Systemic treatment for metastatic breast cancer is not curative, and the primary goal of therapy is maintenance and improvement in quality of life. In recent years, there has been a shift in medical oncology practice toward the use of less intensive chemotherapy in the metastatic setting, including the use of sequential single agents rather than combinations. The background of this trend is the lack of evidence that combination regimens improve survival. However, in December 2000, O’Shaughnessey et al. reported an improvement in the response rate and survival for women treated with the combination of capecitabine and docetaxel compared to docetaxel alone. A strong scientific rationale for this combination exists; namely, docetaxel upregulates thymidine phosphorylase, the enzyme that activates capecitabine to 5-fluorouracil. In addition to researchers looking at this combination in the adjuvant and neoadjuvant setting, physicians in practice are utilizing the regimen, particularly in women with rapidly progressing metastases.

RANDOMIZED TRIAL OF DOCETAXEL-CAPECITABINE VERSUS DOCETAXEL

There were several reasons to combine docetaxel with capecitabine. First, they are both very active agents in treating metastatic breast cancer. Second, they have largely non-overlapping toxicities, and thirdly and very importantly, the two agents exhibit a rare example of biochemical synergism. Docetaxel quite profoundly upregulates the expression of thymidine phosphorylase, the pivotal and last enzyme in the metabolism of capecitabine to 5-FU at the tumor site. Thymidine phosphorylase is overexpressed in a majority of human breast cancers as well as a number of other cancers. When you put docetaxel and capecitabine together, there is clear synergistic tumor cell killing. So this trial was attempting to see whether this could translate into anything of real importance in women with metastatic breast cancer.

—Joyce O’Shaughnessy, MD

In the docetaxel-capecitabine trial, concurrent use of docetaxel and capecitabine was better than single-agent docetaxel, and this surprised some people. The trial has been criticized, because not every patient who received docetaxel went on to receive second-line capecitabine. For the purist, trying to answer the question of sequential versus concurrent therapy, this trial doesn’t give us the exact answer. However, it is dramatic that there was a survival advantage in this trial. We have to take that very seriously.

—Edith A Perez, MD

Quality of life is a critical issue in treating advanced disease. If we prolong duration of response without a reasonable quality of life, we are kidding ourselves. The docetaxel-capecitabine study was one of the few clinical trials where quality of life was a major endpoint. A rigorous quality-of-life measurement was used before and during the study, showing that patients receiving combination docetaxel-capecitabine actually had a better quality of life than patients receiving full-dose docetaxel alone. Although this may seem paradoxical, my interpretation is that if a patient has a response — and for example, her fungating tumor is gone — she can get out of bed, walk around and go to work, then obviously, there’s a quality of life benefit.

—Daniel R Budman, MD

ENZYMATIC CONVERSION OF CAPECITABINE TO 5-FLUOROURACIL PHASE III TRIAL OF DOCETAXEL-CAPECITABINE (XT) COMBINATION THERAPY VS DOCETAXEL MONOTHERAPY (T) IN METASTATIC BREAST CANCER   X = capecitabine T = docetaxel EFFICACY OF XT VS T IN METASTATIC BREAST CANCER   Capecitabine/ Docetaxel Docetaxel Statistical Significance Time to progression 6.1 months [5.4-6.5] 4.2 months [3.4-4.5] log rank p=0.0001 CR + PR 42 [35.5-47.9]% 30 [24.2-35.7]% p = 0.006 Stable disease 38 [31.7-43.9]% 44 [38.0-50.5]%   Median survival 14.5 months [12.3-16.3] 11.5 months [9.8-12.7] log rank p=0.0126   Derived from Vukelja et al. 2001 San Antonio Breast Cancer Symposium. Abstract 352.   What first-line therapy would you recommend for the following patients with ER-negative, HER2-negative metastatic breast cancer? O N C O LO G I S T S DOCETAXEL DOCETAXEL/ CAPECITABINE PACLITAXEL VINORELBINE OTHER* NONE Asymptomatic 43-year-old woman with bone metastases who received adjuvant AC 35% 20% 10% 5% 25% 5% Asymptomatic 63-year-old woman with bone metastases who received adjuvant AC 35% 10% 20% 10% 15% 10% Asymptomatic 43-year-old woman with bone metastases who received adjuvant AC -T 15% 20% 5% 30% 20% 10% Asymptomatic 63-year-old woman with bone metastases who received adjuvant AC -T 30% - 5% 20% 30% 15% Very ill 43-year-old woman with liver and lung metastases who received adjuvant AC -T 5% 25% - 20% 50% - Very ill 63-year-old woman with liver and lung metastases who received adjuvant AC -T 20% 25% - 15% 40% - * The majority of therapies in this group included in “other” category were combinations of 2-4 chemotherapy agents, however, no combination accounted for more than 5% of those surveyed. Approximately what fraction of your patients with metastatic breast cancer receive combination chemotherapy at some point in their treatment of metastatic disease? O N C O LO G I S T S Mean 76% A 55-year-old woman with asymptomatic lung metastases has been started on capecitabine, 2000 mg/m 2 in two divided doses (2 weeks on, then one week off). After 3 cycles, she has had no changes in the lesions and no side effects. What would you generally do? O N C O LO G I S T S CONTINUE THERAPY 35% INCREASE DOSE TO 2500 MG/M 2 25% STOP CAPECITABINE/CHANGE THERAPY 20% CONTINUE CAPECITABINE/ADD OTHER AGENT 20%

Esteva FJ et al. Chemotherapy of metastatic breast cancer: What to expect in 2001 and beyond. Oncologist 2001;6:133-46. Abstract

Jassem J et al. Doxorubicin and paclitaxel versus fluorouracil, doxorubicin, and cyclophosphamide as first-line therapy for women with metastatic breast cancer: Final results of a randomized phase III multicenter trial. J Clin Oncol 2001;19:1707-15. Abstract

Nabholtz JM et al. Phase II study of docetaxel, doxorubicin, and cyclophosphamide as first-line chemotherapy for metastatic breast cancer. J Clin Oncol 2001;19:314-21. Abstract

Sledge GW Jr et al. Phase III trial of doxorubicin versus paclitaxel versus doxorubicin plus paclitaxel as first-line therapy for metastatic breast cancer: An Intergroup trial. Proc ASCO 1997; Abstract 2.

Twelves C et al. Adding Xeloda (capecitabine) to docetaxel significantly improves survival and does not compromise quality of life in patients with metastatic breast cancer. Breast Cancer Res Treat 2001; Abstract 542.

Vukelja SJ et al. Xeloda (capecitabine) plus docetaxel combination therapy in locally advanced/metastatic breast cancer: Latest results. Breast Cancer Res Treat 2001; Abstract 352.

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