There is something in my left breast.its like a small lump but its not painful. is it possible that this is a tumor or a breast cancer?tnx

Breast lump: See pcp to have breast exam & referral for mammogram or ultrasound or mri, especially if there is a family history of breast cancer. May just be fibrocystic changes, but best to be checked. Also check your armpits for lumps. If not already doing it, learn how to self-check breasts regularly.

At age 18...: A small breast lump is most likely a benign finding. Breast lumps occur more often around the menstrual cycle. If the lump persists for a some weeks, then see a doctor for an examination to be sure it is ok.

Probably not: It would be exceedingly rare for an 18 year old to develop breast cancer. You should however speak about your concerns with your friendly primary care physician.