High-dose chemotherapy of breast cancer: is the question answered?

An on-site audit of the South African trial of high-dose chemotherapy for metastatic breast cancer and associated publications

PURPOSE

The randomized study reported by Bezwoda et al of high-dose chemotherapy (HDC) for treatment of metastatic breast cancer was audited on site to verify the study results. Additional published studies were reviewed to determine whether they had been subject to the required institutional oversight.

PATIENTS AND METHODS

Ninety patients were reported to have been randomized and treated on this trial. A log of the names, hospital numbers, entry dates, and regimen received had been provided by the principal investigator. A search of more than 15,000 sets of medical records available from two Johannesburg hospitals was performed to locate records for as many of these 90 patients as possible. Standard auditing techniques were used. Additional clinical trials published by Bezwoda were compared against the minutes of the University of the Witwatersrand Committee for Research on Human Subjects to verify review and approval.

RESULTS

Records for only 61 of the 90 patients could be found. Of these 61, only 27 had sufficient records to verify eligibility for the trial by the published criteria. Of these 27, 18 did not meet one or more eligibility criteria. Only 25 patients appeared to have received their assigned therapy temporally associated with their enrollment date, and all but three of these 25 received HDC. The treatment details of individual patients were at great variance from the published data. Nine other trials reported by Bezwoda were not reviewed or approved by the appropriate institutional committee despite statements to the contrary in the publications.

CONCLUSION

The multiple publications of this study do not report verifiable data, and nine other publications coauthored by the principal investigator contain at least one major untrue statement.

Bone marrow and lymph node assessment for minimal residual disease in patients with breast cancer

The immunocytological detection of disseminated epithelial cells in bone marrow in patients with breast cancer has been performed at many hospitals and institutes since the early 1980s. Despite numerous publications in this field, it has not been possible to standardize the method and establish the 'ideal' antibody, either nationally or internationally. Molecular biological methods using PCR technology could extend the diagnostic spectrum. However, one of the major problems in breast cancer is the lack of a disease-specific marker gene. As a result, immunocytology is still the standard procedure for tumour cell detection. The detection of disseminated single cells in bone marrow in primary breast cancer (also known as minimal residual disease) is a new prognostic factor for disease-free and overall survival. This has been demonstrated in two large (N > 300) groups and several small to medium groups (N = 50-300). As a marker of dissemination in a target organ for metastasis this prognostic factor corresponds much more closely to the tendency of breast cancer to early haematogenic spread. Tumour cell detection may predict the course of the disease better than the axillary lymph node status. Bone marrow aspiration and detection of disseminated cells might replace lymph node dissection, at least in those patients with small tumours and no clinical signs of lymph node involvement. This strategy will soon be investigated in appropriate studies. Another possible clinical use might be in deciding on whether or not to give adjuvant systemic therapy to node-negative patients. Patients with positive tumour cell detection are at a higher risk of subsequent metastasis, even if the axillary nodes are histologically normal. The immunohistological or molecular biological detection of tumour cells in axillary lymph nodes might also be very useful, now that it has been shown that a considerable subset of patients determined to be node-negative by means of conventional methods, are positive according to these new techniques. These methods could be a useful supplement to sentinel node biopsy. A further potential use of this method is in monitoring therapy with new treatment modalities such as gene therapy and immunotherapy. Repeated bone marrow aspiration can provide information on the success of therapy in minimal residual disease (cytoreduction). Immunocytochemical investigation of individual cells may be useful in studying the pathogenesis of metastasis, in particular in the skeleton. Phenotyping of cells might allow statements to be made on the metastatic potential of cells and the question of cell dormancy. It remains to be hoped that this aspect of minimal residual disease will be granted more attention in future.

Is there a role for intensive therapy in breast cancer?

With reference to survival, polychemotherapy has been demonstrated to be statistically significantly more effective than monochemotherapy both in the adjuvant setting and in the metastatic situation. Breast cancer demonstrates a dose-response relationship. Chemotherapy used in the conventional dose range should be given with adequate dose-intensity both in the adjuvant setting and for metastatic patients. More dose-intensive combinations are almost always associated with a higher response rate in patients' metastatic disease, but these results have seldom been translated into an improved survival. For marrow requiring high-dose therapy, repeated phase II studies have demonstrated the possibility of a survival tail, which may be due to stage migration and patient selection. At present we have at least 13 ongoing phase III studies in the adjuvant setting and at least 5 ongoing studies in the metastatic situation. These studies will give a definite answer on whether marrow-supported high-dose therapy is better than conventional therapy or if alternative approaches using tailored therapy will result in an equivalent outcome. In the future we must make better use of the present arsenal of drugs and examine the marked inter-individual variations in pharmacokinetic profiles for the drugs. We have to tailor the therapy to the tumour biological profile, in both the primary tumour and metastases with appreciation of heterogeneity and tumour progression. Based on these prerequisites, therapy can be either dose-intensive or in some instances continuous using lower doses.

