How to tell if it's breast cancer in a lump?

Biopsy. The only way to know for sure if a breast lump is cancer or not is with a biopsy - a procedure in which a small amount of the lump is removed and then examined by a pathologist under the microscope. Mammogram, ultrasound and MRI can give a good idea if a lump is cancer or not, and depending on the results of imaging studies, biopsy may not be necessary.
Eval by breast surg. If there's a new lump that's drawing attention/concern, seek immediate medical attention and referral to a breast surgeon. Beyond clinical impression, imaging will often suggest what the lesion is but the most definitive diagnosis usually comes via a needle (i.E aspiration or core biopsy).
Pathologist. The lump should be biopsied or removed and the tissue examined by a pathologist to arrive at the correct diagnosis.

Related Questions

How to tell if it's a breast cancer or other lump?

Breast mass. Other than a biopsy of the lump there is no guaranteed way of telling is something is a cancer or not. Mammogram, ultrasound or breast MRI may indicate the lump has a higher risk of cancer because of shape, calcifications within the lump or reaction around it but none of those are a sure way to diagnose it. Biopsy is still the only way to really diagnose it.
See your doctor. It is very difficult to distinguish a benign breast lump from a cancer for patient and doctor. Depending upon age and physical examination findings, we will often get a mammogram and ultrasound to help evaluate a breast lump, sometimes culminating in a (nonsurgical) needle-biopsy--ultimately, the only way to be 100% certain is to look at the tissue under the microscope.
Biopsy. It often requires a biopsy, needle or open, or fine needle aspirate to differentiate a benign lump from cancer. Please consult your doctor.

How to tell if it's a breast cancer lump or some sort of other lump?

See physician. An experienced physician can often differentiate the lumpy-bumpy normal tissue from suspicious masses. Their exam, combined with your medical history, will guide them to ordering additional imaging and possible biopsy.
Breast lump. You need a clinical breat exam and either mammogram or ultrasound, maybe both. See a doctor/clinic.
Removal. The only sure way is to have the lump removed and the tissue examined by a pathologist.

Can you guys tell me how big is a breast cancer lump?

Depends. Breast cancer can be diagnosed with a not palpable (not able to be felt) abnormality seen on mammogram to a large palpable (able to be felt by a patient or physician) to an obvious mass growing through the skin. This spectrum of presentation can make the diagnosis difficult. See your physician immediately if there are questions.

Breast cancer- how could you tell what is a cancerous lump?

Biopsy. The only way to tell if a lump is cancerous is to get a needle biopsy. If you have a lump, I recommend you see your doctor.

How do I tell if the small lump on my breast is breast cancer?

See a doctor. By yourself, you cannot tell if a breast lump is benign or not. Is it new or changing? Painful or not? You really must see a doctor for a physical examination & likely mammogram and/or breast ultrasound. Do not try to guess yourself without a doctor's exam.
Need 2 C Ur Doctor. It is difficult if not impossible to differentiate a benign breast tumor from a malignant one by exam alone. At your age an ultrasound may be very helpful; ultimately, a (needle) biopsy under local anesthesia in an office setting is the most definitive diagnostic method. I advise you to see your doctor for the appropriate direction.

Could you tell me where in the breast the lumps occur, what they feel like, etc. For breast cancer?

Learn your normal. The best way to tell if you have an abnormality in the breast is to learn your own lumpy breast pattern. Performing breast self exam monthly will get you familiar with your breast tissue. Something that doesn't feel normal to you, should be evaluated by your doctor and a mammogram/ultrasound.

Please explain how to tell what breast cancer lumps feel like and which lumps are nothing to worry about?

That is a good.. But hard question. A lump is a lump, be it benign or malignant. Even a physician may be unable to tell the difference by just palpating. If a lump grows over time, i'd be more concerned that if it doesn't but even that can mislead you. Please, do not self diagnose. Make sure you get your mammograms on time and see your doctor about any and all breast issues that may concern you. Best to you.