Aside from living in Florida, I don't know much about melanoma, and have zero medical training. I'm a pancreatic cancer patient who wound up in this thread by a random link. 🙂

With that said, in pancreatic cancer, the standard surgery (Whipple procedure) is very invasive and debilitating for several weeks/months; the average patient requires that much time for recovery before any adjuvant chemo or immunotherapy can start. They sometimes use neoadjuvant chemo to reduce tumor incursion into major arteries before surgery, and sometimes use it just to provide systemic therapy to prevent/kill potential metastases before surgery.

With melanoma on the arm, surgical removal doesn't seem like it should delay the immediate startup of immunotherapy. My inclination would be to undertake both immediately to prevent the spread and start the (potential) cure.

With pancreatic cancer (and many others; not sure about melanoma), the resected malignant tissue can be sequenced in various ways to identify mutations and also to create a tumor-specific ctDNA test like Signatera.

Signatera is a repeat blood test that counts the number of ctDNA cells matching your original tumor per mL of blood. It can be used as a metric to determine a treatment's effectiveness (e.g., it gives a quantitative result that you hope will go downward from non-zero to zero over the course of treatment).

It takes a couple weeks from tissue acquisition to create the Signatera test; the sooner they acquire and submit tissue the sooner they can start using it. It sounds like they already have tissue they could submit based on what they removed last year.

You would miss a few blood test opportunities if you started immunotherapy before the initial Signatera test is ready. The sooner you get it created, the sooner you can start using it. Again, I'm not sure if this is applicable for melanoma.

But the sooner you get surgery and immunotherapy, the sooner you start attacking the cancer from both sides. I would ask if there is any benefit to delaying the surgery vs. having surgery AND starting immunotherapy immediately.

Wishing you the best. Hope you can share your oncologist's responses regarding the above.