Methodological arguments for the necessity of randomized trials in high-dose chemotherapy for breast cancer

In the past ten years high-dose chemotherapy with autologous haematopoietic stem-cell support (HD-CT) has increasingly been used for breast cancer. But the vast majority of trials are small phase I/II studies showing until now not enough evidence that HD-CT is superior to conventional-dose chemotherapy (CD-CT). In contrast to this, the public perception of this treatment is different. Patients as well as physicians often uncritically believe in reports contrasting the positive results obtained in case series treated by HD-CT with those of historical control groups. This leads to the problem that many patients and also clinicians are not willing to participate in randomized trials on this topic. A critical assessment of current knowledge on the effectiveness of HD-CT in breast cancer is given. The problems related to the use of historical controls, in general, and especially in the setting of HD-CT are demonstrated. Using data of patients treated with CD-CT within trials of the German Breast Cancer Study Group (GBSG) it will be shown that results similarly favorable to those reported from patients treated with a high-dose regimen may be produced using quite simple selection mechanisms. Comparisons of patients treated with HD-CT with historical control groups of patients treated with CD-CT may be misleading. A valid treatment comparison is only possible by means of large randomized trials. Clinicians should participate in the ongoing trials and enter all eligible patients.

Monotherapy of Metastatic Breast Cancer: A Review of Newer Agents

Purpose. New agents for the palliative treatment of metastatic breast cancer have emerged in the 1990s. This review summarizes the response rates of these agents with an emphasis on recent findings, such as presentations from the 1998 Meeting of the American Society of Clinical Oncology.

Methods. The English medical literature was reviewed to identify clinical trials involving monotherapy for the treatment of metastatic breast cancer. Three agents—paclitaxel, vinorelbine, and docetaxel—are emphasized because their databases are extensive enough to allow interesting comparisons. Liposomal-encapsulated anthracyclines, losoxantrone, gemcitabine, oral surrogates of continuous-infusion fluorouracil, raltitrexed, LY 231514, edatrexate, topoisomerase I inhibitors, and trastuzumab are reviewed briefly.

Results. Many of the new agents produce response rates approaching or even surpassing those achievable with doxorubicin monotherapy. Compared with older agents, some new agents have improved or at least different safety profiles, and some are easier to administer.

Discussion and conclusions. The new agents offer useful therapeutic options that make them suitable for combining with each other and with older agents, which could result in more effective regimens for metastatic disease, and, ultimately, primary disease in the adjuvant setting. The chemotherapeutic paradigms governing the management of breast cancer for the past three decades are likely to change as we move into the 21st century.

Dose-Intensified Chemotherapy for Breast Cancer: Present and Future Prospects

With the trend to maximize chemotherapy in breast cancer, the use of peripheral blood stem cells in addition to hematopoietic growth factors to alleviate myelosuppression caused by dose-intensified chemotherapy has been shown to be beneficial. In treatment of metastatic breast cancer, response rates and complete response rates as high as 100%and nearly 80%, respectively, have been reported. Such treatments have shown even greater promise in an adjuvant setting for high-risk breast cancer. High-dose chemotherapy studies, however, involve highly-selected patient populations who are generally compared with unselected patients, and controversy still surrounds the question of whether it is substantially superior to conventional-dose chemotherapy. There are now more than sufficient data to justify ongoing randomized trials, and the most important overall recommedation is to encourage patients to participate in these clinical trials.

