Identical Twin, 38 with breast cancer

tamtal

My identical twin has had a rough month and a half, from a lump they assumed was nothing, to a 4cm tumour. She had her tumour removed yesterday, with clear margins, tests clear for lungs and liver, waiting on lymph node comfirmation (90%sure good), and bone scan results. My sister also was diagnosed 2 years ago with basal cell skin cancer and had a tumour removed from her nose. I am seeing a dermatologist and have an appoint. with my doctor tomorrow to discuss screening for breast cancer. I was wondering if anyone knows of an identical twin that has breast cancer and the risks with an identical twin being diagnosed with breast cancer?

leaf

I'm so sorry your sister was recently diagnosed.  This must be quite hard on you.  

To give you a real number, I'm sure that your family would have to be examined by a genetics counselor.  If your family has a BRCA gene (the far-and-away most common single breast cancer gene) - then your risk is going to be higher than if you don't.  Some families have a LOT of breast cancer, yet test negative for the KNOWN BRCA genes.  This means there are probably breast cancer genes we don't know about. These BRCA genes are thought to be responsible for only about 15% of breast cancers - the rest are sporatic.  Whether they are caused by environmental factors, or by multiple gene mutations - is unknown.  Your twin probably shared a lot of environmental factors, as well as sharing many/all genetics traits.

Genetics counselors are normally found at major institutions.

 I can't give you a number, but the risk of breast cancer  when one twin gets breast cancer and the other does not) in a monozygotic twin  is higher than in the general population.http://www.ncbi.nlm.nih.gov/pubmed/18972750

The incidence in a prospective study of monozygotic twins of patients was approximately constant at 1.3% per year (77 cases), again about 0.7% per breast. At ages older than a patient's age at diagnosis, her mother and sisters have an incidence of 0.3-0.4% per year.http://www.ncbi.nlm.nih.gov/pubmed/11101836

In this paper, monozygomatic twins traded tissue for breast reconstruction !http://www.ncbi.nlm.nih.gov/pubmed/18827632

This study found support for a gene that may be associated with breast density,which in itself is thought to be a risk factor for breast cancer.http://www.ncbi.nlm.nih.gov/pubmed/17627014

BethNY

With any sisters, when one is diagnosed with breast cancer, the other has a high risk of about 50%. My good friend was dx 3 yrs ago, and did genetic testing and was negative. Her twin sister has been very closely monitored, and a few weeks ago was just dx.

Even with genetic testing being negative, you would still be considered high risk. It's important to go over this history with your GYN, and that you begin screening in a high risk group, which would consist of 6 month mammo's and alternating Ultra sounds and MRIs.

You may find more info at www.facingourrisk.org

Naomi12475

Tamtel, Hello!  I'm so sorry that your sister was dx with bc.  I am an identical twin also and I was dx in 2005, stage 3c.  I was afraid for myself back then, but, I was also afraid for my sister.  We are inseparable.  I also have another sister and she is doing fine. They watch my twin very closely, and I am pleased to report, that she is doing fine.  I also had genetic testing done, but, my reasons for having the testing done was because of an unusual surgery that I had  3 years ago....my sister donated her belly so I could have boobs again....anyway...I wanted to make sure she didn't carry the genes because she might end up in the same mess as I did.  I realize genetic testing can't predict the future, but it did help me with the decision to use her as a donor.(Of course....she was very, very persistent.  I'm sure you know how it is, you would probably do anything for your sister as well).  Be there for her and take care of yourself.  I can promise you that it will not only ease your mind, but, your sisters as well.  If you need to talk, or have any questions, please don't hesitate to pm me.  Naomi