Wednesday, March 17, 2010

Genetic testing

I've been back down to The Heath in Cardiff today to see the Medical Genetics team to discuss testing to see whether I have either of the two gene abnormalities that have so far been identified as increasing the risk of breast (and ovarian) cancer. These are called BRCA1 and BRCA2 (literally BReast CAncer 1 and 2).

We went through my family history and agreed that me, mum and gran all having breast cancer does put me into the 'high risk' category. There are 3 categories:
- High, means that you will be offered annual screening between the ages of 35-50, reducing to every 18 months after that.
- Moderate risk, means screening starts at 40, and
- Normal means you join the usual national screening programme at 50.

The counsellor explained basic genetics to me. We each carry pairs of genes and inherit one from each parent. So if my mum (for instance) had one 'good' BRCA gene and one 'abnormal' one, I have a 50% chance of inheriting the bad one. So does my brother. I'd inherit the other one of my pair from my dad, but as there is not any massive history of any cancers on that side of the family, the likelihood it has come down that path is too low to worry about.

So I have agreed to be tested, as I would like to know in order to help me make decisions - in particular, whether to have a 'prophylactic' (or elective, risk-reducing, preventative) mastectomy on my healthy boob when I go for reconstruction.

Being identified as having one of these genes means that your lifetime risk of getting breast cancer is 50-80%, and of getting ovarian cancer, 10-40%. This is versus the 'normal' risk in the population of getting breast cancer of 10-11% and ovarian cancer of 1-2%. So it is a significant increase, but still not an absolute.

Having a mastectomy (or having your ovaries removed, called an oopherectomy) significantly reduces the likelihood of developing it in the future, but does not elimiate the risk entirely.

If we find I don't have the gene, it is highly unlikely that my brother carries it either. It is much more likely that me, the one wot has had breast cancer, would be a carrier than someone who hasn't had any cancers. However, if I do have a gene, he could also have it and will need to keep a closer eye for prostate cancer, and his daughters, my neices, will fall into the 'moderate risk' category and could be eligible for additional screening. But lets not worry about that too much as they are young, breast cancer is an adult on-set disease, and science will have improved a lot by the time they are at potential risk.

The other thing that has crossed my mind, when thinking about this in the past, is that if I did have the gene, would it make me reconsider becoming a mum. Maybe. I would have to really think about it. But I suspect I would go ahead as, as the counsellor pointed out, science will be a long way ahead by the time they are 'at risk'.

So, I am going to have blood taken as part of my routine appointment next Tuesday so I have a form to ask them to take more for the genetic testing at the same time. It takes 3-6 months for the testing to be completed (it is a little more complex than a routine test!) and when the results are in, I'll be invited back to discuss them. Keep everything crossed that me, mum and gran have just been 'unlucky' and that this thing doesn't having ongoing repercussions for the whole family...

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