Adjuvant radiation trials for high-risk breast cancer patients: adequacy of lymphadenectomy

The recently published, widely publicized adjuvant radiation trials from Denmark and Canada concluded that the addition of postoperative radiotherapy (XRT) to modified radical mastectomy (MRM) and adjuvant chemotherapy reduces locoregional recurrences and prolongs survival in high-risk premenopausal patients with breast cancer. Our thesis is that adequate lymphadenectomies were not performed in either study. Consequently, the conclusion to these studies is not applicable to those patients who have undergone adequate surgery.

To better assess adequate lymph node yield from an MRM, a retrospective review was performed on 215 consecutive patients treated surgically for invasive breast cancer. Data from this review were compared with the surgical data from the above-mentioned radiotherapy trials.

In a group of 131 patients who had MRM, the average number of nodes removed was 26 (median, 25), and 75.5% of the specimens had 20 or more lymph nodes. In 73 patients who underwent segmental mastectomy with axillary lymph node dissection, both the average and the median number of lymph nodes removed were 24, and 68.9% had 20 or more nodes. These data compare to the Danish radiation trial in which a median of 7 lymph nodes were removed (with 76% of the patients having 9 or fewer lymph nodes in the specimen) and to the Canadian radiation trial in which a median of 11 lymph nodes were removed. In addition, in our breast cancer patients with positive nodes (84 of 204; 41.2%), 45.2.% (38 of 84) had more than three positive nodes compared with 29.8% in the Danish study and 35% in the Canadian study.

Our surgical data are sufficiently different from those of the Danish and Canadian studies to indicate that, in those studies, incomplete lymph node dissections were performed and that residual disease was left behind in the axilla in some or all of the patients. The addition of XRT in the setting of residual axillary disease may compensate for an inadequate operation and yield an acceptable oncological result; however, these studies did not provide an adequate comparison with a well-performed MRM without XRT. In the absence of documented benefit, XRT should not be routinely added if a complete lymph node dissection has been performed.