I was detected with left breast cancer ER PR negative her 2 positive. 1 out of 22 lymph nodes was cancerous. But my first PET showed a lesion in rib (back) SUV 2.9. Doctors were unsure it is Metastic or due to some injury or prior sickness. After chemo lesion decreased to 1.8 with complete regression in metabolic activity. Still I cudnt get a clear answer wat it is. On Dr said single rib lesion is not Metastic ñ can b controlled by herceptin. One said lesion less than SUV 3 is not Metastic ñ herceptin will work. Now plz I need clarification wat this lesion cud mean ñ wat happens after herceptin stops. I am scheduled for 12 cycles of herceptin till now. Can this lesion form cancer?