medwireNews: BRCA mutation status does not impact survival in young women with breast cancer, results of a large prospective cohort study show.
However, the Prospective Outcomes in Sporadic versus Hereditary breast cancer (POSH) study also found that among women with triple-negative breast cancer, BRCA mutation carriers may have better overall survival (OS) during the first 2 years postdiagnosis than noncarriers.
Therefore ”[d]ecisions about timing of additional surgery aimed at reducing future second primary-cancer risks should take into account patient prognosis associated with the first malignancy and patient preferences,” Diana Eccles (University of Southampton, UK) and co-investigators remark.
The POSH study involved 2733 women aged 18–40 years recently diagnosed with a first invasive breast cancer at 127 UK hospitals. The majority of women (89%) received chemotherapy, typically anthracyclines with or without taxanes. Half of the women had a mastectomy and just under half (49%) had breast-conserving surgery, whereas the remainder did not have breast surgery.
During a median follow-up period of 8.2 years, 651 (24%) patients died of breast cancer and a further 27 (0.1%) died of other causes.
The researchers report in The Lancet Oncology that OS rates did not differ significantly between BRCA-positive (n=338) and BRCA-negative (n=2396) patients at 2 years (97.0 vs 96.6%), 5 years (83.8 vs 85.0%), or 10 years (73.4 vs 70.1%), even after adjustment for known prognostic factors such as ethnicity and BMI.
And similar results were observed for distant disease-free survival.
When the team focused on the 558 patients with triple-negative breast cancer, they found that BRCA mutation carriers (n=136) had significantly better OS than noncarriers at 2 years (95 vs 91%; hazard ratio=0.59) but not at 5 years (81 vs 74%) or 10 years (72 vs 69%).
Excluding the 31 patients who underwent bilateral mastectomy within the first year after diagnosis did not alter these findings.
This suggests “it is unlikely that the early bilateral mastectomy accounted for the early survival advantage in the BRCA mutation carriers with triple-negative breast cancer,” Eccles et al write.
Instead they speculate that the early survival advantage “might reflect greater sensitivity of BRCA-mutant breast cancers to chemotherapy or the greater visibility of BRCA-mutant cancers to host immune attack.”
They conclude that modern magnetic resonance imaging-based breast screening means “patients who choose to delay additional surgery for 1 or 2 years until they are psychologically and physically recovered from their cancer treatment can be reassured that this choice is unlikely to lead to any substantial survival disadvantage.”
Independent commentator Fiona MacNeill, from The Royal Marsden NHS Foundation Trust in London, UK, told reporters: “This study can reassure young women with breast cancer, particularly those with triple negative cancer or who are BRCA carriers that breast conservation with radiotherapy is a safe option in the first decade after diagnosis and double mastectomy is not essential or mandatory at initial treatment.
“In view of this, younger women with breast cancer can take time to discuss whether radical breast surgery is the right choice for them as part of a longer-term risk reducing strategy.”
By Laura Cowen
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