Mixed HER2 Status in Breast Cancer Tumors: Is This Common?

Hi Julie. I can relate. I have BC in both breasts my tumors that were found within 4 months of each other. One breast is ER/PR positive. The other breast is ER/ Her2-positive. Also rare to have BC in both breasts my tumors are non related. Did your surgeon say if the tumors are in the same quadrant? Ask your doctor because I’m not an expert but it’s to my understanding that If the tumors are in different quadrants that they are independent and can have different subtypes. It is rare from what I was told.

Hi Jenny, thank you for replying! My her 2 positive tumor is right next to my her 2 negative tumor. Very very close together. What is your treatment plan?

My treatment plan is Taxol for 12 weeks with Herceptin. Then Radiation for 5 weeks with 6 more months of Herceptin. I have my 5 th cycle tomorrow. I could complain but it has not been as bad as I thought it would be.

If my oncotype score comes back suggesting no chemo for the her 2 - tumors then I will have the same treatment plan as you without the radiation. Otherwise it will be more aggressive with two types of chemo drugs to fight both types. Just a waiting game right now. I have been dreading the possibility of chemo throughout this whole process.

What you're experiencing with mixed HER2 status across different tumors is indeed less common, but you're not alone in having this type of complex pathology. Many patients in this community have navigated similar situations where different areas of their cancer showed varying characteristics, and connecting with others who understand this journey can be really valuable as you process your results and plan next steps.