37/f. small lump at anal opening, skin colour. would this be a hemorrhoid or could it be anal cancer?

Need to examine: It is not feasible to provide a meaningful opinion without examining you. It could be hemorrhoid, tag from an anal fissure, a wart or some thing else. Anal cancer is unlikely at your age. You may watch and wait, if the "lump" more than doubles in size, ulcerates, bleeds, or develops a discharge, it would be prudent to see your doctor. Wish you good health!