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A marker of homologous recombination predicts pathologic complete response to neoadjuvant chemotherapy in primary breast cancer.


ABSTRACT: PURPOSE:To assess the prevalence of defective homologous recombination (HR)-based DNA repair in sporadic primary breast cancers, examine the clincopathologic features that correlate with defective HR and the relationship with neoadjuvant chemotherapy response. EXPERIMENTAL DESIGN:We examined a cohort of 68 patients with sporadic primary breast cancer who received neoadjuvant anthracylcine-based chemotherapy, with core biopsies taken 24 hours after the first cycle of chemotherapy. We assessed RAD51 focus formation, a marker of HR competence, by immunofluorescence in postchemotherapy biopsies along with geminin as a marker of proliferative cells. We assessed the RAD51 score as the proportion of proliferative cells with RAD51 foci. RESULTS:A low RAD51 score was present in 26% of cases (15/57, 95% CI: 15%-40%). Low RAD51 score correlated with high histologic grade (P = 0.031) and high baseline Ki67 (P = 0.005). Low RAD51 score was more frequent in triple-negative breast cancers than in ER- and/or HER2-positive breast cancer (67% vs. 19% respectively; P = 0.0036). Low RAD51 score was strongly predictive of pathologic complete response (pathCR) to chemotherapy, with 33% low RAD51 score cancers achieving pathCR compared with 3% of other cancers (P = 0.011). CONCLUSIONS:Our results suggest that defective HR, as indicated by low RAD51 score, may be one of the factors that underlie sensitivity to anthracycline-based chemotherapy. Defective HR is frequent in triple-negative breast cancer, but it is also present in a subset of other subtypes, identifying breast cancers that may benefit from therapies that target defective HR such as PARP inhibitors.

SUBMITTER: Graeser M 

PROVIDER: S-EPMC3432445 | biostudies-literature | 2010 Dec

REPOSITORIES: biostudies-literature

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A marker of homologous recombination predicts pathologic complete response to neoadjuvant chemotherapy in primary breast cancer.

Graeser Monika M   McCarthy Afshan A   Lord Christopher J CJ   Savage Kay K   Hills Margaret M   Salter Janine J   Orr Nicholas N   Parton Marina M   Smith Ian E IE   Reis-Filho Jorge S JS   Dowsett Mitch M   Ashworth Alan A   Turner Nicholas C NC  

Clinical cancer research : an official journal of the American Association for Cancer Research 20100827 24


<h4>Purpose</h4>To assess the prevalence of defective homologous recombination (HR)-based DNA repair in sporadic primary breast cancers, examine the clincopathologic features that correlate with defective HR and the relationship with neoadjuvant chemotherapy response.<h4>Experimental design</h4>We examined a cohort of 68 patients with sporadic primary breast cancer who received neoadjuvant anthracylcine-based chemotherapy, with core biopsies taken 24 hours after the first cycle of chemotherapy.  ...[more]

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