I have got a pain under my arm extend in canals to under my brest..sometimes i have got a pain in my arm..is it a sign for smothing like a cancer?

Mammograms are : Important to detect breast lumps so if u have a lump in addition to the pain, then u would need a mammogram. Otherwise u may have a pectoris muscle inflammation perhaps from injury or viral infection. Or a rib issue or referred pain from the shoulder. Since it could be a lot of things, you may need to see a healthcare professional for diagnosis and treatment.