I have painful swollen lymph nodes under my arm pits and along the sides of my breasts. should i worry? they have been this way for four weeks. i have no other signs of infection. they are really painful. could it be cancer?

Swollen : Swollen lymph nodes can be a sign of the body fighting local infection, but can also be a sign of a tumor - or cancer- growth in some circumstances. If glands are swollen on both sides of your body, and are uncomfortable or painful, this makes infection a much more likely cause. Skin infections, in the pores and hair follicles ("folliculitis") can cause local infection from common bacteria that are on our skin, and the body will frequently fight this off and resolve it on it's own. Nonetheless swollen lymph glands should be evaluated by your health provider whenever they last more than a few days: only with a complete history and examination can it be determined if you need treatment for an infection (sometimes w/ topical antibiotics on the skin, sometimes oral antibiotic medication), or if more investigation is necessary to determine the cause of the swollen glands.

Yes: It is unusual to have breast cancer causing enlarged lymph nodes without a mass in your breast but not impossible you should see your doctor and have your situation evaluated an ultrasound and mammogram would be helpful in your work up.