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Expression of LRP and MDR1 in locally advanced breast cancer predicts axillary node invasion at the time of rescue mastectomy after induction chemotherapy.

Schneider J, Gonzalez-Roces S, Pollán M, Lucas R, Tejerina A, Martin M, Alba A - Breast Cancer Res. (2001)

Bottom Line: MDR1 mRNA expression detected by RT-PCR was associated with the presence of invaded axillary nodes at surgery in 18/22 cases (81.8%), compared with 13/24 (54.2%) in the group with undetectable MDR1 expression.This difference was statistically significant (P < 0.05).Persistence of previously detected MDR1-positivity after treatment (7/9 compared with 0/2 cases) was significantly associated with axillary node metastasis (P < 0.05).

View Article: PubMed Central - HTML - PubMed

Affiliation: Centro de Patologia de la Mama, Madrid, Spain. schneider@teleline.es

ABSTRACT

Background: Axillary node status after induction chemotherapy for locally advanced breast cancer has been shown on multivariate analysis to be an independent predictor of relapse. However, it has been postulated that responders to induction chemotherapy with a clinically negative axilla could be spared the burden of lymphadenectomy, because most of them will not show histological nodal invasion. P-glycoprotein expression in the rescue mastectomy specimen has finally been identified as a significant predictor of patient survival.

Materials and methods: We studied the expression of the genes encoding multidrug resistance associated protein (MDR1) and lung cancer associated resistance protein (LRP) in formalin-fixed, paraffin-embedded tumor samples from 52 patients treated for locally advanced breast cancer by means of induction chemotherapy followed by rescue mastectomy. P-glycoprotein expression was assessed by means of immunohistochemistry before treatment in 23 cases, and by means of reverse-transcriptase-mediated polymerase chain reaction (RT-PCR) after treatment in 46 (6 failed). LRP expression was detected by means of immunohistochemistry, with the LRP-56 monoclonal antibody, in 31 cases before treatment. Immunohistochemistry for detecting the expression of c-erb-B2, p53, Ki67, estrogen receptor and progesterone receptor are routinely performed in our laboratory in every case, and the results obtained were included in the study. All patients had received between two and six cycles of standard 5-fluorouracil, doxorubicin and cyclophosphamide (FAC) chemotherapy, with two exceptions [one patient received four cycles of a docetaxel-adriamycin combination, and the other four cycles of standard cyclophosphamide-methotrexate-5-fluorouracil (CMF) polychemotherapy]. Response was assessed in accordance with the Response Evaluation Criteria In Solid Tumors (RECIST). By these, 2 patients achieved a complete clinical response, 37 a partial response, and the remaining 13 showed stable disease. This makes a total clinical response rate of 75.0%. None achieved a complete pathological response.

Results: MDR1 mRNA expression detected by RT-PCR was associated with the presence of invaded axillary nodes at surgery in 18/22 cases (81.8%), compared with 13/24 (54.2%) in the group with undetectable MDR1 expression. This difference was statistically significant (P < 0.05). LRP expression in more than 20% of tumor cells before any treatment was associated with axillary nodal metastasis after chemotherapy and rescue mastectomy in 17/23 cases, compared with 3/8 in nonexpressors. Again, this difference was highly significant (P < 0.01). LRP expression before treatment and MDR1 mRNA expression after treatment were significantly interrelated (P < 0.001), which might reflect the presence of chemoresistant clones liable to metastasize to the regional nodes. Persistence of previously detected MDR1-positivity after treatment (7/9 compared with 0/2 cases) was significantly associated with axillary node metastasis (P < 0.05). Finally, in a logistic regression multivariate model, histology other than ductal, a Ki67 labeling index of at least 20% and the combination of LRP and MDR1 positivity emerged as independent predictors of axillary node invasion at the time of rescue mastectomy.

Conclusion: The expression of different genes involved in resistance to chemotherapy, both before and after treatment with neoadjuvant, is associated with the presence of axillary node invasion at rescue surgery in locally advanced breast cancer. This might reflect the presence of intrinsically resistant clones before any form of therapy, which persist after it, and could be helpful both for prognosis and for the choice of individual treatment.

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Strong reactivity with the LRP-56 monoclonal antibody of breast cancer tumor cells, as opposed to the inert stromal background. Streptavidin-biotin-peroxidase staining. Magnification ×400.
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Figure 2: Strong reactivity with the LRP-56 monoclonal antibody of breast cancer tumor cells, as opposed to the inert stromal background. Streptavidin-biotin-peroxidase staining. Magnification ×400.

Mentions: The pretherapeutic expression of LRP in more than 20% of tumor cells was significantly correlated with the subsequent presence of axillary nodal metastases (Spearman's test, r = 0.4725, P = 0.0084). In the preliminary univariate analysis giving rise to the final logistic regression model employed, LRP-positivity almost attained statistical significance for predicting nodal invasion (Table 2). Furthermore, the immunohistochemical reaction is easy to judge because the antibody can be employed at relatively low concentrations for a monoclonal (see the Materials and methods section), and thus gives virtually no background staining (Fig. 2), which makes the detection of reactive tumor cells very easy. No association of LRP expression and the subsequent response to therapy could be discerned (although this observation is of little value, given the low sample number and the fact that most tumors showed some response).