Hematopoietic progenitor cell transplantation in breast cancer: current status and future directions

Breast cancer remains the second leading cause of cancer death despite numerous advances in medical science. In vitro, preclinical, and clinical trials have shown that chemotherapy dose intensity is an important component of therapy. Many clinical trials addressing the use of high-dose chemotherapy and hematopoietic cellular rescue have been conducted over the past decade. Early trials undertaken in heavily pretreated patients who had metastatic disease were associated with high treatment-related mortality rates; good response rates were noted but overall survivals were short. Subsequent technological advances, including the use of recombinant hematopoietic growth factors and peripheral blood progenitor cells as the source of cellular rescue, have dramatically lowered the morbidity and mortality of the procedure, as well as shortened hospital stay and markedly reduced cost. As a result, the high-dose chemotherapy approach has been used earlier in the disease course, both in patients with metastatic disease who were responding and in the adjuvant setting in patients at high risk for relapse. Results of many of these phase II trials are extremely encouraging, and phase III prospective, randomized trials comparing autotransplant to conventional approaches are currently under way. This review discusses past, current, and future initiatives of this modality. Included is a discussion of new preparative regimens, the addition of agents such as biochemical modifiers to enhance antitumor activity, and issues regarding timing of autotransplant, stem cell technology, use of allogeneic stem cells, and posttransplantation therapies.

Much ado about not...enough data: high-dose chemotherapy with autologous stem cell rescue for breast cancer

High-dose chemotherapy with autologous bone marrow or stem cell rescue (HDC/ASCR) has been proposed as a promising treatment strategy for breast cancer. Despite the frequency with which this procedure is performed, the role of HDC/ASCR in the treatment of breast cancer remains undefined. The purpose of this review is to examine the rationale for the procedure, the research progress to date, and the limitations of available data. A literature search of Medline from January 1966 through May 1997, CancerLit from January 1983 through May 1997, and Current Contents through May 1997 identified more than 600 English language papers or abstracts on this topic. Our review focuses on the preclinical and clinical data that explore the concept of chemotherapy dose intensity and the role of dose intensity in treating breast cancer. HDC/ASCR is based on the hypothesis that high-dose chemotherapy will overcome drug resistance, eradicate metastatic disease, and increase the proportion of women with breast cancer who are "cured." To date, results from only one phase 3 trial of HDC/ASCR compared with more conventional therapy have been published. Phase 2 and some phase 3 data on HDC/ASCR in the treatment of high-risk primary breast cancer and metastatic breast cancer are discussed. However, the results are inconclusive. The completion of national and international randomized trials is urgently needed to establish definitively the role of HDC/ASCR in the treatment of breast cancer.

Treatment choices by seriously ill patients: the Health Stock Risk Adjustment model

Anecdotal evidence suggests that patients who have life-threatening conditions often choose to undergo high-cost, high-risk treatments for them. This kind of risk-seeking behavior seems irrational because most patients are risk-averse. The Health Stock Risk Adjustment (HSRA) model seeks to explain this phenomenon. The model is based on the concept of relative health stock--the ratio of patients' expected quality-adjusted life years (QALYs) after a diagnosis to their expected QALYs before the diagnosis. The model predicts risk-averse patients will behave in a risk-seeking manner as their relative health stocks deteriorate. The HSRA model can help physicians better understand why some seriously ill patients seek high-risk treatments while others elect to forgo treatment. State legislatures and insurers are attempting to appropriately design insurance benefits for patients with life-threatening conditions. The HSRA model can help predict which patients will most likely take advantage of these benefits.

Complete remission of refractory gestational trophoblastic disease with brain metastases treated with multicycle ifosfamide, carboplatin, and etoposide (ICE) and stem cell rescue

Patients with chemotherapy-refractory gestational trophoblastic disease and brain metastasis are considered to have a very poor prognosis. We present the case of a patient who had failed several chemotherapeutic regimens. Despite transient responses to chemotherapy, she had not achieved a complete remission in 3 years, and had developed systemic disease and recurrent brain metastasis. She was treated with four cycles of high-dose ifosfamide, carboplatin, and etoposide with blood progenitor cell support. She tolerated this regimen well and has obtained a complete remission that is ongoing for 12 months.

