Internal Mammary Node Irradiation Does Not Decrease Distant Metastases or Improve Survival in Stages I and II Breast Cancer

John Han-Chih Chang, MD
OncoLink Assistant Editor
Last Modified: November 1, 1999

Presenter: Barbara Fowble, MD
Affiliation: Fox Chase Cancer Center

Background:
Internal mammary node (IMN) irradiation has remained a controversial subject. Though historical data demonstrate that high-risk patients (axillary lymph node positive) have a significant rate of pathological IMN involvement, it continues to be debatable whether radiation treatment to IMNs along with definitive breast or chest wall RT improves outcome. The most recent randomized post-mastectomy trials have utilized IMN RT (in RT arms) with a positive impact on survival. However, which patient subsets truly benefits from the IMN RT remains unknown. In this study, the impact of IMN RT was studied.

Materials and Methods:

The authors reviewed over 1300 patients treated over a 15 year span from both the University of Pennsylvania and Fox Chase Cancer Center.
One hundred and fourteen patients had IMN RT (minimum of 46 Gy to a point 3 cm lateral to midsternum and 3 cm deep on the ipsilateral chest wall) via extended tangents.
The decision to treat the IMNs was made at the discretion of the treating physician, with most being treated because of positive axillary lymph nodes, inner or central lesions and T2 or greater lesions.
The two groups (patients receiving IMN RT versus no IMN RT) were fairly well matched for various patient and tumor characteristics; Patient numbers in the two groups were significantly different (114 versus 1269).

Results:

The evaluation of locoregional and distant relapse demonstrated NO difference in the outcome whether IMN RT was performed or not.
Survival was also NOT significantly improved with the addition of IMN RT.

Clinical/Scientific Implications:

This retrospective series has demonstrated that IMN RT seems to have NO significant effect on outcome.
Due to small numbers and patient selection biases that may enter into any retrospective data, it is difficult to establish that IMN RT has no utility in light of recent literature that incorporates IMN RT.
There are two ongoing European randomized trials (French and EORTC) addressing this issue (RT with tangents, regional lymph nodes +/- IMN RT). Those may be the only true confirmation of these data.
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