Morbidity and mortality of ischaemic heart disease in high-risk breast-cancer patients after adjuvant postmastectomy systemic treatment with or without radiotherapy: analysis of DBCG 82b and 82c randomised trials. Radiotherapy Committee of the Danish Breast Cancer Cooperative Group

Adjuvant radiotherapy for breast cancer significantly improves overall survival: the missing link

BACKGROUND AND PURPOSE

The influence of surgical adjuvant radiotherapy on overall survival of patients with operable breast cancer is still a controversial subject. The negative result of the EBCTCG meta-analysis (Early breast cancer trialists', collaborative group. Effects of radiotherapy and surgery in early breast cancer. An overview of the randomised trials. N. Engl. J. Med. 1995;333:1444-1455) of clinical randomized trials on adjuvant radiotherapy in breast cancer is in strong contrast with the Danish 82B, 82C and British Columbia trials (Overgaard M, Hanse PS, Overgaar J, et al. Postoperative radiotherapy in high-risk premenopausal women with breast cancer who receive adjuvant chemotherapy. Danish Breast Cancer Cooperative Group 82b Trial. N. Engl. J. Med. 1997;337:949-955; Overgaard M, Jensen MB, Overgaard J, et al. Postoperative radiotherapy in high-risk postmenopausal breast-cancer patients given adjuvant tamoxifen: Danish Breast Cancer Cooperative Group DBCG 82c randomized trial. Lancet 1999;353:1641-1648; Ragaz J, Jackson S, Le N, et al. Adjuvant radiotherapy and chemotherapy in node-positive premenopausal women with breast cancer. N. Engl. J. Med. 1997;337:956-962) showing an impressive survival benefit. This paper tries to fill in the gap between the conflicting results.

MATERIALS AND METHODS

The 36 trials of the EBCTCG (Early breast cancer trialists', collaborative group, 1995) were prospectively screened for a number of objective parameters that are usually not analyzed in review papers. The odds of death data (and its variance) were borrowed from the original meta-analysis (Early breast cancer trialists', collaborative group, 1995) to check whether the objective features were significant predictors for overall survival benefit.

RESULTS

A significant survival benefit for the radiotherapy arm was found for recent trials (2P<0.05), large trials (2P<0.03), trials that used standard fractionation (2P<0.02), and trials with a favourable crude survival (2P<0.03). For these four parameters clear parameter-effect relations were found. In recent and large trials the odds reduction was 12.4% (2P=0.004).

CONCLUSIONS

Surgical adjuvant radiotherapy significantly improves overall survival of breast cancer patients provided that current techniques are used and treatment is given with standard fractionation. For the best subgroups we observed an odds of death reduction of more than 20%. The results of this study stress the importance of reducing cardiovascular and other late toxicity in adjuvant radiotherapy for breast cancer.

Myocardial perfusion imaging in breast cancer patients treated with or without post-mastectomy radiotherapy

PURPOSE

To assess the occurrence and location of myocardial perfusion defects in left-sided mastectomized breast cancer patients, treated with or without postoperative radiotherapy according to the guidelines from the Danish Breast Cancer Cooperative Group (DBCG).

PATIENTS AND METHODS

Seventeen left-sided breast cancer patients, with a median age of 59 years (range, 47-75 years), randomized to post-mastectomy irradiation plus systemic treatment, or systemic treatment alone, were examined after a median follow-up of 7.9 years (range, 6.0-12.2 years). The chest wall and the ipsilateral internal mammary nodes had been treated through two anterior-shaped electron fields, and the electron energy was chosen according to chest wall thickness, measured individually by ultrasound. The median absorbed dose was 50 Gy in 25 fractions, with 5 fractions/week. Information on clinical history was obtained and symptoms of ischemic heart disease (IHD), as well as major risk factors, were recorded. All patients had a physical examination, blood chemistry, electrocardiogram (ECG), chest X-ray and myocardial perfusion imaging by sestamibi-single photon emission computerized tomography (SPECT). SPECT-scanning was performed as a rest/dipyridamole 2-day protocol. The evaluation of regional myocardial perfusion was based on scintigrams using a 20-segment model.

RESULTS

There was no significant difference between the scintigraphic findings in the two groups. Four of ten irradiated patients and four of seven non-irradiated patients showed scintigraphic defects. An anterior defect was found in one non-irradiated patient.

CONCLUSIONS

This study does not indicate that the described radiotherapy technique induces detectable coronary artery disease. However, the small number of patients does not allow strong conclusions to be drawn.