Expression of LRP and MDR1 in locally advanced breast cancer predicts axillary node invasion at the time of rescue mastectomy after induction chemotherapy.

Schneider J, Gonzalez-Roces S, Pollán M, Lucas R, Tejerina A, Martin M, Alba A - Breast Cancer Res. (2001)

Strong reactivity with the LRP-56 monoclonal antibody of breast cancer tumor cells, as opposed to the inert stromal background. Streptavidin-biotin-peroxidase staining. Magnification ×400.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC30705&req=5

Figure 2: Strong reactivity with the LRP-56 monoclonal antibody of breast cancer tumor cells, as opposed to the inert stromal background. Streptavidin-biotin-peroxidase staining. Magnification ×400.
Mentions: The pretherapeutic expression of LRP in more than 20% of tumor cells was significantly correlated with the subsequent presence of axillary nodal metastases (Spearman's test, r = 0.4725, P = 0.0084). In the preliminary univariate analysis giving rise to the final logistic regression model employed, LRP-positivity almost attained statistical significance for predicting nodal invasion (Table 2). Furthermore, the immunohistochemical reaction is easy to judge because the antibody can be employed at relatively low concentrations for a monoclonal (see the Materials and methods section), and thus gives virtually no background staining (Fig. 2), which makes the detection of reactive tumor cells very easy. No association of LRP expression and the subsequent response to therapy could be discerned (although this observation is of little value, given the low sample number and the fact that most tumors showed some response).

Bottom Line: MDR1 mRNA expression detected by RT-PCR was associated with the presence of invaded axillary nodes at surgery in 18/22 cases (81.8%), compared with 13/24 (54.2%) in the group with undetectable MDR1 expression.This difference was statistically significant (P < 0.05).Persistence of previously detected MDR1-positivity after treatment (7/9 compared with 0/2 cases) was significantly associated with axillary node metastasis (P < 0.05).

View Article: PubMed Central - HTML - PubMed

Affiliation: Centro de Patologia de la Mama, Madrid, Spain. schneider@teleline.es

ABSTRACT

Background: Axillary node status after induction chemotherapy for locally advanced breast cancer has been shown on multivariate analysis to be an independent predictor of relapse. However, it has been postulated that responders to induction chemotherapy with a clinically negative axilla could be spared the burden of lymphadenectomy, because most of them will not show histological nodal invasion. P-glycoprotein expression in the rescue mastectomy specimen has finally been identified as a significant predictor of patient survival.

Materials and methods: We studied the expression of the genes encoding multidrug resistance associated protein (MDR1) and lung cancer associated resistance protein (LRP) in formalin-fixed, paraffin-embedded tumor samples from 52 patients treated for locally advanced breast cancer by means of induction chemotherapy followed by rescue mastectomy. P-glycoprotein expression was assessed by means of immunohistochemistry before treatment in 23 cases, and by means of reverse-transcriptase-mediated polymerase chain reaction (RT-PCR) after treatment in 46 (6 failed). LRP expression was detected by means of immunohistochemistry, with the LRP-56 monoclonal antibody, in 31 cases before treatment. Immunohistochemistry for detecting the expression of c-erb-B2, p53, Ki67, estrogen receptor and progesterone receptor are routinely performed in our laboratory in every case, and the results obtained were included in the study. All patients had received between two and six cycles of standard 5-fluorouracil, doxorubicin and cyclophosphamide (FAC) chemotherapy, with two exceptions [one patient received four cycles of a docetaxel-adriamycin combination, and the other four cycles of standard cyclophosphamide-methotrexate-5-fluorouracil (CMF) polychemotherapy]. Response was assessed in accordance with the Response Evaluation Criteria In Solid Tumors (RECIST). By these, 2 patients achieved a complete clinical response, 37 a partial response, and the remaining 13 showed stable disease. This makes a total clinical response rate of 75.0%. None achieved a complete pathological response.

Results: MDR1 mRNA expression detected by RT-PCR was associated with the presence of invaded axillary nodes at surgery in 18/22 cases (81.8%), compared with 13/24 (54.2%) in the group with undetectable MDR1 expression. This difference was statistically significant (P < 0.05). LRP expression in more than 20% of tumor cells before any treatment was associated with axillary nodal metastasis after chemotherapy and rescue mastectomy in 17/23 cases, compared with 3/8 in nonexpressors. Again, this difference was highly significant (P < 0.01). LRP expression before treatment and MDR1 mRNA expression after treatment were significantly interrelated (P < 0.001), which might reflect the presence of chemoresistant clones liable to metastasize to the regional nodes. Persistence of previously detected MDR1-positivity after treatment (7/9 compared with 0/2 cases) was significantly associated with axillary node metastasis (P < 0.05). Finally, in a logistic regression multivariate model, histology other than ductal, a Ki67 labeling index of at least 20% and the combination of LRP and MDR1 positivity emerged as independent predictors of axillary node invasion at the time of rescue mastectomy.

Conclusion: The expression of different genes involved in resistance to chemotherapy, both before and after treatment with neoadjuvant, is associated with the presence of axillary node invasion at rescue surgery in locally advanced breast cancer. This might reflect the presence of intrinsically resistant clones before any form of therapy, which persist after it, and could be helpful both for prognosis and for the choice of individual treatment.

Show MeSH
Related in: MedlinePlus