Healing slowly in breast cancer side

See what your plastic surgeon says about this. If you had lymph node surgery at the same time as your mastectomy, that side had a lot more trauma. In my case, the lymph node was accessed through the breast incision, not through the armpit, but it still affected tissue throughout my whole torso, and the cancer side had more swelling, for many weeks. In some cases, there's an additional incision in the armpit to access/check/excise and biopsy the lymph nodes, and that side will definitely have longer healing as a result.

In my case, I had a hematoma on the right (cancer-affected) side, so because of that and the extra swelling, the drain was in longer on the cancer side, and the swelling took longer to go down. I also had slow healing, but probably not for the same reasons as yours. 15 years ago, I had a lumpectomy followed by radiation on that same breast, and the radiation scarring (although not outwardly visible) has made the blood supply worse, so the incision took 8 weeks to heal on the cancer side, and only 2.5 weeks on the non-cancer side.

I waited a long time before any saline fills. Didn't have any at all until it had been thoroughly healed for several weeks. didn't want to put extra pressure against a newly healed incision. This was my surgical oncologist's advice, although the PS was encouraging fills to start sooner.