Noninvasive cardiac evaluation of patients receiving adriamycin-containing adjuvant chemotherapy (FAC) for stage II or III breast cancer

Noninvasive diagnosis of chemotherapy related cardiotoxicity

Chemotherapeutic agents reduce mortality and can prevent morbidity in a wide range of malignancies. These agents are, however, associated with toxicities of their own, and the treating physician must remain ever vigilant against the risk outgrowing the benefit of therapy. Thus, pre-treatment evaluation and monitoring for toxicity during and following administration is a fundamental tenet of oncologic practice. Among the most insidious and deadly toxicities of anti-tumor agents is cardiac toxicity, which in some cases may be irreversible. Early detection of cardiotoxicity allows the treating oncologist to redirect therapy or dose modify, taking into account the cost of a reduction in therapy against the potential of further injury to the patient. In these instances, the role of the cardiologist is to assist and advise the oncologist by providing diagnostic and prognostic information regarding developing cardiotoxicity. This review discusses noninvasive diagnostic options to identify and characterize cardiotoxicity and their use in prognosis and guiding therapy. We also review established protocols for cardiac safety monitoring in the treatment of malignancy.

Adjuvant systemic therapy for early breast cancer

Systemic therapy (chemotherapy or hormonal therapy) as an adjuvant to modalities of local control is now an integral part of the management of almost all patients with primary breast cancer metastatic to axillary lymph nodes. In addition, recent data suggest an expanding role for such treatments in patients without axillary involvement. Although some node-negative patients should probably not receive adjuvant therapy, the precise criteria to be used for selection are still under active discussion in the literature. Of the two types of systemic treatment, it is generally accepted that chemotherapy is indicated for premenopausal patients and that tamoxifen is useful for postmenopausal patients whose tumors contain estrogen or progesterone receptors. The recent analysis of several studies has suggested that chemotherapy may add to the benefits of tamoxifen in some postmenopausal patients as well. A possible role for tamoxifen in younger patients is being evaluated. For patients at relatively low risk of systemic relapse (i.e., those with zero to three involved axillary lymph nodes), no chemotherapy regimen has yet shown an advantage over 6 months of cyclophosphamide, methotrexate and 5-fluorouracil. For patients at high risk, however, doxorubicin-based regimens have demonstrated benefits. High-dose chemotherapies, some involving autologous bone marrow support, are being investigated for patients with ten or more involved nodes who are at very high risk of the eventual development of stage IV disease.

Adjuvant chemotherapy of breast cancer

Many women will not be cured of breast cancer by even the best early detection and surgical techniques because of micrometastases present at diagnosis. Adjuvant therapy has extended the disease-free interval for most patients and lengthens overall survival for many. Combination chemotherapy has become the standard form of adjuvant treatment for premenopausal women with breast cancer and positive lymph nodes after primary therapy. With minimal toxicity, disease-free and overall survival are improved. Results are less impressive or less clear-cut for postmenopausal women or any woman with negative lymph nodes. Long-term toxicities of adjuvant chemotherapy may include second malignancies and cardiac dysfunction. Although these complications probably are rare, they must be considered seriously when weighing chemotherapy for patients in whom its benefits may be slight. Innovations likely to become standard in adjuvant therapy decision making include risk assessment with new prognostic indicators (growth fraction, oncogene expression) and investigation of dose intensification using bone marrow growth factors and autologous stem-cell support.

Early and delayed clinical cardiotoxicity of doxorubicin

Five hundred thirty-four evaluable patients with breast cancer were treated with a combination of 5-fluorouracil, doxorubicin, and cyclophosphamide. The total planned dose of doxorubicin was 300 mg/m2 in patients with Stage II or III disease, and 450 mg/m2 in patients with isolated recurrences. The median time interval from start of adjuvant therapy to time of analysis was 68 months. Two percent had congestive heart failure associated with doxorubicin. Fifteen patients showed myocardial dysfunction attributed to either additional treatment with potentially cardiotoxic drugs for recurrent disease or other causes. The incidence of congestive heart failure was 1% in patients treated with up to 300 mg/m2, and 4% in patients who received 450 mg/m2 of doxorubicin. The median time interval from the end of doxorubicin to development of congestive heart failure was 1 month (range, 0-33 months). None of the 326 patients who have been followed 3 or more years (162 followed 5 or more years) since completion of doxorubicin therapy have developed congestive heart failure which was considered to be related from that therapy.