change should be evaluated by a doctor. "If it’s a change to you, it doesn’t matter what you can see or feel," Bevers said. Use your awareness of your breasts. If something doesn’t feel normal, get it checked out.