You're asking the right questions, Poliana. Traditionally, when a sentinel node is positive, surgery to remove all the underarm lymph nodes (20-40) is done. This is called an axillary node dissection and is done to reduce the chance of recurrence.

A trial called AMAROS published in 2013 found women diagnosed with early-stage breast cancer with a positive sentinel node are less likely to have lymphedema if they get radiation to their axillary lymph nodes instead of having them surgically removed. These results also showed axillary lymph node radiation reduces recurrence risk about the same amount as axillary lymph node surgery.
Read more here: https://www.breastcancer.org/research-news/outcome-same-for-early-bc-tx-w-node-rx-or-sx

Long-term results from another large clinical trial (https://pubmed.ncbi.nlm.nih.gov/28898379/) confirm that, for some women with early-stage breast cancer who have lumpectomy as their surgical treatment, a less extensive lymph node biopsy approach is sufficient.
Read more here: https://www.cancer.gov/news-events/cancer-currents-blog/2017/breast-cancer-lymph-node-removal

I recommend talking to your doctor about these various options and which is best for you.

My breast surgeon did not think it was necessary. You may have a unique circumstance about which I cannot comment. That said, I would, and did, seek a second opinion.

Is there a major cancer center near you?

Mayo Clinic, memorial Sloan Kettering, John’s Hopkins, Dana Farber etc. these kinds of hospital programs for breast cancer would be a good place to seek more information.

Hope this helps. 🌸