Even *if* an "alkaline" body chemistry resulted in less of a chance of developing cancer, eating or drinking certain foods isn't the way you accomplish that goal. Food/drink does not change your body's pH. If you eat acidic foods, your body responds by producing less stomach acid. If you eat alkaline foods, your body responds by producing more stomach acid.
Your body controls its pH level primarily through the exhalation of carbon dioxide, as that affects the amount of carbonic acid in the blood.