I dealt with a very similar situation with my Dad. He has an esophagectomy with lymph node involvement and it was a very scary surgery! I don’t believe its the removal of the lymph notes that could cause the cancer to spread, but if they fail to remove all the cancerous cells from the lymph nodes.
Let your mom know that the surgery gives the best odds for long-term survival so she should be grateful that she is a candidate! there are a lot of people out there who hope and pray that they can have these types of surgeries but the cancer is too extended. Just reassure her that she is lucky, the odds of the arm swelling are small, and this is her best treatment option–the doctors wouldn’t steer her wrong 🙂
Hang in there!