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PIK3CA-activating mutations and chemotherapy sensitivity in stage II-III breast cancer

Cornelia Liedtke1, Luca Cardone, Attila Tordai

  • 1Department of Breast Medical Oncology, University of Texas M, D, Anderson Cancer Center, Houston, TX, USA.

Breast Cancer Research : BCR
|March 29, 2008
PubMed
Abstract

Insights

PIK3CA mutations in breast cancer did not alter chemotherapy sensitivity. However, PIK3CA mutations were linked to fewer node-positive tumors, especially in ER-positive cases.

Area of Science:

  • Oncology
  • Genetics
  • Cancer Research

Background:

  • In vitro studies suggest PIK3CA activation influences chemotherapy sensitivity in cancer.
  • PIK3CA gene mutations are common in various cancers.

Purpose of the Study:

  • To investigate the association between PIK3CA mutations and chemotherapy response in breast cancer patients.
  • To determine if PIK3CA mutation status affects pathological complete response (pCR) or residual cancer burden (RCB) scores.

Main Methods:

  • Sequencing of tumor DNA from 140 stage II-III breast cancer patients for PIK3CA mutations (exons 1, 9, 20).
  • Correlation of mutation status with clinical/pathological parameters and chemotherapy response.
  • Stratification by estrogen receptor (ER) status, chemotherapy type, and specific exons.

Main Results:

  • 16.4% of patients had PIK3CA mutations, primarily in exons 9 and 20.
  • PIK3CA exon 9 mutations were more common in node-negative, particularly ER-positive, tumors.
  • No significant difference in pCR rates or RCB scores between wild-type and mutant PIK3CA groups.

Conclusions:

  • PIK3CA mutations are not associated with altered sensitivity to neoadjuvant anthracycline-based or taxane-based chemotherapy in breast cancer.
  • PIK3CA mutation was associated with a reduced rate of node-positive disease, especially in ER-positive breast tumors.

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