Internal mammary nodes in breast cancer

I would like to know if there is any specific way of finding out if the lymph nodes near the breastbone,also technically termed the internal mammary nodes are affected by cancer cells.My mother had a unitlateral mastectomy with lymph nodes removed from the axilla followed by chemo and radiotherapy to the chest wall and axilla.But the radiotherapist did not radiate the mediastinum and refused to explain to us why he chose to do so.If the nodes were'nt removed by surgery, is it possible to examine them by any non- invasive methods? What are the chances that it might be positive even after all these treatment modalities?

[Cleveland Clinic]

Dear whizmedico:  There is no non-invasive way to determine definitively if internal mammary nodes are involved with cancer. A CAT scan of the chest may or may not demonstrate enlarged internal mammary lymph nodes.  Randomized trials have shown that involved internal mammary nodes (IMN) have a similar prognostic value to axillary nodes, yet there was no survival benefit to extending mastectomy to include dissection of these nodes.  Further, radiation to the IMN’s have been associated with increased cardiotoxicity.  Therefore, even in cases where there is known IMN involvement, risk benefit ratios must be considered when contemplating therapy.

[whizmedico]

Thank you for clearing my doubts.

[darklily]

A related discussion, Internal mammary nodes was started.