Is redness a common sign of breast cancer?

Not in general. Redness is not a common sign of most breast cancers, but it can be seen in a rare but aggressive type called inflammatory breast cancer. Your doctor can help you distinguish this unfortunate cause of redness from allergic skin reactions or infection.
It can be. Redness of the breast is not usually seen in early breast cancer. But more advanced cancers can cause redness especially a type of cancer called inflammatory breast cancer. You should get yourself examined by a breast cancer specialist right away.

Related Questions

When I itch my breasts they get red, sometimes they feel dry, is that a sign of breast cancer?

Nope. The internet is rife with horror stories about misdiagnosed breast infections & rashes that were actually cancer. The changes assc w/inflammatory breast ca are not transitory--the breast is red & stays red. Likewise, paget's of the breast manifests as a rash on the nipple. What you are describing sounds like dry skin. Of course, at 48 you should be getting yearly mammograms; if you haven't. ..
No. Skin dryness and an itchy sensation of the skin overlying the breasts is not a symptom of breast cancer. Inflammatory breast cancer, a very rare form of the disease, can occur with skin thickening, redness, and a heavy sensation of the affected breast when compared to the other side. However, this would not occur just after scratching the skin.

I have a red blotch on my breast next to my ariola. Is this a sign of breast cancer?

doesn't sound like. It sure doesn't sound like it, but symptoms like these deserve a full evaluation in person by your health care provider, especially when you are concerned about a potentially fatal disease.
Probably not. There's a form of breast cancer called "inflammatory cancer" which presents as red, swollen skin on the breast. Another type of breast ca is padget's disease, but that is usually seen on the areola. Both are rare, fortunately. If the lesion has been there for a while, you should get it checked out. A skin biopsy is the only way to know for certain.
See you doc. You should bring this to the attention of your friendly primary care physician.

I am a 43 year old female. I had breast cancer 14 years ago. I have had a knot in the middle of my chest for years. Now it has gotten red, hard and painful. Why could it be?

Painful knot. This scenario needs medical attention. The lesion could be as harmless as an infected hair follicle but could also be your breast cancer returning. It needs immediate biopsy secondary to your history.
Talk to your doctor. It is unlikely that this is breast cancer recurrence, since it was unchanged for several years and you are 14 years out since diagnosis. However, any change in a cancer survivor warrants further evaluation. I would recommend you follow up with your physicians and have them evaluate it.

I have red spots on breast that are spreading could it be a forum of breast cancer?

Certainly not. Breast cancer almost never presents this way. Some kind of skin problem is far more likely. I would be happy to help you with that if you like.

Bump on breast, red, hard like a grapefruite. What could it be? Breast cancer? It also hurts

Likely infection. In your age group, an infectious process is most likely. There is a very small chance that it could be something more serious. Either way, you need to see your doctor asap for diagnosis and treatment.
Breast lump. Breast abscesses, cysts, and occasionally breast cancer can all present with the same symptoms. Recommend senior physician for further valuation.
Need immediate attn. A lump of this size, regardless of your age, needs immediate evaluation. Contact your gynecologist and ask for a breast specialist. An ultrasound may be helpful.
Could be. What you are describing could be an infected cyst. It also could be a locally advanced breast cancer. Get a good examination and follow up. Workup may include a mammogram, ultrasound, or an aspiration with a needle of the lump.
Possibly. A hard, red, painful mass on the breast certainly could be breast cancer, but in a 19 year old, it is much more likely to be an abscess (infection). In either case, you should see your doctor as soon as possible.
Likely benign. Pain swelling and redness in your age especially is likely infection: mastitis or cellulitis or abscess. Can still be serious so you should see doctor asap.
Breast mass. It needs to be evaluated by your doctor. It could be an infection, a blocked duct or a cancer. There are many things it could be but you need to see your doctor soon.