Collection of circulating progenitor cells after epirubicin, paclitaxel and filgrastim in patients with metastatic breast cancer

The efficacy of high-dose chemotherapy (HDC) and circulating progenitor cell (CPC) transplantation in metastatic breast cancer (MBC) relies mainly on giving this treatment after a response to conventional induction chemotherapy has been achieved. For this reason an optimal mobilization regimen should be therapeutically effective while minimizing the number of leucaphereses required to support the myeloablative therapy. The combination of an anthracycline and paclitaxel in chemotherapy-untreated MBC has produced impressive response rates. We evaluated the CPC-mobilizing capacity of the combination epirubicin (90 mg m(-2)) and paclitaxel (135 mg m(-2)) followed by filgrastim (5 microg kg(-1) day(-1)) starting 48 h after chemotherapy administration in ten patients with MBC who were eligible for an HDC and CPC transplantation programme. Leucaphereses were performed by processing at least two blood volumes per procedure at recovery from neutrophil nadir when CD34+ cells in the peripheral blood exceeded 20 microl(-1). In most patients (six out of 10) more than 2.5 x 10(6) CD34+ cells kg(-1), a threshold considered to be sufficient for haematopoietic reconstitution, were collected with a single apheresis. In the remaining four patients an additional procedure, performed the following day, was enough to reach the required number of progenitors. These data suggest that the epirubicin-paclitaxel combination, besides being a very active regimen in MBC, is effective in releasing large amounts of progenitor cells into circulation.

The case for high-dose adjuvant chemotherapy in breast cancer: (II) clinical experience

Recent Phase II studies on the use of myelo-ablative chemotherapy in breast cancer have confirmed that this approach is associated with low mortality and apparent efficacy. In a preceding article the theoretical arguments were presented for testing this approach in the high-risk adjuvant setting; in the current article the clinical data justifying the present approaches for this type of treatment are reviewed. The evidence suggests that peripheral blood stem cell supported myelo-ablative chemotherapy should be tested against conventional regimens in order to determine whether or not the increased expense and toxicity of such an approach is associated with improved survival for women whose axillary node status places them at high risk of disease relapse and subsequent death.

Adenovirus-mediated gene transfer of herpes simplex virus thymidine kinase in an ascites model of human breast cancer

In this study, the growth of locally disseminated breast cancer was modeled using a human breast cancer cell line, MDA-MB-435A, adapted to grow as an ascites tumor in athymic mice. Ex vivo infection of MDA-MB-435A cells with adenovirus containing the herpes simplex virus thymidine kinase gene (HSV-tk) were injected into the intraperitoneal cavity of athymic mice. Ganciclovir (GCV) treatment resulted in prolonged median survival (117 vs. 34 days, p < 0.001) compared to untreated or control animals. Adenovirus containing HSV-tk also demonstrated therapeutic activity after in vivo transduction resulting in prolongation of median survival after GCV treatment (32 vs. 25 days, p < 0.001). However, compared to ex vivo treatment, the effect was modest. In an attempt to increase survival, the viral dose was increased three-fold. Instead of prolonging survival, the increased dose resulted in more toxic deaths. Necropsy demonstrated that the most significant histologic abnormality was marked, diffuse, cytomegalic changes in the liver. Polymerase chain reaction (PCR) analysis of hepatic DNA demonstrated the presence of the virus in the affected tissue. Similar host toxicity and hepatic abnormalities were seen in non-tumor-bearing mice treated with ADV/RSV-tk plus GCV. In conclusion, adenoviral vectors can successfully transfer genes in vivo to cancer cells growing as ascites tumors. Transduction with HSV-tk followed by GCV treatment can prolong survival in this model system of disseminated disease, however toxicity can be substantial. Further refinement in targeting expression of HSV-tk will be required to enhance the therapeutic benefit.

Autologous stem cell transplantation in breast cancer

High-dose chemotherapy with autologous stem cell support is an investigational treatment for patients with breast cancer who have a high risk of recurrence or who have metastatic disease. In the adjuvant setting, there is a lack of survival data from randomized studies comparing high-dose to conventional-dose therapy. High-dose adjuvant chemotherapy was found to result in as high as 71% 5-year event-free survival in patients with more than nine metastatic axillary lymph nodes in one nonrandomized study, which appears to be superior to those achieved with conventional-dose therapy. In metastatic breast cancer the great majority of patients die of cancer despite high-dose therapy with the current regimens, and it is unclear whether survival of these patients is improved with high-dose therapy as compared to conventional-dose therapy. However, a few patients with breast cancer with distant metastases have enjoyed a disease-free interval lasting for several years after high-dose therapy, which is rarely seen with conventional-dose therapy, and one small randomized trial showed improved survival in the high-dose arm of the study. The more extensive patient selection for high-dose chemotherapy needs to be taken into account when comparing the results achieved with different dose levels, and therefore a high priority should be given for randomized studies where high-dose therapy is compared with conventional-dose therapy.