P-glycoprotein: The intermediate end point of drug response to induction chemotherapy in locally advanced breast cancer

Hyun Cheol Chung, Sun Young Rha, Joo Hang Kim, Jae Kyung Roh, Jin Sik Min, Kyung Sik Lee, Byung Soo Kim, Kyi Beom Lee

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39 Citations (Scopus)


Expression and clinical relevance of p-glycoprotein (p-gp) were evaluated in 31 cases of locally advanced breast cancer and 9 cases involving inflammatory breast cancer after induction chemotherapy. The de novo p-gp expression rate was 26% and increased up to 58% (p = 0.03) with the FAC (5-fluorouracil, adriamycin, cyclophosphamide) regimen. Although more clinically complete responders were found in the secondary p-gp negative group (p = 0.02), this difference was not found in pathological tumor response. Moreover, as the grade of the secondary p-gp expression increased, the chemotherapeutic effect decreased, suggesting an inverse relationship between p-gp expression and drug effect (p = 0.04). When we subgrouped the patients into 4 groups using these two parameters, p-gp negative patients presenting with a high drug effect showed a low recurrence rate (p = 0.05) and marginal survival benefits (p = 0.09) as opposed to patients with a low drug effect. But in p-gp positive groups, the recurrence rate was the same between the two groups regardless of the drug effect. Thus, in the p-gp negative patient with a high drug effect, adjuvant chemotherapy with the same regimen as induction chemotherapy may induce more prognostically favorable results. Therefore, clinical application of the secondary p-gp detection can be used as an intermediate endpoint in evaluating drug response for an induction regimen.

Original languageEnglish
Pages (from-to)65-72
Number of pages8
JournalBreast Cancer Research and Treatment
Issue number1
Publication statusPublished - 1997

All Science Journal Classification (ASJC) codes

  • Oncology
  • Cancer Research


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