Currently Preimplantation Genetic Diagnosis (PGD) for the breast cancer genes BRCA1/2 is viable and established, with positive results for those treated, state investigators.
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Following IVF, 717 embryos were found suitable for genetic analysis, and of these 43.1% were diagnosed as affected by the mutation, with 40.7% unaffected and thus suitable for transfer (the remainder had an abnormal genotype or the analysis was inconclusive). Hence, 62.1% of the PGD cycles led to fresh embryo transfer - with 3.6% transferred from one or two frozen-thawed unaffected embryos - resulting in 42 pregnancies in 40 women. Pregnancy rates were 41.4% per fresh embryo transfer and 23.1% per frozen. The overall pregnancy rate was 29%.
The series also included three cases of PGD on embryos previously cryopreserved for fertility preservation prior to chemotherapy, and these too resulted in two ongoing pregnancies.
Two female BRCA1 carriers were diagnosed with breast cancer within three months of the PGD treatment, despite breast screening shortly before treatment. One had a history of breast cancer, the other patient hadn't. The former patient went on to have healthy twins three years after the second breast surgery and chemotherapy, and following frozen/thawed embryo transfer.
So far, PGD for BRCA1 and BRCA2 gene mutations has been considered controversial. While most PGD procedures are indicated to remove completely the risk of inherited sex-linked and single-gene diseases (such as cystic fibrosis) in the children of affected couples, PGD for the breast cancer mutations cannot remove the risk completely - because the 10% background risk of breast cancer remains, even after PGD. Moreover, breast and ovarian cancers are usually of late onset, with prevention and therapeutic options constantly improving - so the chances of successful treatment, and many years of healthy life, are high.
Nor is breast cancer inevitable for a woman (or man) carrying a BRCA1/2 mutation. The controversy thus rests on the fact that a mutation in the BRCA genes increases susceptibility to breast or ovarian cancer, but does not reflect an inevitability for developing the diseases. However, with female carriers of a mutation in either gene having a lifetime risk of 60-80% for breast cancer, and a risk of 30-60% (BRCA1) or 5-20% (BRCA2) for ovarian cancer, many authorities have recognised the gravity of the risk and accepted a BRCA gene mutation as an indication for PGD.
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Professor Verpoest emphasised that the results, representing by far the biggest series of PGD for breast cancer in Europe, are robust, with a good unaffected pregnancy rate.
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"Our results suggest that PGD for BRCA1 and 2 mutations is feasible, with a good treatment outcome, but controversy will still remain over the ethical acceptability of PGD for a susceptible - yet preventable - condition."
Source-Eurekalert