Long term follow-up of women treated with 16-week, dose-intensive adjuvant chemotherapy for high risk breast carcinoma

Combination of γ-radiation antagonizes the cytotoxic effects of vincristine and vinblastine on both mitotic arrest and apoptosis

PURPOSE

Combination therapy with different modalities is a common practice in the treatment of cancer. The promising clinical profile of vincristine and vinblastine has promoted considerable interest in combining these vinca alkaloids with radiation therapy to treat a variety of solid tumors. However, the therapeutic efficacy and the interaction between the vinca alkaloids with radiation is not entirely clear. In this study, we assessed the potential interactions in the combination of vincristine or vinblastine with gamma-radiation against human tumor cells in vitro.

METHODS AND MATERIALS

Vincristine or vinblastine and gamma-radiation were administrated at three different sequences designed as preradiated, coradiated, and postradiated combinations in human breast cancer cells and human epidermoid carcinoma cells. The cytotoxic interactions and mutual influences between these two modalities were analyzed by a series of assays including cytotoxic, morphologic, and biochemical examinations.

RESULTS

Our results showed that the combination of these two modalities did not produce any synergistic or additive effects. Instead, the clonogenic assays showed the survival rates of these combinations were increased up to 2.17-fold and 2.7-fold, respectively, of those treated with vincristine or vinblastine alone (p < 0.01). DNA fragmentation, TalphaT-mediated dUTP nick end labeling (TUNEL) assay, and flow cytometric assays also showed that the combination of gamma-radiation significantly interfered with the ability of these vinca alkaloids to induce apoptosis. Further analyses indicated that addition of gamma-radiation resulted in cell cycle arrest at the G(2) phase, which subsequently prevented the mitotic arrest induced by vincristine or vinblastine. In addition, biochemical examinations revealed that gamma-radiation regulated p34(cdc2)/cyclin B1 and survivin, and inhibited IkappaBalpha degradation and bcl-2 phosphorylation.

CONCLUSIONS

These results suggest that gamma-radiation might specifically block the cell cycle at the G(2) phase, which in turn interferes with the cytotoxic effects of vincristine or vinblastine on mitotic arrest and apoptosis. Thereby, it eventually results in an antagonistic interaction between these two modalities. This finding may be implicated in the clinical application of combination therapy of vinca alkaloids and radiation.

The CXCL12-CXCR4 chemotactic pathway as a target of adjuvant breast cancer therapies

Dose-dense adjuvant breast cancer chemotherapy is a new treatment strategy that aims to improve tumour control by using more frequent cytotoxic dosing together with continuous granulocyte colony-stimulating factor (G-CSF) to minimize neutropaenia. In addition to stimulating neutrophil proliferation, G-CSF mobilizes neutrophils from the bone marrow through proteolytic disruption of the chemokine receptor CXCR4 and its chemotactic ligand CXCL12. As breast cancers also express CXCR4 and oestrogen induces CXCL12, the success of dose-dense treatment could partly reflect inhibition of CXCR4-dependent micrometastatic homing and/or paracrine survival, and suggests a benefit of adjuvant oestrogen suppression for patients with oestrogen-receptor-negative, CXCR4-positive disease.

Long-term prognosis of breast cancer patients with 10 or more positive lymph nodes treated with CMF

The purpose of this investigation was to study the long-term prognosis of breast cancer patients with 10 or more positive lymph nodes after conventional chemotherapy treatment with cyclophosphamide, methotrexate and 5-fluorouracil (CMF). Between 1984 and 1989, 1048 node-positive patients were treated with CMF in two separate trials conducted by the German Breast Cancer Study Group (GBSG). Subgroups either received radiotherapy or tamoxifen in addition. In this study, long-term prognosis in the subgroup of 141 patients with 10 or more positive lymph nodes was investigated. Univariate and multivariate Cox models were used to evaluate the effect of prognostic factors on event-free survival (EFS) and overall survival (OS). Both univariate and multivariate analyses revealed the progesterone receptor (PR) status as the dominating prognostic factor for both EFS and OS, resulting in a strongly increased risk of more than 2-fold for receptor-negative patients. A large number of positive lymph nodes also affected the prognosis for EFS. In univariate analysis, the degree of lymph node involvement (i.e. percentage of positive nodes out of all examined nodes), oestrogen status (ER) status, and tumour grade also showed significant effects. To conclude, the prognosis in the subgroup of patients with 10 or more positive lymph nodes is heterogeneous. Some surprisingly high survival rates have been observed in case series of breast cancer patients treated with high-dose chemotherapy which may be explained by patient selection. From the usual factors investigated in this study, the PR status showed the strongest effect, and, at least this factor should be taken into account in the design and analysis of trials for breast cancer patients with a poor prognosis.