Review of internal mammary chain irradiation in breast cancer

The aim was to assess the effectiveness of and indications for irradiation of the internal mammary chain (IMC) in the treatment of breast cancer based on a review of the literature. A computerized literature search was performed of the MEDLINE database from 1966 to March 1998. The data retrieved were ranked into levels of evidence as per convention. There was no Level I evidence found. Six randomized controlled trials and nine retrospective series were found pertaining to early stage breast cancer. Although some retrospective data suggested that IMC irradiation improved survival in mediocentral and axillary node-positive tumours, this was not supported by the randomized data. Two randomized trials were identified in high risk operable breast cancer. One of these showed a survival advantage to post-mastectomy irradiation, but the contribution of IMC irradiation to this could not be delineated. Based on the best current evidence, there is no advantage to elective IMC irradiation. The only indication is for positive IMC nodes where the management aim is palliative. The ongoing EORTC randomized trial may provide the definitive answer.