CREATE TABLE table_73859 ("Constituency" TEXT, "Candidate" TEXT, "Affiliation" TEXT, "Votes -cast" FLOAT, "Result - %" TEXT, "Loss/gain" TEXT)

What was the loss/gain when the votes -cast was 166?
SELECT "Loss/gain" FROM table_73859 WHERE "Votes -cast" = '166'
SELECT "Loss/gain" FROM "table_73859" WHERE "Votes -cast" = '166'