Referred by doctor to hospital for swollen right lymph node supraclavical and lump in left breast. how likely to be cancer? i'm 23

Possible/unlikely: Any swollen lymph nodes and any breast lump should be evaluated. You are very young and a right-sided node plus a left breast lump are unlikely (not impossible) to be related. I would put you through a thorough history and physical and get some basic blood tests. Then maybe some x-rays depending on the above. To answer your question more exactly would need more info. Good luck!

Lump/lymph node: Any lump on breast warrants further evaluation. A mammogram and sonogram of breast should be done. A biopsy should be done for suspicious lump. The risk for breast cancer is not high- however, other type of cancer like lymphoma or soft tissue cancer can be found and can be presented as a lump on the breast.