Stomach cancer. That depends on a lot of different things. Type of cancer, location, stage, etc. In general, stage 1 stomach cancer is treated by subtotal or total gastrectomy with lymphadenectomy. Having a sleeve gastrectomy is likely not an ideal option for you (unless it is a gist tumor on the greater curve of the stomach). You need to discuss with a surgical oncologist (not a bariatric surgeon) first.
Not really. If it is not invasive yet and it can be resected with the part of the stomach coming out then maybe. But if it is cancer, the. It is necessary to do a more extensive resection including lymph nodes.
Surgical resection. Why not just do the surgical gastrectomy ( partial/total- accordingly) - to remove the cancer for good. And in the same time with gastrectomy you will also loose your weight. Sleeve surgery can be done-but that does not address your stomach cancer. Very early stomach cancer can be cured with surgery.