Sequential chemotherapy, surgery and radiotherapy in locally advanced breast cancer

Determining MDR1/P-glycoprotein expression in breast cancer

The mechanism of chemotherapy resistance in breast cancer is unresolved. MDR1/P-glycoprotein (P-Gp) over-expression confers multidrug resistance in vitro and might play a role in clinical breast cancer. Studies using clinical samples have yielded conflicting results. MDR1/P-Gp mRNA expression was determined relative to the expression in normal human liver using TaqMan real-time RT-PCR (corrected for expression of the housekeeping gene PBGD). Immunohistochemistry (IHC) was performed with monoclonal antibodies against P-Gp (JSB1, C219). The positive control was SW1573/2R160, the intermediate control SW1573 and the negative control GLC4/ADR. We assayed 9 breast-cancer cell lines by RT-PCR and IHC, 52 carcinoma samples by RT-PCR and 168 samples by IHC. SW1573/2R160 contained high levels of MDR1/P-Gp mRNA (1.0, equal to liver) and showed strong membranous staining. Expression of MDR1/P-Gp mRNA in SW1573 (0.05) and GLC4/ADR (3.2 x 10(-5)) was not detectable by IHC. Very low levels of MDR1/P-Gp mRNA were measured in breast-cancer cell lines (mean 3.1 x 10(-4), range 1 to 12 x 10(-4)), but P-Gp was not detected by IHC. In 25 specimens from chemotherapy-naive patients, MDR1/P-Gp mRNA levels varied from 1 to 11 x 10(-2) (mean 3.9 x 10(-2)). In sections of 80 chemotherapy-naive tumors, no membrane-bound staining was observed in the tumor cells. Tumors of 27 anthracycline-treated patients had comparable MDR1/P-Gp mRNA expression levels (mean 5.4 x 10(-2)). P-Gp was undetectable in 88 tumor samples of patients who had received anthracycline-based chemotherapy. In breast cancer, MDR1/P-Gp mRNA is low or absent and P-Gp levels in cancer cells are too low to detect by IHC. Chemotherapy exposure does not result in detectable MDR1/P-Gp over-expression.

Prophylactic supraclavicular fossa radiotherapy in early breast cancer: is it worthwhile?

A total of 291 consecutive patients with early breast cancer who did not receive any supraclavicular prophylactic irradiation of the ipsilateral fossa have been followed for a minimum of 5 years. Isolated relapse in that site occurred in 4.5% of patients and was controlled by radical radiotherapy with a post-relapse 5-year survival of 33%. Relapse with co-existing distant metastases occurred in a further 7% and no patient survived to 3 years. Supraclavicular fossa irradiation contributes to morbidity, does not improve survival and should be abandoned in favour of delayed treatment for proven recurrence.

Selection of therapy for stage III breast cancer

Locally advanced breast cancer is a heterogenous group including both operable and inoperable lesions. Local surgery or radiation alone produces poor survival rates, indicating micrometastases at diagnosis. Systemic chemotherapy as part of multimodality regimens has increased the length and rate of disease-free survival.