What's the deal with BRCA and Cancer?

Everybody has the BRCA1 gene, and the BRCA2 gene.  The genes are tumour suppressors, whose job is to find tumour/cancer cells and kill them or stop them growing, while other cells kill them.
However, in some people, there is a mutation in that gene, so that they don't do their job properly.  For example, statistically, it takes 6 mutations in a cell for it to become cancerous.  Ideally, when mutations happen within the DNA, the cell self-destructs, or if it gets past that stage, other cells notice and kill them.  So the chance of 6 mutations, that have sneaked past all the checkpoints, to happen in a single cell is fairly low.  However, in people with the BRCA1/2 mutations, there are fewer checkpoints, resulting in certain cancers being more likely.

BRCA stands for BReast CAncer, as that was the first cancer linked with that gene, but it is linked to other cancers too: ovarian, prostate, pancreatic, peritoneal cancer, amongst others. 
To complicate things slightly: not all breast cancers (for example) are a result of the gene - many more are just random cancerous mutations.  But, if you have the gene, you are much more likely to get those specific cancers.
In the normal population, a woman has a 12% lifetime risk of getting breast cancer, and less than 2% lifetime chance of getting ovarian cancer.  In myself, as a BRCA1 mutant, I have (had) a 40% chance of getting ovarian cancer, and have a whopping 85% chance of getting breast cancer.  For comparison, the NHS/BMA (I can't remember who, offhand) considers a "high chance of cancer" to be greater than 1 in 3, or 33%.

I found out I carried the BRCA1 mutation, because I underwent a genetic test, specifically looking for the mutation.  Because the mutation is hereditary, to qualify for the test you need to have either a strong family history of cancer, or have a relative known to have the gene mutation.  In my case, my mum is BRCA1. She was tested because back in 2015, she was diagnosed with Stage 4 Ovarian Cancer, coupled with the fact that her cousin had died of Ovarian Cancer, previously.

Another Stat: Most women diagnosed with ovarian cancer are diagnosed at stages 3 or 4.  Of those diagnosed at stage 4, only 15% survive for 5 years from diagnosis.

Thank God, my mum's cancer responds well to chemo, as it is now over 3.5yrs from diagnosis.  Her cancer has been recategorised as Chronic Cancer, meaning the risk will never fully go away as it is in her blood and in her lymphatic system, but as long as she is willing to go through chemo, she should continue to survive.  Her latest round of chemo started last week.  This is her third recurrence (so 4th time of having cancer), and the chemo treatment is due to last until next Jan/Feb depending on whether they stop over Christmas.

My mum has suffered with IBS and digestion issues for years, and frequently had ovarian cysts that needed to be removed and fibroids.  Every time she went to the doctor, she would be told it was her IBS.  And I do believe she had IBS.  However, Ovarian Cancer also has the same symptoms as IBS.  When she was finally diagnosed, it was Stage 4 meaning it had already spread, and was in the lymph nodes in her neck.  After 4 rounds of chemo, the tumour and shrunk enough in her abdomen to be removed by surgery, and was still 20cm x 10cm n size!  They also performed a full hysterectomy at the same time.

So, my mum was given the option of the genetic test, and was shown to be positive for the mutation in her BRCA1 gene.  As it is hereditary, I had a 50:50 chance of having inherited it, and both myself and my sister have.  Similarly, my children both have a 50:50 chance of having inherited it from me, but as it is not a childhood cancer, they can't be tested until they choose, over the age of 18yo.  Incidentally, my mum inherited the mutation from her father.  BRCA1 also increases the risk of breast cancer in men, and increases their risk of prostate cancer.

So, for me, the choice was obvious: full hysterectomy ASAP.  I have had my children, I never wanted more than two.  Though not totally silent, Ovarian Cancer is dubbed the Silent Cancer because it's symptoms often get mistaken for something else, and there is no reliable test for ovarian cancer.  So, I had my hysterectomy in 2016, and am now on HRT for the next 15-20 years because I am in Surgical Menopause.  I have no periods, no mood swings (at least that I'm aware of), and no menopausal symptoms like hot flushes or night sweats.
Most people with a BRCA mutation, only have BSO (Bilateral Salipingo Oopherectomy - only ovaries and fallopian tubes), rather than full hysterectomy, but I also suffered from heavy and painful periods so had everything removed. (I've just realised that at some point in the past two years, I've forgotten the medical terms for heavy and painful periods.  It's myrrh...something or other, I think. I just can't remember! Found it: Menorrhagia and Dysmenorrhea. Phew!)

My sister, otoh, opted to have a double mastectomy first of all.  She had reconstruction with expanders, and then implants.  I am planning to have PBM too (Prophylactic Bilateral Mastectomy) but in ~4 years time.  The reason for the delay is because I Home Ed my girls, and don't want to take time out from that, and for them having to miss their regular activities.  Additionally, the reconstruction I want to have is a DIEP flap - this basically, means that at the same time as having my breasts removed, I will have fat pouches taken from my stomach (you know I have plenty there!) to reconstruct my breasts from my own tissue.  This greatly reduces the risk of the new breasts being rejects, and puts my slow-grown tummy fat to good use!  But, being a much larger operation than having implants, it has a much longer recovery time.  Hence, why I'm waiting until my children are old and confident enough to use buses etc by themselves, to get themselves to dancing and groups.  That said, if DD2 follows in DD1's footsteps and decides to go to secondary school, then maybe I can get it done a year earlier than planned?  And it's why I'm using the 2B Mindset to help me lose weight, as I need to get my BMI below 30 in order to qualify for DIEP.

One more thought before I stop: I am soooooo thankful for the NHS in the UK.  It seems to get a bad rep, but is absolutely brilliant.  They have saved my mum, and are continuing to save her and return her to health.  They have saved me from ovarian cancer (though technically the risk is not 0%, it's pretty close).  The op I had done, was free at the point of use.  I do have to pay for my prescription of HRT patches but that is a small price to pay.  In comparison, for the op I had (Total Laparoscopic Hysterectomy with 1 night in hospital) would have cost me upwards of $25,000 in the US, so I may have considered not having this life saving treatment.