That is the conclusion of a team of researchers from the Institut Curie in Paris after studying a group of these high-risk patients for a median nine years after surgery for breast cancer. They found that these women, who were carrying either the BRCA1or BRCA 2 mutation, had no higher rate of recurrence than patients in the control arm of the study with no family history of the disease.
Dr Youlia Kirova told a news briefing at the 4th European Breast Cancer Conference that the only factor associated with a higher risk of recurrence was young age.
The study involved 131 patients (and 136 tumours) with a family history of breast and/or ovarian cancer who had been treated by breast conservation therapy and radiotherapy. They were matched with 261 patients with no family history. A fifth of the women with a family history of cancer carried BRCA mutations. Nineteen patients (involving 21 tumours) had a BRCA1 mutation and eight had a BRCA2 mutation.
Dr Kirova, an assistant professor in the radiotherapy department headed by Professor Alain Fourquet, said that the tumours in the BRCA carriers were more often grade III and oestrogen receptor negative. Grade III breast cancers are poorly differentiated and more aggressive and oestrogen negative tumours have a higher risk of spreading to other parts of the body and do not respond to hormone treatment.
"Despite the aggressiveness of these types of tumours we found after almost nine years of follow-up that there was no significant difference in recurrence between the BRCA carriers and the non-carriers with a family history or between the BRCA carriers and those with no family history."
However, added Dr Kirova, the rate of a new breast cancer appearing in the other breast was higher in all patients with a family history and for BRCA carriers it was increased between two and a half and three times.
"The only significant factor we found linked to a higher chance of recurrence was the age of the patient. With every year our patient becomes older the risk of recurrence decreases by 6%. This is a regular decreasing of the risk, but at the same time there are still a lot of uncertainties concerning BRCA mutations and age." Dr Kirova said that there was some evidence that BRCA tumours are more sensitive to radiotherapy and this may account for women with these aggressive tumours having no added risk of recurrence. This study, together with findings from another large study by other researchers, had confirmed this hypothesis. "The BRCA protein is involved normally in repairing damaged DNA. That includes repairing double strand breaks in DNA, which is the type of damage to cancer cells that radiotherapy induces. So, we believe that BRCA carriers are less able to overcome the damage that radiotherapy causes to the cancer cells."
While it was clearly encouraging to women with BRCA tumours that they were at no more at risk of recurrence than other patients, Dr Kirova stressed the importance of long-term follow up as there still remained a possibility of recurrence or new tumours in the same or opposite breast many years after diagnosis.
She concluded: "These findings are important, because every new study involving genetic testing helps us to understand more about breast cancer and increases opportunities for identifying and developing the optimum treatment for our patients."
Abstract no: 329 (16.00 hrs Thursday 18 March, Hall 6)
[1] Women who carry mutations in their BRCA 1 or BRCA 2 genes have a much higher than normal risk of developing breast cancer – between 50% and 80%. But these genes account for only 2.5% to 5% of breast cancers.
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